^A .^■^''^ \ ',^^ >^ -o, ■'M V, ^ ,^^^^ ''^ '/. cy 'Vol; ^'^^^^^a^. \ The house or typhoid flj% Miinca domestica. Greatly enlarged. (Howard and Pierce, photo by Dovener.) 15 SANITARY ENTOMOLOGY THE ENTOMOLOGY OF DISEASE, HYGIENE AND SANITATION EDITED BY WILLIAM DWIGHT PIERCE, Ph.D. Consulting Entomologist, formerly Entomologist Southern Field Crop Insect Investigations Unittd States Department of Agriculture, Bureau of Entomology BOSTON RICHARD G. BADGER THE GORHAM PRESS Copyright, 19'21, by Richard G. Badger All Rights Reserved Made in the United States of America The Gorham Press, Boston, U. S. A. TO Dr. LELAND OSSIAN HOWARD Chief of the Bureau of Entomology, THIS book is DEDICATED to him, more than to any one else, do entomologists owe THE practical DEVELOPMENT OF THEIR SCIENCE, WHICH touches UPON EVERY HUMAN ACTIVITY. HE STOOD AMbNG THE FIRST TO EMPHASIZE THE IMPORTANCE OF SANITARY ENTOMOLOGY. HE STANDS NOW THE CHIEF EXPONENT OP ENTOMOLOGY THROUGHOUT THE WORLD. FOREWORD In May, 1918, a class was formed among the entomologists of the country to study the recent developments in the entomology of disease, hygiene, and sanitation, for the purpose of equipping themselves for any special service which they might be called upon to render during the war. The lectures were mimeographed week by week and mailed to the enrolled membership, which numbered in excess of 500. The war emergency is over and the mimeographed lectures have practically all been distributed. These lectures, however, dealt as much with domestic as with military problems, and they have now been com- pletely revised up to date of March 1, 1919, and are given forth as a series of lectures dealing with the entomological problems of peace times from the standpoint primarily of municipal, industrial, and household problems, and also with the hope that the course will be of assistance to teachers, and will stimulate research among investigators. Many important topics have been omitted, for we cannot hope to present the whole subject in a book of this size. This phase of entomology is one which is destined to become very important as our knowledge of disease transmission increases. There are many unworked and insufficiently worked problems now in sight, and these lectures will be found to suggest numerous possible lines of research. I wish at this time to express my appreciation of the services of Mr. Jacob Kotinsky, who served as Secretary of the Class, and of my collaborators in this course of lectui'es. As nearly as possible the International Rules of Nomenclature are followed, but in Entomology the practice had not been followed of en- closing the original author's name in parenthasis followed by the name of the author responsible for the present combination, and it has been impossible in the present volume to obtain all of the necessary information. W. DwiGHT Pierce. CONTENTS CHAPTER PAGE I. How Insects Can Carry ok Cause Disease 19 Classification of Methods by Which Insects Can Carry or Cause Disease 20 Why it is Necessary to Know How Insects Carry Disease ... 23 II. Some Necessary Steps in Any Attempt to Prove Insect Transmission or Causation of Disease 25 I. Cooperation 25 II. Where Should the Investigations of Insect Transmission Begin.^ 26 III. Fl.\n of Operation 26 IV. How Shall We Record Our Observations.^ 27 V. How C.\N an Insect be Involved in Disease Transmission.^ . 27 1. What Kind of Organisms Can Insects Carry.^ 27 2. In What Manner May Insect Toxins Bring About Disease.^ . . 27 3. Can Insects Themselves Cause Disease.^ 28 4. Where May Insects Obtain the Organisms Which Cause Disease? 28 5. How Can the Insect Transmit the Organism.* 28 6. What is the Course of the Organism in the Insect.* 29 7. What is the Course of the Organism on Leaving the Insect.* . . 29 VI. What is Known About the Disease to be Investigated.* . . 30 VII. Wh.\t Insects Should be Investigated.* 30 VIII. What is Necessary in the Transmission Experiments.* ... 31 IX. How Should Experimental Insects be Handled.* 32 III. A General Survey of the Needs of Entomological Sanit.\tion in America 34 The Insanitary Farm 35 How TO Improve Farm Sanitation 36 The Insanitary Town 38 How to Improve Sanitation 38 Sanitary Problems of Cities 39 Entomological Requirements of Municipal Sanitation 40 Industrial Sanitation 41 IV. A General Survey of the Seriousness of Insect Borne Diseases to Armies 43 V. Relation of Insects to the Parasitic Worms of Vertebrates ... 50 Mode of Infection of Insect Hosts 51 Mode of Infection of Vertebrate Hosts 52 Species of Worms Found in Insects 52 Cestoda or Tapeworms 53 Dipylidium caninum (Linnaeus, 1758) Railliet, 1892 53 Hymenolepis diminitta (Rudolphi, 1819) Bhmcliard, 1891 .... 54 Hymcnolcpis nana (Siebold, 1852) Blanchard, 1891 55 ('hoaiiotapiiia iiifundibulum (Bloch, 1779) Cohn, 1899 56 Otlier Tapeworms 57 Trematoda or Flukes 57 CONTENTS pagf; NeMATODA or RorXDWORMS 58 1. Parasitic Nematodes Whose Eggs or Larvae Leave the Body of the Final Host in the Feces 60 Protospinira mnris (Gmelin, 179{>) Seurat, 1915 60 Spirocerca mnguinolcnta (Rudolpiii, 1819) Railliet & Henry, 1911 . 60 .S/;/r«mf/f/.v/ro/)/n7« (Mueller, 1894) Marotel, 1912 61 Gougijliiiirma sriitatum (Mueller, 18(59) Railliet, 1892 62 GoiKjijlourma miisrronatiim Seurat, 1916 63 Goiif/yloncma brcrispiniliim Seurat, 1914 63 Gougi/loncma ncoplasficiim (Fibiger and Ditlevsen, 1914) Ransom and Hall, 1916 63 /lrf/HP/(«« .s7rortyi//(«a (Rudolphi, 1819) Railliet and Henry, 1911 . . 64 Phy.soccphalus sexahdns (Molin, 1860) Diesing, 1861 ."..... 64 Habronema muscae (Carter, 1861) Diesing, 1861 65 Habrnncma microstoma (Schneider, 1866) Ransom, 1911 67 Habronema mcgasiotna (Rudolphi, 1819) Seurat, 1914 67 Acuaria spiralis (Molin, 1858) Railliet, Henry and Sisoff, 1912 . . 67 Filaria gallinanim Theiler, 1919 68 Ascaris lumbricoides Linnaeus, 1758 68 2. Parasitic Nematodes Whose First-Stage Larvae Occur in the Blood or Lymph of the Final Host and Leave the Body Through Ingestion by Blood-Sucking Insects 69 Filaria bancrofti Cobbold, 1877 69 Filaria (Loa) loa (Cobbold, 1864) 71 Filaria dcmurqitayi Manson, 1895 71 Filaria philippinensis Ashburn and Craig, 1906 72 Filaria himimana Biglieri and Araoz, 1917 72 Filaria cypseli Annett, Button and Elliott, 1901 72 Filaria martis Gmelin, 1790 73 Z)?rq^/ar?« z/nmiVjs (Leidy, 1856) Railliet and Henry, 1911 .... 73 D/rq/i/ar/fl rf^jens, Railliet and Henry, 1911 74 Acanlhorhcilonema perstans (Manson, 1891) Railliet, Henry and Lan- gcron, 1912 74 Acantliocheilonema grassii (Noe, 1907) Railliet, Henry and Langeron, 1912 . 75 Acantliocheilonema reconditum (Grassi, 1890) Railliet, Henry and Lan- geron, 1912 \ . . . 76 Setaria labiate- papillosa (Alessandrini, 1838) Railliet and Henry, 1911 77 Oncocerca 77 3. Other Nematodes 77 4. Mermithidae 78 GoRDiACEA OR Horse-Hair Worms 78 ACANTHOCEPHALA OR ThORN-HeADED WoRMS 79 Macracanthorhynchus hirudinaceus (Pallas, 1781) Travassos, 1916 ... 79 Mon!7iJor??u'.y 7?io/n7/for/?n> (Bremser, 1819) Travassos, 1915 79 Compendium of Parasites Arranged According to Insect Hosts . . 79 Aphaniptera (Siphonaptera) — fleas 79 Diptera — flies 80 Neuroptera 82 Trichoptera — hairy-winged insects 83 Lepidoptera — moths, butterflies 83 Coleoptera — beetles 84 Mallophaga — bird lice 86 Isoptera — termites 87 Odonata — dragonflics 87 Plectoptera — nia.^flies 87 Plecoptera — stoneflies 88 Orthoptera — cockroaches, etc 88 Dermaptera — earwigs 88 Myriapoda — millipedes, centipedes 88 Acarina — ticks, mites 88 Isopoda — sowbugs 89 List of References . 89 CONTENTS xi H AFTER PAGE VI. The Relations of Climate and Life and Their Bearings on the Study OF Medical Entomology 97 VII. Diseases Borne by Non-Biting Flies 105 Plant Organisms Carried by Non-Bitixg Fliks 107 Thallophyta: Fungi: Schizomycetes: Coctacese 107 Thallophyta: Fungi: Schizomycetes: Bacteriacese 109 Thallophyta: Fungi: Schizomycetes: Spirillaccse 115 Summary of Plant Organisms 115 Diseases of Unsettled Origin Probably Caused by Microorganisms 116 Animal Organisms Carried by Non-Biting Flies 116 Protozoa 116 Sarcodina: Amoebina: Amoebidse 110 Mastigophora: Protomonadina: Bodonidie 117 Mastigophora : Polymastigina: Polymastigidse 117 Mastigophora: Binucleata: Leptomonidse 117 Mastigophora: Binucleata: Trypanosomidse 119 Mastigophora: Spirochsetacea : Spirochaetidse 119 Neosporidia: Myxosporidia: Nosemidse 120 Protozoa: Neosporidia: Myxosporidia: Thelohanidae 120 Higher Organisms Carried by Flies 120 Platyhehiiia : Cestoidea: Cyclophyllidea: Tseniidse 120 Platyhelmia: Cestoidea: Cyclophyllidea: Hymenolepididae 120 Platyhelmia: Trematcda: Malacotylea: Schistosomidse 120 Nemathelminthes: Nematoda: Spiruridae 121 Nemathelminthes: Nematoda: Ascaridse 121 Nemathelminthes: Nematoda: Oxyuridae ■ 121 Nemathelminthes: Nematoda: Ancylostomidse 122 Nemathelminthes: Nematoda: Trichosomidae 122 Important General Text Books 123 Special References 123 VIII. Important Phases in the Life History of the Non-Biting Flies . , 126 House Fly, Musca Domestica Linn^us 127 The Blue Bottle Flies of the Genus Calliphora 130 The Sheep Maggots or Green Bottle Flies 131 Other Screw Worms and Blow Flies 132 Other Excrement Breeders 135 References 137 IX. Common Flies and How to Tell Them Apart 138 Table to Separate the Adult Flies 139 The Larvae; or Maggots 141 Descriptions of Larvae or Maggots 141 Table to Separate the Larvae (Maggots) 142 Fannia canicidariftYAunaixis, and Fannia scalaris VaXivicms 144 Musca domestica Linnaeus I44 Stomoxys calcitrans Linnaeus , I45 Muscina stabulans Fallen 146 Calliphora erythroccphala Meigen I47 Calliphora vomitoria Linnaeus 148 Lucilia sericafa Meigen 148 Chrysomya macellaria Fabricius I49 SarcophagidcB 150 Bibliography 151 X. The Control of the House Fly and Related Flies 153 Repressive Measures I53 Striking the Source I53 Manure 153 xii CONTENTS CHAPTEK pjlQjj Garbage 160 Excreta 161 Carcasses 161 Miscellaneous Breeding Places 162 Palliative Measures 162 XI. Control of Flies in Barn Yards, Pig Pens and Chicken Yards . . . 167 Repression of Flies in Barn Yard 167 Fly Control in Pig Lots and Pens 170 Prevention of Fly Breeding in Chicken Houses and Yards . . . 173 XII. Myiasis — Types of Injury and Life History, and Habits of Species Concerned 175 Tissue-Destroying Forms 176 Subdermal Migratory Species 182 Intestinal and Urogenital Myiasis 190 Forms Producing Myiasis in Head Passages 193 Bloodsucking Forms 195 Some Bibliographical References 196 XIII. Myiasis — Its Prevention and Treatment 200 Tissue-Destroying Forms 200 Subdermal Migratory Species 204 Species Causing Intestinal and Urogenital Myiasis 205 Species Infesting Head Passages 207 Bloodsucking Species 208 XIV. Diseases Transmitted by Bloodsucking Flies 209 Plant Organisms Carried by Bloodsucking Flies 209 Thallophyta: Fungi: Schizomycetes : Bacteriacese 209 Thallophyta: Fungi: Schizomycetes: Coccacese 210 Diseases of Unknown or Uncertain Origin 211 Animal Organisms Transmitted by Bloodsucking Flies 212 Protozoa 212 Mastigophora : Binucleata: Hsemoproteidse 212 Mastigophora : Binucleata: Leucocytozoidae 214 Mastigophora: Binucleata: Trypanosomidse 214 Mastigophora: Binucleata: Leptomonidae 219 Masti^'oifiiora: Spirochsetacea : Spirochsetidse 216 Telosporidia: Usemogregarinida : Haeniogregarinidae 219 Metazoa 220 Nemathelniinthes: Nematoda: Filariida? 220 Bibliography 220 XV. Biological Notes on the Bloodsucking Flies 223 Family Chironomid^ 223 Midges 223 Family Simuliid^ 224 Buffalo Gnats 224 Family Psychodid^ 226 Pappataci Flies 226 Family Culicid^ 228 Family Tabanid.e 228 Horse Flies 228 Family Muscid^ 228 Bloodsucking Fly Larvae 228 Biting Species of Musca 229 True Biting Flies 229 Stable Flies 230 CONTENTS xiii CHAPTER PAGE Horn Flies 232 Tsetse Flies 234! pupipara 235 References 235 XVI. Biology and Habits of Horse Flies 236 Eggs and Egg Laying 237 Larv^ 240 Pup^ 243 Life Cycle ' 243 Habits of Adults 244 Concerning Control Measures 245 Bibliography 246 XVII. Diseases Transmitted by Mosquitoes 247 Diseases of Uncertain Origin Transmitted by Mosquitoes .... 248 Plant Organisms Transmitted by Mosquitoes 249 Thallophyta: Fungi 249 Thallophyta: Fungi: Schizomycetes : Bacteriacea- 249 Animal Organisms Transmitted by Mosquitoes 249 Protozoa 249 Mastigophora: Binucleata: Haemoproteidae 249 Mastigophora : Binucleata: Leucocytozoida; 250 Mastigophora: Binucleata: Trypanosomidae 250 Mastigophora: Binucleata: Leptomonidse 251 Mastigophora: Binucleata: Plasmodidae 252 Mastigophora: Spirochsetacea : Spirochfetidae 259 Mctazoa 260 Platyhelmia: Fasciolidis 260 Nemathelminthes: Nematoda: P^ilariidae 261 Nemathelminthes: Nematoda: Mermithidje 262 References ' 263 XVIII. Wh.\t V\'e Should Know About Mosquito Biology 266 OviPOSITION AND THE EgG StAGE 267 The Larv.e and Their Habits 268 The Pup^ 272 Adult Mosquitoes 272 Table of American Disease-Carrying Mosquit.)es 273 References 274 XIX. Mosquito Control 275 Prevention of Mosquito Breeding 275 Scouting 275 Determination of Source of Mosquitoes 276 Leveling and Filling Water Holes 276 Ditching and Clearing Streams and Swamps 276 Clearing of Weed-Filled Bays and Lakes 277 Drainage 277 Larvicides 279 Oiling 280 Artificial Containers of Mosquito Larva- 282 Fish as Mostjuit') Control 282 Destruction of Adult Mosquitoes 283 Protection from Mosquitoes 283 Protection of Dwellings from Mosquitoes 283 Protection of the Individual 283 Bibliography 285 xiv CONTENTS CHAPTER PAOS XX. Louse Borne Diseases 286 I. Direct Effect of Lovse Attack 286 1. Types of Pediculosis Corporis 286 2. Types of Pediculosis Capitis 287 3. Types of Phthiriasis 287 4. Effects of Attack of Other Lice 288 IL Transmission of Diseases by Lice 289 1. Diseases of Plant Origin 289 Thallophyta: Fungi: Ascomycetes: Gymnoasceae 289 Thallophyta: Fungi: Hyphomycetes 289 Thallophyta: Fungi: Schizomycetes: Coccace£e 289 Thallophyta: Fungi: Schizomycetes: Bacteriacese .... 290 Summary of Plant-Caused Diseases 290 2. Diseases of Unknown or Uncertain Origin 291 3. Diseases of Animal Origin 294 Protozoa 294 Mastigophora : Binucleata: Trypanosomidse 294 Mastigophora: Binucleata: Leptomonidse 294 Mastigophora: Spirochaetacea: Spirochaetidse 295 Telosporidia: Haemogregarinida : Haemogregarinidae . . . 296 Metazoa 297 Platyhelniia: Cestoda: Cyclophyllidea: Tseniidse .... 297 Bibliography 297 XXI. The Life History of Human Lice 301 References .311 XXn. The Control of Human Lice 312 The RXvages of Lice 312 Reservoirs of Louse Breeding 313 Control Measures 314 Control of Lice on the Body 316 Control of Crab Louse 310 Control of Head Louse 316 Control of Body Louse 317 Control of Lice in Clothing 319 1. Laundry 319 2. Dry Cleaning 320 3. Steam Sterilization 321 4. Hot Air Delousing 324 5. Fumigation 324 6. Storage 326 7. Impromptu Deloucing Arrangements 326 Control OF Lice in Living Quarters 327 Control of Lice in Hospitals 328 Control of Lice in Hospitals 328 Louse-Proof Garments for Medical Attendants, etc 328 Bibliography 328 XXIII. Lice Which Affect Domestic Animals 330 Part 1. Cattle Lice and Their Control 330 Sucking Lice 331 Biting Lice 332 Methods of Study of Life History 333 Control Measures 334 Oils 334 Sprays 335 Miscellaneous Remedies 337 Time for the Application of Control Measures 338 Skin Injuiies 338 CONTENTS XV CHAPTER PAGE Part 2. Lice Affecting Chickens, Hogs, Goats, Sheep, Horses, and Other Animals 33!) Lice Infesting Domestic Fowls 339 Lice Infesting Rabbits, Cats and Dogs 343 The Hog Louse SU Lice Attacking Sheep 3-lo Biting and Sucking Lice of Cioats 34(5 Lice of the Horse . 347 Important Bibliographical References 348 XXIV. Diseases Carried by Fleas 350 Plant Organisms Transmitted by Fleas 350 Thallophyta: Fungi: Schizomycetes: Bacteriacese 350 Animal Organisms Transmitted by Fleas 35*2 Protozoa 35''2 Mastigophora : Binucleata: Trypanosomids 352 Mastigophora : Binucleata: Leptomonidse 354 Mastigophora: Spirochfetacea: Spirochsetidae 355 Telosporidia: Grcgarinida: Agrippinidse 355 Telosporidia: Haemogregarinida: Hsemogregarinidse 355 Metazoa 355 Platyhelmia: Cestoidea: Cyclophillidea: Tseniidse 355 Platyhelmia: Cestoidea: Cyclophillidea: Hymenolepididse .... .356 Nemathelminthes: Nematoda: Spiruridse 357 Nemathelminthes: Nematoda: Filariidse 357 Summary 357 References 358 XXV. The Life History and Control of Fleas 360 Factors Influencing Abundance of Fleas 366 Control of Fleas 367 List of References 371 Notes on the Chigoe, Dermatophilus Penetrans 373 XXVI. Cockroaches 374 Biology 375 Key to the Four Principal Household Cockroaches 376 Blafta orientalis (Linnaeus) 376 BlaUella germanica (Linnaeus), Caudell 377 Periplaneta americana (Linnaeus) 378 Periplaneta australasia (Fabricius) Burmeister 380 Remedies 380 Fumigation . 380 Hydrocyanic Acid Gas 380 Carbon Bisulphide 380 Pyretlorum Powder 381 Sulphur 381 Poisons 381 Sodium Fluoride 381 Bora.K . 381 Pyrethrum Powder 382 Phosphorus 382 Sulphur 382 Castor Oil 382 Traps . . . . ■ 382 Enb:mies 382 XXVII. Diseases Transmitted by the Cockroach 383 Plant Organisms 383 Thallophyta: Fungi: Coccaceae 383 Thallophyta: Fungi: Bacteriaceae 384 Thallophyta: Fungi: Spirallaceae ' .387 xvi CONTEXTS CBAPTEH PAOB Animal Organisms 388 Protozoa 388 Sarcodina: Amoebina: Amoebiciae 388 Mastigophora: Polymastigina : Tetramitidae 388 IMastigophora: Binucleata: Leptonionidse 388 Telosporidia: Grogarinida: Gregarinidse 388 Telosporidia : Cocoidiidea: Eimeriid£E 388 Neosporidia: Myxosporidia: Thelohaniidse 388 Ciliata: Heterotrioha: Bursarinidse 388 Metazoa 389 Platyhelmia: Cestoidea: Hj'menolepididse 389 Nemathelminthes: Acanthocephala : Gigantorhyncliida? 389 Nemathelminthes: Xematoda: Spiniridse 389 Nemathelminthes: Xematoda: Oxyuridaj 389 References 399 XXVIII. The Bedbug and Other Bloodsucking Bugs: Diseases Transmitted, Biology and Control 391 Diseases of the Plant Kingdom Transmitted by Bugs 392 Thallophyta: Fungi: Bacteriaceae 392 Diseases of Uxknown Origin 393 Diseases of the Animal Kingdom Transmitted by Bugs 393 Protozoa 393 Mastigophora: Binucleata: Trypanosomidse 393 Mastigophora: Binucleata: Leptomonidae 395 Mastigophora: Spirochaetacea : Spirochaetidae 398 Life History Notes 399 Treatment of Bites 401 Control Measures 401 List of References 401 XXIX. Diseases Caused or Carried by Mites and Ticks 403 Diseases Caused by Direct Attack of Ticks and Mites 403 Diseases Carried by Mites and Ticks 411 Diseases Caused by Plant Organisms 411 Diseases of Unknown Origin 412 Diseases of Animal Origin 414 Protozoa 414 Mastigophora: Binucleata: Trypanosomidae 414 Mastigophora: Binucleata: Leptomonidae 414 Mastigophora: Spirochaetacea: Spirochaetidae 418 Telosporidia: Haemogregarinida: Haemogregarinidae 420 Summary 424 List of References 427 XXX. The Biologies and Habits of Ticks 430 Bibliographic References 438 XXXI. Control op Ticks . 440 List of References 449 XXXII. Flies and Lice in Egypt 450 The Sultan's Funeral 452 XXXIII. Insects in Relation to Packing Houses 453 Insect-Breeding Places and Their Treatment 455 Protection Against Insects 458 A Bibliography of Literature Dealing with Sanitation of Meat Packing Establishments -159 CONTENTS xvii CHAPTER PAGE XXXIV. Insect Poisoning and Miscellaneous Notes on the Transmission of Diseases by Insects J'fil Scorpion Poisoning 461 Spider Poisoning 46S Centipede Poisoning 464 Centipedes in Nasal Cavities and Alimentary Canal 466 Lepidopterous Larv/e Poisoning 466 Bee, Wasp and Ant Stings . 467 Honey Poisoning 468 Anaphylaxis 468 Poisoning from Eating Insects 469 Kissing Bugs 469 Dermatitis Caused by Beetles 469 Beetles as Carriers of Disease Germs 469 List of References 470 Summary 472 XXXV. A Tabulation of Diseases and Insect Transmission 473 Index 499 CONTENTS BY AUTHORS By W. Dwight Pierce — Bureau of Entomology PAGE How Insects Can Carry or Cause Disease 19 Some Necessary Steps in any Attempt to Prove Insect Transmission or Causation of Disease 25 A General Survey of the Needs of Entomological Sanitation in America . . 34 A General Survey of the Seriousness of Insect Borne Diseases to Armies . 43 Relations of Climate and Life, and their Bearings on the Study of Medical Ento- mology 97 Diseases Borne by Non-Biting Flies 105 Important Phases in the Life History of the Non-Biting Flies 126 The Control of the House Fly and Related Flies 153 Diseases Transmitted by Bloodsucking Flies 209 Biological Notes on the Bloodsucking Flies 223 Diseases Transmitted by Mosquitoes 247 Mosquito Control 275 Louse Borne Diseases 286 Diseases Carried by Fleas 350 Diseases Transmitted by the Cockroach ' 383 The Bedbug and Other Bloodsucking Bugs: Diseases Transmitted, Biology and Control 391 Diseases Caused or Carried by Mites and Ticks 403 Insect Poisoning and Miscellaneous Notes on the Transmission of Diseases by Insects 461 A Tabulation of Diseases and Insect Transmission 473 By W. Dwight Pierce and C. T. Greene, Bureau of Entomology What We Should Know About Mosquito Biology 2G6 By W. Dwight Pierce and Robert H. Hutchison, M.A., Bureau of Entomolopj The Life History of Human Lice 301 The Control of Human Lice 312 By B. H. Ransom, Ph.D., Zoologist, Bureau of Animal Industry Relation of Insects to the Parasitic Worms of Vertebrates 50 Bt F. C. Bishopp, B.S., Bureau of Entomology, In Charge Animal Insect Investigations Control of Flies in Barn Yards, Pig Pens and Chicken Yards 167 Myiasis, Types of Injury and Life History and Habits of Species Concerned . 175 xix XX CONTENTS BY AUTHORS PAGE Myiasis. Its Pkevention and Treatment 200 The Life History and Control of Fleas 360 The Biologies and Habits of Ticks 430 The Control of Ticks 440 By J. L. Webb, M.S., Bureau of Entomology Biology and Habits of Horse Flies 236 By G. H. Lamson, Jr., M.S., Entomologist Storrs (Conn.) Agricultural Experiment Station Lice Which Affect Domestic Animals 330 By a. N. Caudell, B.S., Bureau of Entomology: Curator of Orthoptera, U. S. National Museum Cockroaches 374 By H. a. Ballou, Ph.D., Imperial Entomologist, Barbados Flies and Lice in Egypt 450 By E. W. Laake. B.S., Bureau of Entomology Insects in Relation to Packing Houses 453 LIST OF TEXT FIGURES PAGE FIGURE -. AT /^ 1. Cross Section of Mann's Hillside Incinerator, Used at U. S. Marine Camp, QuANTico, Va. (Mann) 4^ 2 Modification of Mann's Hillside Incinerator, Adapting It to Level Ground. (Mann) *^' 3. Small Incinerator of the Ferguson Type, for Use of Small Units, and Ca- pable of Transportation. (Mann) ^^^ 4. Straddle Trench Latrines, 1 foot wide, 2 feet deep, 3 feet long, for Field Operations at Temporary Locations. (Mann) 47 5. Covered Pit Latrine Level with Ground, a Semi-Permanent Type. (Mann) 47 6. Garbage Can with Top Converted into Portable Urinal for Use in Com- pany Street at Night. (Mann) 47 7. Urine Soakage Pit, in Cross Section. (Mann's Modification from Lelean) 48 8. Chart Showing the Zones of Life Reaction to Temperature and Relative Humidity. (Pierce) ^^ 9. Suggested Curves of the Responses of Average Americans to Humid Tem- peratures. (Pierce) 10. Mouth Parts of Flies: a, suctorial type; b, biting type. (Greene) 138 IL Diagrammatic Sketch of the House Fly, Musca domestica. (Greene) .... 139 12 Abdominal Markings of Three Common House Flies: a The house fly Musca domestica; h, little house fly, Fannia caniculans; c, stable fly, Stomoxys cal- citrans (Greene). In these diagrams the relative size of the abdomen is shown. The light areas in a and b represent yellow markings and are variable in size. In fig. c the markings of the last segment may be present or absent 140 13 Ch^r^cters of a Muscid Fly Larva. (Greene.) Segment 1 is the head; 2-4 are thoracic segments; 5-11 are abdominal. Segment 11 really contains the seventh to tenth abdominal segments, the spiracles being on the eighth, the anus ^^^ 14. Larva^of^ THE Little House Fly, Fanma comcM/am. Greatly enlarged. (Howard AND Pierce, Drawing by Bradford) • 14.J 15 Dorsal View of Eighth Abdominal Segment of the Larva of Fannia canicularis. Very highly magnified. (Drawing by Bradford) ....... 143 16 Ventral View of Terminal Segments of Fannia canicidaris; the ninth and tenth segments are comprised in the small zone around the anus. Very highly magnified. (Drawing by Bradford) 17. Larva of Fannia scalaris, the Latrine Fly. Greatly magnified. (Howard and Pierce, Drawing by Bradford) " " 18. Dorsal View of Eighth Abdominal Segment of Fannia scalaris. Very highly magnified. (Drawing by Bradford) iq Ventral View of Terminal Segments of Fannia scalaris: the ninth and tenth segments are comprised in the small zone around the anus. \ ery highly magnified. (Drawing by Bradford) 20 Larva of Musca domestica: Dorsal View of Head and Prothorax. (Greene) 145 21 L.RVA OF Musca domestica: Lateral View of rER^NAL Seoments. (Okeene) The spiracles are located on the eighth abdominal .segment. The ninth and tenth segments are ventral and not very di.stinct, enclosing the anus ^io 22 Larv^ of Musca domestica: Enlarged Sketch of Right Stigmal Plate. These ■ plates are less than their breadth apart. (Greene) l-*^ 23. Lxuyx OF Stomoxys calcitrans: Enlarged Sketch of Thoracic Spiracles. (Greene) . 146 xxi xxii LIST OF TEXT FIGURES FlGtJBE PAGE 24. Larva of Stomoxi/s ct'/-;Har<';/('or a/(f/(T.voHi. (Bishopp) . 437. 87. Model Chicken Roost. (Bishopp) 446 88. A Centipede, Scolopendra morsitans. (Bradb'ord) 465 LIST OF PLATES The House or Typhoid Fly, ilusca domcstica. (ireatly enlarged. _ (Howard and Pierce, Photo by Dovener) frontispiece PAGE '"'T Screw Worms and Blow Flies. (Howard axd Pierce, Photos by Dove- ^^^ ner ) • Fig. 1. The blue bottle fly, Calliphora vomifona. " 2. The green bottle fly, Lucilia coesar. " 3. The American screw worm, Chrysomya macellaria. " 4. The black blow fly, Phormia regina. II. Eggs of the American Screw Worm, Chry.wmya macellaria. On Meat. ^^^ (Bisiiopp) III. Flies with Dangerous Habits. (Howard and Pierce, Photos by Dove- ^^^ ner) Fig. 1. A flesh fly, Sarcophaga sarracema. " 2*. The non-biting stable fly, Muscina stabulans. " 3. The lesser house fly, Fannia canicularis. " 4. The brilliant green fly, Pseudopyrellia cornicina. IV. Screw Worm Injury to a Yearling Calf. (Bishopp) 150 V Manure Box with Flytrap Attached. (Bishopp) 155 VI. Manure Spreader. (Bishopp) YII. Road Drag in Use Scraping M.^nure in a Cow Lot on a Tennessee Farm. ^^^ (Bishopp) VIII Undesirable Conditions Which Are Overcome by Use of the Maggot Tr^p a manure pile covering a large area and having httle depth Illus- trating the conditions which favor the greatest loss of nitrogen, and at the same time offer the best breeding ground for flies. (Hutchison) . . . 1o9 IX. Carcass Partly Destroyed by Larv.e of the American Screw Worm ^^^ Fly, Chrysomya macellaria. (Bishopp) 183 X. Horse Bot Flies. (Dove) ••,••••, Fig. 1. Gastrophilus intestinalis, the common bot. " 2. Gastrophilus hmmorrhoidalis, the nose fly. XI Phases of the Life Cycle of Bot Flies. (Bishopp) 18* Fig 1 Empty eggs of the cattle bot, H?/;;orffrm« /uimfa. '' " 2! Eggs of the common horse bot, Gastrophilus intestuialis. " 3! Full grown larva of Uypoderma lineata. " 4. Empty puparium of //ypo«?erma /mea/a. " 5. Empty pupanumoi Gastrophilus riitestinal IS. XII. Method of Attack by the Common Horse Bot, Gastrophilus intestinalis. ^^_ (Bishopp) • • •, Fis 1. Eggs on horse's legs. , , ■ 1 ■ j i ,. '• 2. Larvae attached to walls of stomach, showing lesions caused \n removed bots in center. XIII. Method of Attack by the Cattle Bot, or Heel Fly, Hypodemu. ^^^ lineata. (Bishopp) . . . Fiff 1 Flv ovipositing on cow s leg. '' 2. Portion of cow's back showing larva-, empty holes, and pus exudate. " 3. Heavily infested cow. XIV. Trench Prepared for Burning Carcass. (Bishopp) ^01 XXV xxvi LIST OF PLATES PLATE PAGE XV. Pup^ OF Simulium. (After Jobbins-Pomeroy) 227 Fig. 1. Respiratory filaments of pupa of Simulium vittatum. " 2. Pu{)a of Simulium re>iu.stum, in pupal case. " 3. Pui)a of Simulium bractcutum : A, Side view of filaments. " 4. V\\\rA oi Simulium jciiuimjui. " 5. Pupa of Simulium pictipea, in pupal case. All greatly enlarged. XVI. The Stable Fly, Stomoxys calcitran.i. (Bishopp) 231 Fig. 1. Eggs in straw. " 2. Pup£E in straw. " 3. Adults on leg of cow. XVII. Straw Stack Showing Proper Method of BriLoiNO Straw Stack. (Bis- hopp) 232 XVIII. The Horn Fly, Lyperosia irritans. (Bishopp) 233 Fig. 1. Flies on cow. " 2. Cow pasture showing droppings improperly left to breed flies. XIX. Tabanid^ Attacking Cattle: Tahanus phanops on cow's jaw, and T. punctifer on top of shoulder. (Bishopp) 236 XX. Tahanus punctifer. (Webb, Photos by Dovener) 238 Fig. 1. Egg masses on grass. " 2. Larva, dorsal view. " 3. Larva, lateral view. " 4. Pupa, lateral view. " 5. Pupa, ventral view. XXI. The Clothing Louse, Pediculus corporis. (Pierce and Hutchison, Photos by Dovener) 302 Fig. 1. Female, ventral view. " 2. Male, dorsal view. XXII. Eggs of the Clothing Louse, Pediculus corporis 305 Fig. 1. Mass of eggs, slightly reduced, between seams of trousers (Photo by Dovener.) " ?. Great enlargement showing eggs hatching. (Photo by Paine.) " 3. Very great enlargement showing structure of eggs with exuvise within. (Photo by Paine.) XXIII. Steam Sterilizer in Delousing Station of U. S. Army Medical Corps. The carriage is transferred along the rails in the foreground to rails leading into the other room where another carriage is seen. (Hutchison) 323 XXIV. Scaly Leg Mite on Chickens. (Bishopp) .... 406 Fig. 1. Scaly feet of chickens, caused by mite attack. " 2. Scaly leg mites, greatly enlarged. XXV. Dipping Scaly Legs of Chicken in Crude Oil. (SJishopp) 407 XXVI. The Yowl, Tic-k., Argas persicus. (Bishopp) 433 Fig. 1. Larvae under feathers of chicken. " 2. Unengorged male, ventral view; much enlarged. " 3. Female with eggs, dorsal view; greater enlargement. " 4. Unengorged female, ventral view; same enlargement as fig. 2. XXVII. The Cattle Tick, Boophilus annulatus. (Bishopp) 435 Fig. 1. Fully engorged female. " 2. Engorged female depositing eggs. XXVIII. Spraying Chicken House with Oil by Me.knts of Knapsack Spray Pump. (Bishopp) 447 SANITARY ENTOMOLOGY CHAPTER I How Insects Can Carry or Cause Disease ^ W. Dwight Pierce Our nation, as well as all our world civilization, is facing the greatest crisis in its existence in these days of reconstruction. We must con- serve human energy and keep it at its greatest possible point of effi- ciency. This means above all that questions of health are foremost today. Entomology bears a twofold relationship to health. Adequate food supply upon which human and animal health are contingent is dependent to a greater or less degree upon insect depredations. This is the side of entomology which has in the past received most of the recognition, that is, agricultural entomology. It has been generally recognized that insects also bear a direct relationship to health, but the public has more or less discounted the relationship, with the result that our public appropria- tions for the study of insects affecting crops are approximately thirty times as great as the appropriations for the study of insects affecting the health of man and animals. The present course of lectures aims to give the latest views in this almost unworked field of medical entomology, with a view toward demonstrating the necessity of obtaining a better balance in the two great phases of economic entomology. The scope of the course embraces studies of the relationship of insects to disease, the life history of the insects which cause disease, and the best methods of prevention of disease causation by insects. It is intended to be placed in the hands of the men who will conduct work along these lines, to show them why insects are dangerous, how they are dangerous, what their habits disclose as weak points subject to attack, and finally, how to go about controlling them. In my opinion the near future will see a group of professional sanitary entomologists whose services will be available to solve the insect prob- * This lecture was given on May :^0, 1918, and mimeographed copies were dis- tributed May 22. It has been considerably revised for the present course. 19 20 SANITARY ENTOMOLOGY lems of municipalities, communities, and armies, as well as household and commercial problems. Municipal entomology has already been recognized in a small wa.y by certain cities. It will become better known only by the work of entomologists themselves who are men of vision. The prob- lems involved in entomology sanitation demand an intensive and spe- cialized training which few of us received in school. If we would fit ourselves for such work it will demand great effort on our part. CLASSIFICATION OF METHODS BY WHICH INSECTS CAN CARRY OR CAUSE DISEASE Long before any one knew of causative organisms in medicine it was recognized that insects might be productive of disease. We may there- fore assume as our first category the diseases actually caused by the insects themselves. (I.) Diseases caused directly hy insects. — We must recognize, for the sake of arrangement, all pathological conditions brought about by insects whether of a serious nature or not. 1. Ento mo phobia.- — The fear of insects, both harmless and harmful, is a common ailment, amounting in many people to an obsession. I know of a young lady who became so frantic over the presence of a huge dragon fly in the automobile that the attempt to catch it led to a serious accident. Recently a serious automobile accident was caused by a bee sting. Many women become frantic at sight of large insects, and I have even seen men lose all sense of courage in the presence of an unknown species of insect. Obviously only patient and tactful educa- tion can ever cure such an obsession. 2. Annoyance and worry. — We have all probably experienced a sense of annoyance, amounting sometimes to worry, from insects. It frequently happens that the annoyance increases to the point of causing acute nervous troubles which, it is quite conceivable, might lead to insanity with certain people. Animals are frequently driven frantic by insects such as buffalo gnats, mosquitoes, and horse flies, and lose all control of themselves. We may classify these diff^crent cases of insect annoyance in accordance with the sense which perceives it and commu- nicates its sensations to the brain. In this manner we have annoyance originating through sight, memory and imagination, sound, smell, taste, and feeling. Sight worry is initiated by the occurrence of unwanted insects in home or garden, or on one's person, or by their constant swarming about until patience is exhausted and one loses control of the nerves. A recently recorded case tells of a lady whose house was badly infested with book lice and who was fast becoming a nervous wreck when HOW INSECTS CAN CARRY OR CAUSE DISEASE 21 entomological service was sought and the house freed of its pests. The constant moving of streams of ants across a floor, the sight of bedbugs or fleas, and many other common insect occurrences may cause a nervous person great perturbation. Recently a young entomologist was nau- seated and made very sick for hours by the sight of a louse infested man. Memory and imagination worry may be exemplified by the person impressed by anti-house fly propaganda, whose imagination sees on every fly multitudes of fatal disease germs. A person once injured by an insect will often experience acute revulsions of feeling on sight of another similar insect. Sound worry such as that induced by the singing of mosquitoes or the buzzing of horse flies will often lead to insomnia and in the cases of animals will cause great uneasiness. Smell worry or annoyance from insects often takes the form of great embarrassment. A few years ago in Dallas, Texas, Calosoma beetles were so numerous that people walking on the streets frequently would have one alight on them, and, in brushing the beetle off, would cause it to expel a sufl^cient quantity of liquid to make the person's presence undesirable in polite society. ]Many people are so sensitive to bedbug odors that when they sleep in infested rooms they are constantly aware of the odor and are possessed of a fear that they will be attacked by the bugs. Taste annoyance is often caused by eating berries containing bugs, or which bugs or cockroaches have contaminated. This may often cause nausea. Finally, there is the worry aroused hy contact of insects, the tingling sensation from insects crawling on the body, the peppery sting of gnats and mosquitoes, the itching sensations from vermin. Insomnia is a frequent result of such attacks. Thus as results of insect annoyance, we may have worry, nervous exhaustion, excitability, hallucinations, frenzy, insanity, nausea, insomnia and nervous chills. 3. Accidental injury to sense organs. — There are numerous cases on record of insects accidentally obtaining access to the ear or nose and causing a stoppage of these organs, or of insects flying into the eyes causing severe irritation or even blindness. Certain species of gnats are especially annoying when there is any kind of catarrhal affection of these organs. Myriapods have frequently been recorded as entering the nose of a sleeping person. 4. Poisoning. — Insects and the related arthropods may poison in a variety of ways. The bite of a tick, flea, spider, mosquito, horse fl}', etc., may cause a severe local irritation and poisoning. The poisonous 22 SANITARY ENTOMOLOGY centipedes have a poison sac opening on the front pair of legs. The scorpion stings with the tip of its tail. The bee, wasp, and ant sting with the ovipositor. Many of these injuries are very painful. Certain lepidopterous larvae are provided with barbed hairs which contain poisonous secretions, as the brown tail moth larva, and the larvas of Lagoa, Hyperchiria io., etc. Some insects emit poisonous secretions which blister (Mcloid beetles). Some of the South American honey bees {Trigona) stote poisonous honey. 5. Paralysis. — The bite of several species of ticks {Dermacentor andersoni {venustus), for example, may cause paralysis with sometimes fatal results. Some spiders, ants, bees, wasps, and caterpillars inflict such a poisonous wound that temporary paralysis of the limb follows. 6. Dermatosis. — Direct attack upon the body of men and animals, and parasitism thereon, is not unusual. We have as striking examples the dermatoses caused by lice (pediculosis), by the chigoe, the red bug (chiggers), the Dermatobia homims, creeping worms, scab and itch mites (acariasis). Many of these attacks have serious after results, as for instance an acute attack by the chigoe may result in ainhum, the loss of a toe or a foot. Many secondary diseases obtain access to the body through the skin attack of insects, 7. Myiasis and similar internal attacks. — Under this heading are to be considered cases in Avhich insects are present in the tissues of internal organs of the body. The occurrence of insects has been recorded in organs of the head, in the intestinal canal, the reproductive organs, and the body wall. When the insect is a fly the disease is called Myiasis. When a beetle is the cause, the disease is called Canthariasis, and if a lepidopterous larva is responsible it is known as Scholeciasis. Many species of flies have been recorded as occurring in the human body. These will be studied in detail in a later lesson. (II.) Diseases carried by insects. — The ways in which insects may carry diseases are very diverse, due to the great differences not only in the habits of the insects, but also of the disease organisms and the hosts. 1. Diseases carried by insects to food. — When insects carry disease germs to food or water we speak of the transmission as contaminative. Contaminative transmission of disease organisms to food by insects is naturally the simplest manner of transmission. This is necessarily done by insects which frequent excretionary substances and also visit foods, such as certain flies, ants, roaches, and beetles. It is obvious that we must look upon all insects wliich breed in fecal matter, sputum, etc., as potential disease carriers. Considerable research has already been con- ducted to prove the actual role of many species of coprophagous insects. The role of the carrier may either be mechanical or biological. HOW INSECTS CAN CARRY OR CAUSE DISEASE 23 Many disease organisms are transmitted bj insects which exercise apparently only a mechanical role. Principal among these are bacteria and certain parasitic worms. Many of the bacteria may be taken up by fly and beetle larvae, and by adult flies, beetles, roaches, and ants, and be carried on the body or ingested and passed through the body and out in the feces Avithout modification or multiplication. A number of species of parasitic worms may be taken up in the ogg stage by insects and deposited in the insect's feces. If such infested feces happen to be deposited on food, contamination and infection may conceivably follow. Certain other organisms which are carried b\' insects to food pass part of their life history in the insects. Such arc some of the nematodes that may be ingested by coprophagous insects, which in turn are eaten by the animals that serve as final hosts of tlic parasites. 2. Diseases carried hy insects to xconnds. — We can make the same division of these diseases into mechanical and biological carriage. The transmission of anthrax, leprosy, ophthalmia, and such diseases, from sore to sore or from excreta to sore is purely mechanical. When the organism passes part of its life cycle in tlie insect we might call the transmission biological. As examples of such t^-pes of transmission we may cite European relapsing fever and trench fever, louse-borne diseases which gain access to the body by the scratching in of fragments of the lice or their excreta. 3. Diseases gaining access through direct attack of insect. — ^Most of the protozoal diseases and some of the parasitic worms gain access to the body of the vertebrate host by direct inoculation, or indirectly, at the time of feeding. When the organism is taken ujt by the insect it begins its development in the insect body and finally reappears in the salivary glands or some other position adjoining the mouth parts, the inoculation occurring during the blood feast. Such is the inoculation of malaria, yellow fever, and Rocky INIountain spotted fever. But other disease organisms pass through the intestinal canal of the insect and out in the feces and yet obtain access to the wound b}^ being washed into it by body secretions of the insect, as is the case of the organism of African relapsing fever inoculated by the tick Ornithodoros moubata. WHY IT IS NECESSARY TO KXOW HOW INSECTS CARRY DISEASE In the foregoing discussion I have attempted to analyze the methods by which insects can cause or carry disease. There is also a practical side of the question. We must know the why and the wherefore and the what to do. Without a conception of the role of the insect we cannot give suf- ficient force to our arguments, or reasons for taking a particular course 24 SANITARY ENTOMOLOGY of action. For instance, if we were merely to go before the inhabitants of a Montana valley suffering from Rocky Mountain spotted fever and say : "We are going to put down this epidemic, you must dip your horses and trap all the rabbits and rodents on your place," what kind of an answer would we get? If the Public Health Service had stepped into New Orleans on the announcement of a plague case and ordered every- body to rat-proof their cellars, without further reason, they would have been driven away. If a sanitary officer reports to his superior that a certain thing must be done, requiring a considerable outlay of money and the use of a good many men, he must be able to give him a strong, forceful argu- ment to prove that he is right. Army officers, and in fact most executive officers, want brief answers. The subordinate must therefore have his information on the tip of his tongue. We have seen by the above discussion that the bites of insects must be avoided. Where disease-carrying insects are present, the greater the concentration of human beings or animals, the greater the necessity of exercising control, whether it be in a municipality, a commercial estab lishment, an army, a stock yards, or a ranch. It is incumbent upon all men charged with entomological sanitation to learn the bloodsucking fauna about them. Without a knowledge of how mosquitoes, horse flies, bedbugs, lice, stable flies, gnats, and ticks breed, one can scarcely proceed to prevent their breeding and consequently cannot protect men and animals from their attacks. One must always prevent insects from coming in contact with wounds. This is especially important in hospitals and during times of epidemics. It is at all times imperative to keep food untouched by anything in the form of insect life. Insects must not be tolerated in dwellings, no matter whether there is evidence against them or not. There is evidence against most of them. Domestic animals must likewise be kept as free as possible from insects. Some day we will recognize that stables should be as well proofed against flies as dwellings are now. There are more inducements for flies and other noxious insects around a stable than anywhere else, and the stable is therefore the direct or indirect source of many of our troubles. The measures necessary for holding down insect infestation of stable and bam yards are therefore of primary importance. But to emphasize this importance there must be back of every measure taken or recommended an argument in the form of a proof of danger if the measure is not carried out. CHAPTER II Some Necessary Steps in Any Attempt to Prove Insect Transmission or Causation of Disease ^ W. Dwight Pierce The study of the causation of disease is attracting far more attention today than it ever has in the past, but it is to be regretted that there is not a larger proportion of this effort being directed toward locating the possible intermediate hosts and invertebrate carriers. Many excellent investigations have been carried out with all other phases complete, but the question of invertebrate carriers is often left in a very indeterminate stage. The majority of the investigations which have been seriously undertaken to determine invertebrate carriers have been conducted on other continents than ours. There is a great field for investigation along these lines open to the investigators in America. In order to stimulate such research, I have attempted in this paper to set down some of the necessary steps for successful investigation. I. COOPERATION I consider essential to a thorough investigation of disease trans- mission, the establishment of a perfect working agreement and hearty cooperation between one or more physicians and diagnosticians, one or more parasitologists, and one or more entomologists. It is not safe, nor does the effort bring the proper amount of credence, when one man attempts to do the whole work. Each phase of such an investigation should be handled by an expert on that phase. The day of the solitary investigator is past and we are now in an era of group-investigations which carry with them weight and conviction. Of course certain pre- liminary steps may easily be taken by any one member of a proposed group or it may be possible that they may arrive at an advanced stage by independent work, but the time will come in each investigation when a cooperation of investigators will attain the most satisfactory results. ^ This lecture was printed in Science, n. s., vol. 50, No. 1384, pp. 135-130, August 8, 1919. 25 26 SANITARY ENTOMOLOGY II. WHERE SHOULD THE INVESTIGATIONS OF INSECT TRANSMISSION BEGIN ? There are two distinct lines of approach to this problem of insect transmission. The first is to work from the known disease and to ascer- tain by experimentation what species of insects might be concerned in its transmission. The other line of approach is to make a study of all the insects which might be involved in disease transmission and to obtain, by cultures and microscopic studies, a knowledge of the parasitic organ- isms normally and occasionally found in these insects. Working on this line of investigation, one might in time of an epidemic start with insects visiting excreta and attempt to ascertain whether the organism of the disease at that time epidemic occurs in any of these insects. The first line of investigations would arise from public necessity and probably be initiated by physicians and parasitologists, or by the sugges- tion of entomologists. The second line of investigations would probabl}^ originate as problems assigned by a professor or head of a laboratory to students or investiga- tors under his direction. It is highly desirable that such studies be com- menced in as many institutions as practicable in the near future. Such investigations will include bacteriological studies, protozoological studies, and helminthological studies, as well as investigations of the life histories of the insects, and the possible connection between them and disease transmission. III. PLAN OF OPERATION Before starting out on any line of experiment in this subject, there should be written down in concise form the facts already gleaned, on the practical problems and the theories Avhich have occurred to the various members of the group. A clearly outlined course of action should be made and be carefully discussed and then the various steps in the inves- tigations thus outlined should be read and modified to meet the changing views resulting from the experiments. The course of the work should always be kept plainly in view. Eacli step should be rigorously and skeptically scrutinized for defects. Inasmuch as the investigation from this point will consist of the answering by observation and experiment of a series of pointed ques- tions, I shall proceed with my discussion in the form of queries. Prob- ably many other vital queries will occur to the reader, but it is more than possible that he may overlook some of these if not set forth here. When each query is satisfactorily answered the problem is practically solved. STEPS TO PROVE INSECT CAUSATION OF DISEASE 27 IV. HOW SHALL WE RECORD OUR OBSERVATIONS? Undoubtedly the most satisfactory method of making a large series of records is to use some type of loose-leaf card or sheet filing system. By such means one can always keep in an orderly arrangement all the facts so far obtained. In the case of investigations of the causation of a given disease, one of the most satisfactory methods which has been used for recording observations is to prepare a little blank booklet, which will fit the filing system, in large quantities, each book to represent a case. This book should contain pages for each phase of the question, with blanks covering all kinds of minutias about this phase. The whole series of observations can be tabulated for each point. V. HOW CAN AN INSECT BE INVOLVED IN DISEASE TRANSMISSION.'' Insects may be involved in disease transmission either by the trans- mission of an organism or the inoculation of a toxin, or they may be an intermediate host in the life cycle of an organism, but not come directly in contact with the final host. 1. What Kind of Organisms Can Insects Carry? It has been demonstrated that insects can carry bacteria, fungi, many types of protozoa, and many species of parasitic worms, and also that certain species of insects may be instrumental in carrying eggs of other species of insects which cause disease. 2. In What Manner May Insect Toxins Bring About Disease? Many species of insects which bite inoculate at the time of the bite a toxin which may at times cause serious trouble. Some invertebrates inoculate the toxin by means of the mouth, some by means of a claw, some by means of a caudal appendage, others by means of the ovipositor. In some cases the invertebrate penetrates the skin with its mouth parts and as long as it is adhering, toxins are created which may in certain cases cause severe paralysis or death. The acci- dental eating of certain insects in food will cause poisoning because of the toxins contained in the bodies of the insects. It is believed, but not yet satisfactorily demonstrated, that the pollution of food by the excreta of certain insects may cause certain nutritional diseases. The presence of certain insects in the tissues causes severe irritations and often the formation of toxins. 28 SANITARY ENTOMOLOGY S. Can Insects Themselves Cause Disease? Many species of insects are known to live parasitically upon the bodies of man and animals and by their constant sucking of blood or gnawing, cause skin diseases. Other species of insects habitually lay their eggs on or in the flesh and breed commonly or exclusively in living flesh, causing a destruction of the tissues. Many species of insects are depen- dent upon mammalian blood for the necessary nutriment to bring about reproduction. Some insect larvae are bloodsuckers. It is not at all uncommon for insect larvae to be ingested in food and for them to con- tinue their development in the intestines or other organs, often at the expense of the tissues. In some parts of the world insects are eaten as food by the natives, sometimes in a raw state, and it is not uncommon in such case for the natives to be infected with parasitic worms which pass their intermediate stages in the bodies of these insects. 4. Where May Insects Obtain the Organisms which Cause (Disease? Disease organisms may be taken up by insects directly from the blood of an infected host, or they may be obtained by contact with infected surfaces of the body or taken up from the feces or other excretions of an infected host. The insect may take up the organisms from these excretions either in its larval or its adult stage. 5. How Can the Insect Transmit the Organism? The organism may be transmitted by the insect by direct inoculation through the proboscis, involving the active movement of the parasite, or the passive transmission of the parasite in the reflex action which takes place in the sucking of blood. The organism may be externally carried on the beak of the insect and mechanically transmitted at the time of sucking. It may be located in the mouth parts of the insect and burrow through at the same time the insect is feeding. It may be in a passive state on the insect and become stimulated to attack the host when it comes in contact with the warm body. The organism may be regurgitated by the insect on the bod}' of its host and obtain entrance by its own activity, or by being scratched in or by being licked up by the host. On the other hand, the organism may pass through the insect, and pass out in its feces, or in Malpighian excretions. It may be washed into the wound made by the sucking of the insect, by fluids excreted at the time of the feeding. It may remain in the feces on the host and ultimately be scratched in or licked up by the host. The organism may be taken up by the insect and never normally pass Out of the insect, but be inoculated by the crushing of its invertebrate STEPS TO PROVE INSECT CAUSATION OF DISEASE 29 host upon the body, and the scratching of infected portions of the insect's body into the blood ; or may be transmitted only by the ingestion of the insect itself by its vertebrate host, or accidentally by some grazing animal. In fact quite a series of disease organisms find their way into their hosts because of the habit of the animals of feeding upon insects. 6. What Is the Course of the Organism in the Insect? If the organism is taken up by the insect in its larval stage, it may pass directly through the larva and out in its feces and may quite con- ceivably pass in this manner through insect after insect larva before it finally finds a vertebrate host. The organism may be taken up by the larva and remain dormant in some portion of the larva's anatomy, or on the other hand, it might undergo considerable development and multipli- cation in the larva and remain there through all the metamorphosis of the insect until the latter arrives at maturity, at which time development of the organism may begin or may continue. Upon being taken up in the blood by the bite of the insect, the organ- ism may lodge in tlie esophagus and carry out all its metamorphosis there, or in some of the organs of the head and find its way into the salivary glands and through the salivary secretions into a new host. It may, on the other hand, pass back into the gut, or into the stomach ; from the stomach its path may lead in many directions. It may pass on in its course of development into the rectum and out in the feces, or it may enter the fatty bodies, or pass into the general cavity of the insect, or it may migrate forward into the esophagus and into the labrum ; and it may pass into the ^Malpighian tubules, or into the ovaries. The organism may enter the eggs and remain therein through their development into the larA'ae, nymphs or adults, and be transmitted at some stage of the development of the second generation. Some diseases can pass on even to the third generation. 7. What Is the Course of the Organism on Leaving the Insect? The organism may leave the insect in the saliva and immediately enter the feeding puncture. It may bore through the labium of the insect at tlie time of feeding and enter the puncture. It may leave the rectum of the insect, or the Malpighian glands and be washed into the puncture by means of the secretions of the coxal glands, or some other excretions made at the time of feeding. It may be excreted in Malpighian secre- tions, or rectal feces, or regurgitated in vomit, and may lie dormant on the skin of the host, or on the food of the host, until it is scratched into the blood, or is taken into the mouth. 30 SANITARY ENTOMOLOGY On the other hand, it may be possible that the organism requires another host after the insect, and before it reaches its final host. There are cases on record of the insect being the first host, and two or three vertebrates in succession being hosts of later stages. VI. WHAT IS KNOWN ABOUT THE DISEASE TO BE INVESTIGATED? It is a primary essential that all the workers be able to recognize the disease which they are trying to study and that they be fully informed about it, so that they may be able to grasp possible solutions of their problem. They will, therefore, seek first to answer the following ques- tions : 1. What is the history of the disease and how long has it been known.'' How serious has it been? 2. What is its distribution? 3. Does it occur in pandemic, epidemic, endemic or sporadic form? 4. In what seasons of the year is it most prevalent? 5. Is there any apparent relationship between its distribution and the physical, biological or climatic features of the countries where it occurs? 6. Does it affect any particular group, occupation, sex, age, race or nation of people, or any particular species of animal? 7. May an}^ wild animal be considered as a reservoir? 8. Has immunity or difference of susceptibility been recognized and under what circumstances? 9. What are the symptoms of the disease? 10. What is known regarding immuno-chemistry and bacteriology of the disease? 11. What have autopsies shown? 12. What treatment has been designated? 13. What is known or suspected about its causation and dissemina- tion? What organisms have been connected with it? 14. What possible theories can be advanced to account for its causation and dissemination? A little time spent in collecting these facts may save much effort later. VII. WHAT INSECTS SHOULD BE INVESTIGATED? A thorough entomological study of this question may prove a valuable short cut to the investigation. Many insects will be eliminated by the entomologist before he has finished his preliminary work. He will attempt to answer the following and many other questions and will probably have to answer them to the satisfaction of all his fellow workers. STEPS TO PROVE INSECT CAUSATION OF DISEASE 31 1. What insects coincide in distribution with the general distribution of the disease? 2. What insects occur in peculiar habitats of the disease? 3. What bloodsucking insects occur in the locality under investi- gation ? 4. What is the relative abundance of these insects? 5. Is there a coincidence between the season of abundance of any of these insects and of the disease? 6. What insects occur in the homes, nests, or haunts of infected hosts? 7. What insects are found on infected hosts? 8. What insects occur in the working quarters of the patients ? 9. What insects would be most apt to affect the particular group of hosts most susceptible? 10. What insects breed in or frequent the excreta of the hosts? 11. What insects are found at the food of the hosts? 12. What insects are found at the sources of the food of the hosts, such as the milk? Vni. WHAT IS NECESSARY IN THE TRANSMISSION EXPERIMENTS? The investigations which have preceded will have narrowed the ques- tion doAvn to certain species or groups of insects which need to be critically studied. All of those insects which come in contact with the blood or mucous membranes of the patient, or the food of the patient, or the feces of the patient, must be given special attention. At this point the bacteriologist, protozoologist, or the lielminthologist finds his special work beginning. There will be many points which must be worked out by cooperation of the parasitologist and entomologist. Considering first the bloodsucking insects, it is necessary to deter- mine: 1. Can. the particular insect take up the organism with the blood? 2. Does the organism pass into the intestinal canal or does it stop at some point en route? 3. To what extent is the organism digested by the insect? 4. In what organs of the insect can the parasite be demonstrated from day to day? 5. Are any changes in the organism demonstrable? 6. What path does the organism seem to follow in the insect's body from day to day? 7. Does this movement of the organism suggest whether the trans- mission is by inoculation or does it suggest that the organism will pass out of the body in some of tlic excreta? 32 SANITARY ENTOMOLOGY 8. Can the organism be demonstrated in the mouth parts of the insect at the time of feeding? 9. Can the organism be found in any of the excretions of the insect? 10. How long is it before the organism reaches the mouth or the rectum ? 11. What is the earliest date at which it can be found in the feces ? 12. WHiat is the earliest date at which infectivity of the host can be obtained by the sucking of the blood? 13. What is the earliest date at which infectivity can be obtained by scratching in of the feces or portions of the insect? 14. Can infection be obtained by either natural or artificial inocula- tion without demonstration of the organism? 15. Is the infective organism, contagium or virus filterable? 16. Can the virus or organism be transmitted hereditarily by the insect ? 17. At what stage of development in the second generation does hereditary transmission become possible? 18. Can the organism be taken up by the immature stages, feeding in infected excreta? 19. Can the organism be taken up by immature stages of an inverte- brate feeding on the host? 20. How long can the immature forms of the invertebrate, infected by whatsoever manner, retain the organism in their system? 21. Does the organism stay in the insect during metamorphosis? 22. Does the organism undergo any changes preceding or following metamorphosis of its invertebrate host? 23. At what stage in the metaiiciorphosis does the insect begin to be infective after taking up such organisms? 24. How long can the insect remain infected and infective? IX. HOW SHOULD EXPERIMENTAL INSECTS BE HANDLED? A large proportion of the failures in studies of insect transmission in the past have arisen from improper handling of the insects. The breeding and handling of the insects is an art in itself, just as is the culturing of bacteria or protozoa. In fact, there are more diverse requirements for handling insects of different species than can be found elsewhere in the animal kingdom. 1. What rmist he known about the insect before beginning trans- mission experiments? The normal conditions of life of the insect must be ascertained : — its STEPS TO PROVE INSECT CAUSATION OF DISEASE 33 reactions to heat and cold, moisture and dryness, disturbances, color, light, odor ; its food, and the proper condition thereof ; its methods of reproduction, and what food is necessary for reproduction ; if soil should be provided, and what conditions it should be in ; if water should be provided, and whether this water should be alkaline or acid, clear or containing foreign matter, and in such case what type of foreign matter; whether the water should be still or in motion, warm, moderate or cold. 2. What type of breeding cage should be used? A breeding cage must be used which will most nearly enable the experimenter to keep the insects under control and yet reproduce essen- tial conditions for maintaining normal, healthy life of the insects and normal reproduction. Much of this information is available in entomo- logical literature. INIany insects probably involved in disease transmis- sion have not been properly studied and breeding technique is yet to be worked out. 3. Water is necessary in some form in practically all insect breed- ing. There are more failures to properly breed insects traceable to im- proper humidity, or to the lack of moisture in the proper form for the insects to drink. Much detailed observation may be necessary to obtain this important information in the case of many insects. 4. There is a combination of temperature and humidity most favor- able for life, for each species, and differing from one species to another. 5. The food of an insect must be in a particular condition in order to obtain normal breeding. It may require a certain degree of immaturity, ripeness, or fermentation. It may require a certain degree of desicca- tion. Many other details must be attended to by each specialist involved in the investigation, and we probably have yet to see a single disease problem which has been completely rounded out and solved for the future generations. CHAPTER III A General Survey of the Needs of Entomological Sanitation in America ^ W. Dwight Pierce Notwithstanding the great amount of publicity which has been given the Anti-fly Campaign, one will find throughout our land a rather general disregard of the danger from flies. Certain newspapers keep the subject annually before their readers, but on the whole, public co- operation is slight, A few cities and communities have definitely organ- ized mosquito control work, and the Public Health Service has done a wonderful amount of work in organizing such efforts. From an ento- mological standpoint our nation is not sanitary. The reason lies in the fact that the public does not yet realize that insects can and do carry disease. Science has apparently not put forward the idea in such a manner that it has gripped the average person. Until we do this we cannot expect public cooperation in the attempt to put down insect- spread diseases. The problems we have to meet may be divided in several diff^erent manners. We may separate them into problems of municipalities, towns and villages, and rural communities. We ma^^ look at them from the standpoint of the farm, the home, the market, the factory, and the institution. They may be sorted out as problems of drainage, waste disposal, screening, animal control, etc. Of course we have a greater diversity of entomological control prob- lems in a municipality, but we also have more people who give attention to matters of health in a city, and who would complain against un- healthful conditions. On the other hand, while the problems of the rural community and town are fewer, the insect conditions often become greatly aggravated because of total carelessness as to sanitation. This careless- ness in small towns and farms is usually due either to ignorance or lack of organized efi'ort for community betterment. The field of the sanitary entomologist who desires to tread virgin soil is therefore to solve the ways and means of obtaining better fly and mosquito conditions in rural communities. Educational work must be ' This lecture was mimeographed and circulated to the class in January and ap- peared in parts in The American City, for February and March, 1919. 34 NEEDS OF ENTOMOLOGICAL SANITATION IN AMERICA 35 carried out which will be of such nature that it will bring results. We have the theories and the scientific facts but we must give the public practical demonstrations that freedom from insect pests means reduced sickness. Any person informed on this subject who has traveled much in rural sections of this country' and seen the unobstructed entrance of myriads of house-flies to the dwellings, especially the kitchens and dining rooms, and then has stepped outside and within a few feet found the open privies breeding these flies, cannot help but feel a sickening sensation and a revulsion toward eating anything that the flies could have polluted. It is not at all uncommon in rural sections to see babies exposed to the unre- stricted visits of flies, and their milk bottles covered with them. The writer has been informed over and over by physicians in small towns that when infantile diarrhea or any other intestinal complaint visits a town it makes the rounds of every infant in the town, unless perchance, some mother is more advanced in her knowledge of such matters and keeps her baby constantly screened. When typhoid fever and dysentery visit towns with open privies and unscreened houses or hotels only the more cautious and more resistant escape. Such communities off*er every conceivable opportunity for the spread of diseases by flies. THE INSANITARY FARM For fifteen years the writer has traveled extensively in rural communi- ties, principally in the Southern States, where insanitary methods, if existent, aggravate disease conditions because of the more favorable climate and greater number of maladies present. We may picture, there- fore, a few of the conditions which have been repeatedly seen in these travels, in order the better to show the problems to be met. We shall not claim that these pictures represent the predominant, or the usual, or the average condition. Let it sufl^ce that they exist suflSciently often to make them worthy of serious attention. The farm we will describe has been seen countless times. The house has no screens on the windows, in fact, often has no window panes, or may have wooden windows which are open all day. The house is one- storied with an outside chimney, and an open fireplace. The chimney and fireplace offer excellent day hiding places for mosquitoes, which are abundant if there is a slough or bayou nearby. The house is built on stumps or pillars raised above the ground. The pigs and Chickens, dogs and cats, wander freely underneath. The house has a great open hall- way through the middle, separating the bedrooms from the living rooms. On account of tlic numerous flea-breeding animals which pass under the house, fleas are not at all uncommon in the house. The well is usually 36 SANITARY ENTOMOLOGY open and built into the back portion of tlic porch. IMosquitoes breed in it. There is a poorly constructed, dilapidated privy for the women not far from the house, but the men have none, or if they do, it is not fit to enter. They usually defecate in the open, in the fields or draws, or in a woodland patch. Tiie barn is roughly constructed. Tlie manure is piled in a great pile beside the barn, and breeds multitudes of flies. The stable floor is urine- and manure-soaked and affords excellent fly-breeding quarters. Naturally, I have described the worst common type of farm, because on this must be built the structure for better sanitation in farm life. In many cases a large number of such places may exist on a single large plantation, for the use of the tenants. In such cases a single man is responsible, who himself lives in a house with all modern sanitary conveniences. The problem of the sanitarian and the sanitary entomojogist is to prove to the individual farmer and to the planter landlord the financial value of better sanitation. The planter must be shown that inasmuch as the efficiency hours of his tenants are increased, in proportion will their products be increased, and in like manner his rental, especially where the rental is based on certain proportions of the crop yield. He must see that reduction of mosquitoes means reduction of malaria inci- dence, that reduction of flies reduces the incidence of typhoid, dysentery, diarrhea, and other intestinal complaints, and that as the sickness rate on the plantation is decreased the labor output is increased. It will do us no good to theorize if we do not set down clearly the ways and means of accomplishing this greater farm output by reducing fly and mosquito breeding. In the present course of lectures will be found the proofs which have accumulated against these various insects, brief statements of how these insects live, and detailed plans of the approved methods of control. Fortified with this ammunition and more which he will personally gain, the sanitary entomologist must fight for better sanitation. HOW TO IMPROVE FARM SANITATION At this time, however, we may in brief state a few measures which should be taken on every farm in order to accomplish greater farm labor efficiency and improve the health of the household and of the animals. 1. The windows and doors should he screened against flies and mosquitoes. During the months that fires are not used the chimneys should have a screen over the top and the fireplace screened. If wire screening cannot be afforded, mosquito bars can be used. In the majority of cases the expenditure of the necessary amount of money to properly NEEDS OF ENTO:\IOLOGICAL SANITATION IN AMERICA 37 screen the place will be offset by a greater reduction in doctor's bills for the women and children at least. 2. Where there are many children passing in and out flies will get in. The children should he taught to use fly swatters. No flies should ever be allowed to remain in the kitchen and dining rooms. Flies which visit food will deposit on it any disease organisms they have picked up. If the Avater is pure, the fly is about the only common means of conveying intestinal diseases to the family. 3. Unless the babies and small children are kept indoors in screened rooms, the helpless children should have a mosquito bar over the carriage or basket so as to protect them from \^ies. This is absolutely essential if there is any sickness in the neighborhood. 4. There shoidd be installed sanitary -pit or bucket privies such as are recommended by the Public Health Service. Both men and women should be provided with such, and it should be a. rule of every farm that indiscriminate defecation is absolutely forbidden. As many farms are quite large the most feasible plan would be to place at various places over the farm where they would be most convenient and best protected, some type of latrine, such as is used by armies, or better still a perma- nent privy. 5. The well should be kept covered to prevent as far as possible mosquito breeding and contamination. 6. The foundations of the house should be boarded up to prevent the access of animals and to eliminate a favorite mosquito hiding place. The ground around the house should be so drained that water will not flow under the house except in case of 'heavy rains, and in such cases will quickly drain off from under the house. 7. All ditches, ponds, streams, and bayous on the farm should have the banks kept clear of obstructions io the free flow of the water. There should not be any tree stumps, trees, roots, weeds, or logs in the stream. The banks should not have overhanging ledges, or puddle pits. Per- manent ponds and lakes might be stocked with mosquito-eating fish. Places which habitually form puddles after rains should be filled and drained. 8. The barns should have hard packed dirt floors or cement floors. All manure should be removed daily from the barn. If possible the manure should be spread while fresh on fields lying fallow. Othenvise the manure should be piled in tightly packed stacks or on platforms over a cement basin containing water, in order to drown the fly larvae migrating for pupation. 9. The garbage should he fed to pigs, preferably in sanitary feeding stalls as described by Bishopp in the lecture on the control of flies in barn yards, pig pens and chicken yards (Chapter XI). 38 SANITARY ENTOMOLOGY 10. State Boards of Health should follow the California plan and forbid the marketing of fruit dried on farms with open sewage, or where exposed to visits of flies. THE INSAXITARY TOWN In these same travels in which so many insanitary farms were seen, the writer has sojourned in or passed through many towns which might be described as follows: The streets are unpaved and are littered from one end to the other with papers, cans, and the accumulation of months of manure droppings, and are altogether filthy and unattractive. The removal of trash is nobody's business. The grocery stores and meat markets are unscreened and have open doors. The food is covered with flies. Farmers drive up and buy a side of salt pork or other meat, throw it into the pit of their wagon, uncovered, and drive down the dusty road, with a swarm of flies hovering over the meat. The small lunch rooms where the visiting farmer eats his noon or evening repast are dirty and full of flies. The stores have privies in the rear which are filthy and an offense to any decent person. Flies abound. Chickens and pigs wander unrestricted through the streets and are often found feeding under the privies. The hotel dining rooms and kitchens are always full of flies and are usually but a short distance from filthy privies, and flies are constantly passing back and forth. Cockroaches are served in the food and wander unrestricted everywhere. The bedding is often unclean and has been slept in by some one else. Bedbugs are not uncommon. The water pitchers contain mosquito wrigglers. The cis- terns behind each house are unscreened, and contain rain water, full of mosquitoes. The livery stable has great piles of manure in the stable yards and sometimes right out on the sidewalk. Sometimes the town is a little bigger and the people have become more civilized and installed interior plumbing, which empties the sewage into a ditch which runs down to a stream from which cattle drink, or quite often this sewage empties into the gutter on the street and fills the air with filthy odors. Such is not an uncommon thing in America. Only a few years ago we could have pointed out quite a number of cities in the 100,000 class with open sewage. These small towns are often rat infested, and one can easily see the danger should an outbreak of plague, which is transmitted by the rat flea, get a start in such a town, by the advent of a plague infested rat. HOW TO IMPROVE SANITATION 1. Organize the community for better sanitation, and call in an expert of the Public Health Service, which is giving a great deal of NEEDS OF ENTOMOLOGICAL SANITATION IN AMERICA 39 attention to cooperative health work. In Russia, such organizations were springing up all over the land before that country became submerged in its present chaos. 2. Conduct a health publicity campaign. 3. Teach better sanitation in the schools and organize the children for clean-up work. 4. Require the screening of all stores selling food, and of all hotels and restaurants dispensing food. Do not allow food to be handled in such a way that it will attract great quantities of flies. 5. Require private stables to place manure in fl\'-tight boxes and to have same removed every 7 to 10 days. 6. Require livery stables to remove all accumulations of manure daily from the town limits. 7. Require the burning, feeding or removal of all garbage twice a week from homes and daily from hotels. 8. If garbage is hauled away and dumped the town should arrange for its daily incineration. 9. Require throughout the town limits, depending upon conditions, either sanitary plumbing and sewer connection, or sanitary box or pail privies. Do not allow pit privies or insanitary ones of any type. Do away as soon as possible with open sewer drainage, installing sewer pipe. Install sewage septic tanks of size adequate for the town. If there are no sewers laid it may be possible to arrange for individual installation of simple septic tanks. 10. Do not allow pigs and chickens to have access to privies. 11. Do not permit general roving of pigs, stock, chickens, etc., on the town streets. 12. Keep all ditches and waterways in the town free of obstruction, and if mosquitoes are breeding, have an oiling squad. 13. Fix strict penalties against defecation on streets, alleys, and vacant lots. 14. Install a town comfort station for strangers and people from the country. SANITARY PROBLEMS OF CITIES The sanitary entomological problems are multiple in large cities, and such that it would be an excellent practice to employ at least a consult- ing entomologist in all large cities. As a matter of fact many cities should have quite a corps of practical sanitary entomologists engaged primarily for this type of work. City markets where meats, fish and all kinds of vegetables and produce are exposed for sale, are very attractive places for flies, and in many large cities there is gross neglect along these lines. 40 SANITARY ENTOMOLOGY Sanitarj'^ inspectors need to exercise considerable vigilance in checking up obedience to ordinances relating to removal of trash, garbage, manure, excreta ; installation of sewage or sanitary privies ; proper sanitation among construction gangs ; nuisances arising from stables, factories, sewage and garba'ge disposal plants, packing houses, stock yards, etc. Many manufacturing plants have waste products which are very attrac- tive to insects. Insect conditions in restaurants, boarding houses and hotels should be frequently checked up. Anti-fly and anti-mosquito propaganda should be conducted annually in every city until the people are so well educated to the necessity thereof that propaganda will no longer be necessary. The sanitary department of large cities should directly supervise mosquito suppression within its bounds. ENTOMOLOGICAI. REQUIREMENTS OF MUNICIPAI. SANITATION The following points should be covered by ordinance in all large cities desirous of obtaining satisfactory sanitation. Not enough attention has been given by city health authorities to the insect side of their sanitary problems. 1. All foodstuffs, which are eaten raw, all raw meats, fish, birds, cooked foods, bread, cheese, dried fruits, etc., must be kept under cover of glass or screen or otherwise protected from insects, in all markets, stores, street stands, hotels, restaurants and boarding houses. Flies must not be allowed to congregate around food stalls. Cockroaches must be eliminated from all hotels, restaurants and boarding houses. Foods infested by insects should be subject to condemnation and destruction. Insect contamination of food is dangerous. 2. Hotels, public institutions, and lodging houses shall be required to keep their premises free of bedbugs. Bedbugs carry disease. 3. All school children shall be inspected at the beginning of each new school year for head lice, and oftener if circumstances warrant. In case the children are infested they should be isolated and sent to some clinic whei'e they can be freed of the lice. All prisoners, patients in hospitals, and applicants at municipal lodging houses should be in- spected for head, body, and crab lice, and if infested should be bathed and their clothing condemned or cleaned. Lice carry many diseases and every opportunity should be taken which will enable the authorities to reduce their incidence. 4. All livery stables shall be required to remove all manure to the country daily, unless specified places for dumping are set aside. All private stables should be provided with a fly-proof box or a maggot- NEEDS OF ENTOMOLOGICAL SANITATION IN AMERICA 41 trap platform for the storage of manure and should have the manure removed at least every 10 days. 5. Garbage should be removed daily from all places where it accu- mulates in large quantities, and two or three times a week from private residences. All garbage awaiting removal should be kept in closed cans. Garbage must not be dumped within the city limits unless it is dumped on incinerators where fires will soon consume it. These require- ments are necessary to keep down fly breeding. 6. Tin cans, bottles, and receptacles which will hold water, must not be allowed to accumulate in back yards, alleys or vacant lots, nor may the}^ be dumped within the city limits or near residential sections in the suburbs, because they furnish excellent breeding quarters for mosquitoes. 7. The city should be connected for sewers as far into the suburbs as practicable, and all suburban properties not so connected should be required to install fly-jDroof cesspools, or septic tanks, or to arrange by neighborhoods for independent sewage with a common septic tank; or in the absence of water and necessary plumbing, to install sanitary privies, and be required to have all excreta removed once a week to an incinerator or other type of refuse disposal plant. Open vault privies should not be permitted in the city. Indiscriminate defecation on streets, alleys, vacant lots, etc., should be strictly forbidden and punishable by law. 8. Packing houses, candy factories, syrup factories, and all other manufacturing institutions producing food products should be required to screen windows and entrances, and to use fly traps in such a way as to minimize to the utmost the access of flies and other insects to the food products. Especial attention should be given to the prevention of insect breeding on such premises. INDUSTRIAL SANITATION Many industries have important entomological sanitary problems in the preservation of their products from insect contamination and in the eff'orts to conform to sanitary regulations. There are many times when they would be able to use the services of a consulting sanitary entomologist to advantage. The keynote of industry today is the prevention or utilization of waste. Insect depredations on food products cause waste because the public does not want polluted food, and because sanitary inspectors arc becoming more and more alive to the menace to health from insect pol- luted foods. It is not generally understood that the presence of weevils and worms in cereal foods may do more than destroy the food. The evidence is 42 SANITARY ENTOMOLOGY growing against these insects from the sanitary standpoint. Some of these insects contain substances in their bodies which are highly toxic, as for instance Sitophilus granarius, tlie granary weevil, contains the poisonous substance cantharidin. There are numerous instances of the sickening of animals from eating weevily grain. Still more important is the fact that where grain is accessible both to rodents and insects, certain parasitic worms pass out in the feces of the rodent in the egg stage, are eaten by the insect larvae in the grain, pass part of their life cycle in the insect, and the insect is then possibly eaten by a rodent, in which the worm completes its life cycle ; or sometimes in our breakfast foods we eat these parasitized insects and become infected with the worms. For example, the rat tapeworm, Hymenolepis diminuta (Rudolphi) infests various species of rats, but sometimes is found in man. Joyeux has proved that its commonest intermediate host is the meal moth, Asopia farinalis, which becomes infected by eating the tapeworm eggs, in the larval stage. Grassi and Rovelli found the cysticercoid in the larva and adult of this moth and also in the earwig, Anisolabis annulipes and the beetles Akis spinosa and Scaurus striatus. Joyeux found that the adults of the granary beetle, Tenehrio molitor, easily took up the eggs. A cysticercoid or larval stage resembling the mouse tapeworm Hymenolepis microstoma (Dujardin) has been found by Grassi and Rovelli in the beetle Tenehrio molitor. The whole problem, therefore, of the control of stored food product insects is of vital importance to the manufacturers of food. Syrup factories, sugar mills and refineries, ice cream factories, cream- eries, and candy factories offer great attractions to flies which may alight on the exposed products and deposit with their feet, or in their vomit or excreta, germs of disease taken up elsewhere, perhaps days before when the fly was a larva breeding in excrement, and these germs may find the sweets excellent culture media for extensive growth. Extraor- dinary means must be devised to keep flies away from such products. Packinghouses offer abundant attractions to many kinds of insects, many of which are serious disease carriers. Railroad trains are the means of conveying from place to place disease-carrying mosquitoes, flies, roaches, fleas, lice, bedbugs, and mites. Fumigation of railway cars is an essential entomological control measure. Dairies are often found to be the foci of the spread of typhoid fever, and knowing the propensity of the house fly we can sec how readily it can carry the organisms from the stools of a sick person to the milk pails in the dairy. There needs to be rigid control of flies in all dairies. These are but examples of many industries which have problems in sanitary entomology. CHAPTER IV A General Survey of the Seriousness of Insect-Borne Diseases to Armies * W. Dwight Pierce As this course of study is directed primarily toward obtaining a thorough knowledge of the relations of insects to diseases of men and the measures which must be taken to prevent these diseases, it is eminently proper for us to make a survey of the "insect problems which confront the greatest aggregations of men, the modern army. From a study of mili- tary sanitation methods we may learn much which we need to know in practical municipal problems. Military methods are based on the neces- sity of quick returns and emergency' efficiency, from which are built up in permanent establishments more perfect measures. The discussion of military entomology immediately falls into two very distinct lines: first, the army training and concentration camps, and second, the active service camps and battle conditions. Before the location of the average training camp, we may assume that it is possible to deliberate more or less on the desirabilit}' of one or more sites and that in a general way drinking water and general health conditions are considered. Not infrequently some other consideration will outweigh sanitation, as when it is considered essential to place a camp near a certain city or on a certain waterway or railway. In such cases of expediency, we are quite likely to find sanitation a serious problem from the outset. The camp site is selected because of some important reason. From an entomologist's viewpoint a number of outstanding questions immediately arise as to this site. Is the ground open or wooded, level or sloping and well drained? Are there water holes, running streams, or swamps in the camp area or nearby.'' Are there farmhouses, stables, or other buildings on the site and what is the entomological situation in these buildings? What disease-carrying insects are naturally breeding about the camp site? If there has been any contagious disease of man or animals in the community before the camp was located, the entomolo- gist's concern is the greater. He should if possible learn the focus of * This lecture was originally presented May 27, 1918, and distributed the same day. It has been revised for the present edition. 43 44 SANITARY ENTO]\IOLOGY that disease and the insect conditions of that focus. The original health conditions on the site may have a distinct bearing on later events. Often the first arrivals at the camp site are contractors with multi- tudes of laborers and animals collected from everywhere, and from every stratum of society. There arc few hygienic arrangements for these men. In fact, the contractors are aiming to obtain as large profits as possible, and therefore hold down the expenses for sanitary waste disposal. Some among these laborers are almost certain to bring lice, bedbugs, fleas, and possibly also scabies mites, on their bodies and clothes. Thrown together indiscriminately in hastily constructed barracks, there is soon a general distribution of vermin. Their animals are quite likely to be infected with scabies mites and possibly other mites, and with bots and ticks. The undisciplined assembling of many animals and carelessness about manure disposal offers great attractiveness to all flies and insects attracted by animals. It is probable that many dogs accompany the laborers and contribute their quota of fleas. It is almost impossible with crude, unedu- cated laboring men to get them to maintain sanitary conditions. Indis- criminate defecation, the scattering of garbage, the accumulation of manure, personal uncleanliness, all contribute to make contractor camps sanitary sore spots. Sooner or later the sanitarians arrive on the spot, very likely with a squad or company of raw untrained labor troops, and the clean-up begins. We can expect a constant lack of coordination between the military and the civilian. As for example, at one camp the sanitary officers had constructed drainage ditches to carry off* surplus standing water, but the laborers persisted in throwing scraps of wood, underbrush and waste into the ditches so that they were of no avail, or rather so that they formed traps for water pools. During the transition period when the camp is part civilian and part military there will be two very diff'erent types of conditions existing side by side, one good, one bad. Of course the army sanitarians have supervision over these civilian camps, but they find difficulty in enforcing sanitation. When a camp is placed like Camp Humphreys, Virginia, on a tongue of land between two shallow bays of water that are known to fill up with vegetation, and which furnish breeding places for millions of mosquitoes, and with typical swamp lands at the heads of these bays, we may readily see that the task of the sanitary officer is not an easy one. These bays are moreover at tidal level and the daily fluctuations of the water add complications to the drainage problem. Each individual camp, wherever located, will present its own type of problems, and necessitates an early and thorough entomological survey. The tremendous speed of construction and the rapid arrivals of fresh SERIOUSNESS OF INSECT-BORNE DISEASES TO ARMIES 45 contingents of troops and animals in a new army camp make the first months of the entomological sanitarian very busy ones. Common sense is one of the primary essentials in meeting the exigencies of the situation. The possibility of mosquito breeding must be kept at a minimum in spite of temporary drainage, multitudes of borrow pits, tree stumps, fire-water barrels, etc. A system of manure, garbage, refuse, and fecal disposal is of necessity hastily devised and must keep pace with the increasing numbers of men and animals. This waste disposal is handled by special units and the sanitarian acts only in an advisory capacity. He needs therefore to be very vigilant in his inspections. Army camps nowadays grow in such marvelous proportions that past experiences are of little avail. The man on the ground must be avcII versed in the principles of entomological sanitation and must use his judgment for all it is worth. The constant accessions in troops and raw recruits call for constant scouting and prophylaxis to prevent admission of vermin. The work against vermin almost necessitates a specialist to take care of it alone. In fact it were best if three entomologists were located in each camp, one looking after the suppression of water and moist earth breeding insects, one looking after the suppression of fecal, waste, and manure breeding insects, and the third handling the vermin of the person and the barracks. So serious is the vermin problem in all armies that elaborate measures have to be taken to combat it. The Germans developed great vacuum tubes that will contain an entire railroad coach. The Russians, and then other nations, developed bath trains sufficient to handle the cleansing of thousands of men a day. The Russians and Roumanians developed sod houses for heat sterilization of clothing. Heat and steam sterilizing plants of many types have been devised. A tremendous amount of experimen- tation has been directed toward chemical cleansing of the clothing. The destruction of waste is such an acute problem that many types of incinerators have resulted (see figs. 1, 2, 3), but as a camp becomes permanently organized the sewage s^^stem does away with many of the early difficulties. Permanent incinerators, well kept drainage sj'stems, organized removal of the manure, and disposal of garbage by the quarter- master's department, systematic inspection of quarters and grounds, and systematic bathing and cleansing of clothing, characterize the perfectly adjusted sanitation of a permanent camp. Every large army camp has its remount camp and company stables. The farther these stables arc located from the soldiers' barracks the better will be the fly conditions in the living quarters of the men. The actively engaged army, however, presents entirely different con- ditions. There is no possibility of developing sewage systems, but tem- porary latrines must be substituted (see figs. 4, 5, 6, 7). Manure and garbage cannot be farmed out to contractors, but must be disposed of 46 SANITARY ENTOMOLOGY 'V^--*Xi-'«- mtfal Uf Fig. 1. — Cross section of Mann's hillside incinerator, used at U. S, Marine Camp, Quantico, Va. (Mann). Ho£iv«a y iK^lhodf bstfolh earth »ftpCt Fig. 2. — Modification of Mann's hillside incinerator, adapting it to level ground (Mann). NliaitbM nuKtkstt ^tneodUt CMtsUr* wiTn ptrforAttd rtrtorAita Fig. 3. — Small incinerator of the Ferguson type, for use of small units, and capable of transportation (Mann). SERIOUSNESS OF INSECT-BORNE DISEASES TO ARMIES 47 --~:^^^'i^- -^^^ ^^^^ Fig. 4. — Straddle trench latrines, 1 foot wide, 2 feet deep, 3 feet long, for field opera- tions at temporary locations (Mann). Fio. 5. — Covered pit latrine level with ground, a semi-permanent type (Mann). Fio. 6. — Garbage can with top converted into portable urinal for use in company street at night (Mann). 48 SANITARY ENTOMOLOGY by hastily built incinerators, or the manure stacked and treated to kill flies. Ditches and standing water cannot be drained. They must be treated to kill insect life in them. Temporary hospitals abound and must be protected from flies and vermin. The men sleep out of doors or in scanty shelters, even in pig pens, barns, etc., wherever they can find shelter in inclement weather. Insect infestation in these must be reduced to a minimum. When lice abound, hastily constructed devices must be installed or the clothing treated by chemicals. The trenches and dugouts have to be sprayed with creosote oils to keep away flies and kill vermin. Terrible stenches arise from dead bodies and these must be buried or treated to prevent fly breeding. In other words, everything here must be done hastily but Fig. 7. — Urine soakage pit, in cross section (Mann's modification from Lelean). effectively, for tomorrow the work may have to be done all over some- where beyond or behind. The larger the body of men assembled and the greater the carnage, the more serious the diseases of all kinds and especially those carried by insects. In the great European War the greatest diseases were those borne by lice. In fact there is plenty of evidence that louse-borne diseases have been among the worst in many wars of the past. Three serious diseases which ravaged the trenches are carried only by lice, — typhus fever, trench fever, and European relapsing fever. INIillions of the Serbian nation were wiped out by typhus fever. The Roumanian nation was swept by typhus and relapsing fever. Russia, Germany, Austria and France suff'ered terribly from these louse-borne diseases. Trench fever spread back from the trenches into the cities. And yet all of these diseases can be controlled absolutely by suppressing the lice. It is easy to see how serious it is if a case of any of these diseases enters the SERIOUSNESS OF INSECT-BORNE DISEASES TO ARMIES 49 trenches. The lice spread from man to man, and they are noted for leaving a man with feverish conditions for a normal man. Another disease which has been especially bothersome in the trenches is scabies. Both horses and men are seriously afflicted with this mite disease, and special veterinary hospitals were constructed in France solely for handling horse scabies. In malarious countries where mosquitoes are breeding in great num- bers, malaria is a very serious camp and army problem. Campaigns in tropical countries are endangered often by yellow fever, dengue and filariasis, which are also mosquito-borne diseases. The troops engaged in Asia and some parts of the Mediterranean lit- toral had to contend with the possibilities of plague outbreaks. Troops engaged in the African campaigns had to deal with trypanosome and spirochete diseases. Along the Mediterranean littoral pappataci fever is to be seriously considered. For example, a detachment of the British Army in Egypt was suddenly attacked by an outbreak of this disease. We are all familiar with the disaster of our Spanish-American War in which so many thousands were carried away by typhoid fever, dysen- tery and diarrhea, all fly-borne diseases. In the present war, to these must be added Asiatic cholera, also borne by the fly. The great quantity of carcasses on the battlefield gives rise to myriads of flesh and carrion flies and as a consequence of the habit of these flies of attacking wounds of living people, there were many cases of human as well as animal anthrax in the European War. These are only the more important army diseases carried by insects. One of the greatest dangers to troops in active service lies in their moving into countries with obscure or little studied diseases, or diseases against which the men have had no chance to develop immunity. CHAPTER V Relation of Insects to the Parasitic Worms of Vertebrates * B. H. Ransom The only important part insects are known to play in the propagation of parasitic worms that affect human beings and other vertebrates is that of true intermediate hosts necessary to the existence of the parasites in some of their stages of development. Observations have been recorded in the literature showing that flies and other insects may swallow the eggs of various parasites of man such as hookworms, whipworms and other nematodes in whose life history no intermediate hosts are required, also the eggs of tapeworms in whose normal life history it is known that insects are not concerned, for example, Taenia saginata, whose inter- mediate host is the ox. It has been supposed that insects may thus act as mechanical carriers for such parasites, but as a matter of fact definite •evidence of the importance of insects as mechanical carriers of the eggs or larvae of parasitic worms has not yet been brought forth. On the contrary there are reasons to suppose that in some cases at least the swallowing of the eggs or larvae of parasites by insects that can act only as mechanical carriers and not as intermediate hosts, reduces rather than increases the chances of the young parasites continuing their development and reaching a host in which they can become mature. Among the parasitic worms affecting man and other vertebrates it is those forms requiring intermediate hosts, so-called heteroxenous parasites, that are of special interest so far as insect transmission is concerned. The monoxenous parasites, or those requiring no intermediate host, may practically be left out of consideration, with the admission that the mechanical carriage of monoxenous parasitic worms by insects may in the future be proved to have an importance not yet demonstrated. A complete demonstration of the part played by an insect in the life history of a given species of parasite is often a difficult matter. The animal which serves as the final host may be subject to infection not only with the species of parasite under investigation but also with other species liable to be confused with it in some of its stages. The insect *This lecture was read to the class on December 16, 1918, and distributed January, 1919. It has been revised up to date. The names of insects have been revised by the editor. 50 RELATION OF INSECTS TO THE PARASITIC WORMS 51 may likewise harbor parasites other than the one that is being studied. The possibilities of confusion and of the entrance of extraneous factors into the problem are so many and so varied that in most cases it is only after the most rigorously controlled experiments, combined with careful comparative studies of the successive stages of the parasite, that conclusions may safely be drawn. Furthermore, in working out the life history of a parasitic worm it is not sufficient to prove that insects of a certain species can act as intermediate hosts under experimental condi- tions. Some species of parasitic worms are able to develop in more than one species of insect, and the fact that a certain parasite can develop in a certain insect does not necessarily mean that under natural conditions the species of insect in question serves as the intermediate host of the parasite. For example, one of the common parasites of sheep and cattle is able to pass through its larval stages in cockroaches. These insects become readily infected if the eggs of the parasite which occur in the feces of the final host animals are fed to them. Under natural conditions, however, cockroaches do not ingest the feces of sheep and cattle, nor are they found in places where they are likel}^ to be picked up by sheep and cattle. Besides cockroaches, various species of dung beetles have been shown to be capable of acting as intermediate hosts of the parasite in question, and it is evident that these insects are the natural intermediate hosts. Unlike cockroaches they have plenty of opportunity both of becoming infected and of passing on their infection to the final hosts. A more or less intimate environmental relationship between the insect host and the final host generally exists in the case of parasites transmitted by insects. In a number of cases the insects are coprophagous and also likely to be ingested by the final hosts, as in the instance just cited. Another highly interesting group of cases is that in which the insects are ectoparasites on the final hosts, or bloodsuckers that periodically visit tliem, and thus have particularly favorable opportunities for becom- ing infected with parasitic worms harbored by the animals they attack and in turn reinfecting the latter. MODE OF INFECTION OF INSECT HOSTS As already stated the part which insects may take in the propagation of parasitic worms of higher animals is that of intermediate hosts, in which certain larval stages of the parasites are passed before they are ready to enter the bodies of their final or definitive hosts in which they develop to maturity. The way in which the insects become infected varies with different species of parasites. In the case of some species which live in the alimentary tract of the final host the eggs or larvae are dis- charged from the body of the host in the feces. Coprophagous insects 52 SANITARY ENTOMOLOGY swallow the eggs and if the}- are suitable intermediate hosts for the parasites the young worms go through several developmental stages and finally within the bodies of the insects reach a stage in which they are ready to be introduced into the body of the final host. Certain parasites whose adult stages live in relation with the blood vessels of the final host discharge their young into the blood stream whence they may be ingested by bloodsucking insects in whose bodies they undergo development to a stage infective for the final host. Aquatic insects may swallow free-living larval stages of parasites, or may be actively attacked by larval para- sites which gain entrance to their bodies by penetrating the cuticle. These insects may in turn be eaten by other insects and the infection thus passed on to them. In some cases the parasites may be taken up by insects or enter their bodies during an early stage of development of the insects and persist in later stages. Infection may thus occur during one stage of the insect but the development of the parasite to a stage infective for the final host may not be completed until after the insect has reached a later stage. Thus flies become infected with a certain parasite of the horse during the maggot stage, but the young parasites do not become suffi- ciently developed to be returned to the final host until the flies have reached the pupal or adult stage. MODE OF INFECTION OF VERTEBRATE HOSTS Parasitic worms that have insects for intermediate hosts reacli their final hosts in various ways. In the case of some species the insect hosts are swallowed either as the habitual food of the final hosts, or incidentally with food or drink. In other instances the young worm may have already escaped from its insect host before it is taken in with food or drink by its final host. The cases of accidental infection with horse- hair worms not normally parasites of human beings are likely to have happened in this way. The parasites of which bloodsucking insects are intermediate hosts may be introduced into their final hosts as a result of the escape of the larval parasites from the insects at a time when the insects are drawing blood. Commonly the larvae burst through a weak spot in the cuticle of the insect and then burrow into the skin of the final host. SPECIES OF WORMS FOUND IN INSECTS The parasitic worms of the higher animals in whose life history insects and insect-like organisms play a part, belong to two large zoological groups, Plathelminthes and Nematliclminthes. The former may be sub- divided so far as concerns parasitic forms into Cestoda, or tapeworms, RELATION OF INSECTS TO THE PARASITIC W0R:\I3 53 and Trematoda, or flukes ; the latter into Nematoda, or roundworms in the restricted sense, Gordiacea, or horse-hair worms, and Acanthocephala, or thorn-headed worms. CESTODA OR TAPEWORMS All tapeworms whose life history has been well established require an intermediate host, and are thus heteroxenous parasites. A typical life histor}' of a tapeworm is as follows: The adult lives in the intestine of the final host. The eggs pass out of the body of the infested animal in the feces. The feces or food or drink contaminated by them are swallowed by an animal that can act as an intermediate host. The eggs thus reaching the intermediate host hatch in the alimentary tract and the embryos set free migrate into nearby or remote tissues of the body, developing finally into an intermediate stage, commonly of the type known as a cysticercoid, in the case of those tapeworms whose intermediate stages occur in insects. Having reached this stage further development of the parasite awaits the time when the intermediate host or infested por- tions of its body are swallowed by an animal that can act as the final host, whereupon it resumes its development and, becoming mature, completes the life cycle. About 100 species of tapeworms are known whose adult stages occur in man or domestic animals. Four of these, Dipt/Udium caninum (the double-pored tapeworm of the dog, cat, and man), Hymen- olepis diminuta (the yellow-spotted tapeworm of rats, mice, and man), Hymenolepis nana (the dwarf tapeworm of rats, mice, and man), and Choanotcenia infundibidum (one of the tapeworms of the domestic fowl), have insects as intermediate hosts, with the possible exception of the dwarf tapeworm, in whose life history the part played by insects has not been definitely determined. Dipylidium caninum (Linnasus, 1758) llailliet, 1892 This tapeworm, sometimes called the double-pored dog tapeworm, is of very common occurrence in the small intestine of dogs and cats, and of occasional occurrence in human beings. Its larval stage (cysticercoid) occurs in the biting dog louse [Trichodectes latus (canis)^ as deter- mined experimentally by Melnikov (1869), and in fleas (Ctenocephalus canis, C. felis, and Pulex irritans). Fleas apparently are the usual intermediate hosts. Grassi and Rovelli (1888, 1889) followed the various stages of lam'al development in adult fleas, from the hexacanth embryo to the fully developed cysticercoid, and as they failed to find the parasite in larval fleas concluded that only adult fleas can act as hosts. Rccentl}', however, Joyeux (1916) has reached the conclusion that adult fleas 64 SANITARY ENTOMOLOGY are unable to swallow the eggs of the tapeworm. He finds that larval fleas readily swallow the eggs ; these hatch in the intestine of the insect, and the embryos thus released penetrate into the body cavity. They per- sist in the hexacanth stage until the transformation of the flea into the adult, after which they proceed with their development and in a short time reach the cysticercoid stage. Infection of the dog, cat, or human being occurs naturally as a result of swallowing infested fleas. Fleas are exposed to infection owing to the fact that their larvae live in an environment likely to be contaminated by the feces of infested dogs or cats. The eggs of the tapeworm as passed in the feces are grouped in capsules containing about a dozen eggs, so that infection of the insect host is likely to be multiple. The double-pored tapeworm is relatively uncommon in man and most of the cases recorded, of which there have been less than 100 all told, three in the United States, are among young children. Children are more likely than adult human beings to swallow fleas, which would explain the greater frequency of infestation among children. Another possible explanation of the more common occurrence of this parasite among children than among adults is that older persons may possess a greater immunity to infection. Prophylaxis against the double-pored tapeworm consists chiefly in keeping dogs and cats free from lice and fleas, and so far as human beings arc concerned excluding dogs and cats, especially if they are lousy or infested with fleas, from human habitations. Hymenolepis diminuta (Rudolphi, 1819) Blanchard, 1891 Hymenolepis diminuia (the yellow-spotted tapeworm) is of frequent occurrence in the small intestine of rats and mice, particularly the former, and of occasional occurrence in the intestine of man. The adaptability of the adult tapeworm to hosts so widely different as rodents and human beings is paralleled by the adaptability of the larval stage to various intermediate hosts. Cysticercoids belonging to this species have been recorded in various insects, a Lepidopteron, Asopia farinalis, in both larva and imago; a Dermapteron, Anisolabis anmdipes; Coleoptera, AJiis spinosa, Scatirus striatus, and Tenebrio molitor; and fleas CeratophyUus fasciatus, Xenopsylla cheopis, Pulex irritans, and Ctenoceplialus canis; also in myriapods, Fontaria virginiensis and Juhis sp. Nicoll and Minchin (1911) found the cysticercoids in about 4 per cent of the rat fleas (8 out of 207) they examined during a period of thirteen months, and they succeeded in infecting rats with the tapeworm by feeding them fleas, as Grassi and Rovelli (1892) had previously done by feeding other insects. Joj^eux (1916) infected the larvae of Asopia farinalis by feeding the eggs of H. diminuta and believes the cysticercoids recorded in the RELATION OF INSECTS TO THE PARASITIC WORMS 55 adult moth by Grassi and Rovelli were carried over from the larval stage of the insect. He failed in his attempts to infect Forficula auricidaria, Blatta orientaUs, and Blattella germanica. He also failed to infect beetles belonging to the species Blaps viortisaga, but succeeded easily in infecting the adults of Ten'ebrio molitor. The larvae of this latter beetle according to Jo^^eux are incapable of acting as intermediate hosts of H. diminuta. He was able to infect the larva? of rat fleas and of Pulex irritans and Cfenocephalus canis. In these insects the embr3'os of //. dinmiuta begin immediately to develop into cysticercoids and do not wait for the transformation of the larval fleas into adults, as Joyeux found in the case of Dipylidium caninum, the embryos of which apparently lie dormant in the insect until after it transforms into the adult stage. In this country Nickerson (1911) has reared the cysticercoid in myriapods, Fonfaria virginiensis and Jidus sp., fed on the eggs of the tapeworm. He failed in his attempts to infect meal worms. It is evident that infection of the definitive host with H. diminuta results from swallowing infested insects, the latter having become infested as a result of swallowing the eggs contained in the feces of animals harbor- ing the tapeworms. As a parasite of man in the United States, so far as available statistics show, H. diminuta ranks about third in frequency among the tapeworms, the beef tapeworm (Tcenia saginata) being the most common, and the dwarf tapeworm (H. nana) being next. Evident prophylactic measures are those directed toward the destruction of rats and mice and the avoidance of the ingestion by human beings of the various insects that may serve as intermediate hosts, especially the pro- tection of farinaceous foods from insect infestation. Hymenolepis nana (Siebold, 1852) Blanchard, 1891 Hymenolepis nana (the dwarf tapeworm) is a very common intestinal parasite of rats and mice and is of rather frequent occurrence in man, especially in children. In the United States it ranks second to the beef tapeworm in the order of frequency among the tapeworms of man. Its life history has not been fully worked out. Grassi (1887), however, has found that cysticercoids develop in the intestinal villi of rats that have been fed the eggs of the dwarf tapeworm. According to his view the cysticercoids later break out of the villi into the lumen of the intes- tine and grow into mature tapeworms. The rat thus acts both as inter- mediate and definitive host of the dwarf tapeworm, the parasite being spread from one rat to another through the medium of the eggs passed in the feces. Tlie dwarf tapeworm, according to Grassi's version of the life cycle, is an exception to the rule among tapeworms that the adult stage occurs in one species of animal and the larval stage in another 56 SANITARY ENTOMOLOGY species likely to be eaten by animals of the species that harbors the adult tapeMorm. Inasmuch as Nicoll and Minchin (1911) have found cysticercoids in a rat flea (Ceratophyllus fasciatus) that in details of liead structure are apparently exactly similar to and specifically identical with the dwarf tapeworm, the question arises whether such insects may not act as inter- mediate hosts, and whether in addition to the life cycle of an exceptional type described by Grassi, the dwarf tapeworm also has a life cycle of the ordinary type. T. H. Johnston has found cysticercoids similar to those recorded by Nicoll and Minchin in another species of rat flea (Xenopsylla cheopis) as well as in Ceratophiillus fasciatus. Joyeux (1916) has failed in experiments with fleas belonging to the species named and to related species, to infect them with H. nana. He states he used both larval and adult fleas. On the other hand he was able to confirm Grassi's results and succeeded in infecting a large number of rats and mice by feeding them the eggs of the tapeworm. The experi- mental evidence thus far available accordingly favors the view that insects do not play a necessary" part in the life liistory of the dwarf tapeworm. Furthermore, considering the frequency of occurrence of H. nana as a parasite of man, and the enormous numbers of the parasites sometimes present, it would seem that infection is more likely to occur in the manner described by Grassi than as a result of swallowing rat fleas, there being of course a greater likelihood of human beings swallowing rat feces or fecal matter from other human beings containing large numbers of eggs of the tapeworm than of swallowing rat fleas containing a sufficient num- ber of cysticercoids to develop into the large number of tapeworms that have been found in some cases. Choanotcenia infundibulum (Bloch, 1779) Cohn, 1899 Choanotcenia infundibulum is a common tapeworm of chickens in various parts of the world. Grassi and Rovelli (1892) in Italy found cysticercoids in the common house fly (Musca domestical which on account of their morphological similarity to ChoanotcEnia infmulibulum they inferred belonged to this species. From the results of experiments conducted in this country by Guberlet (1916) it appears safe to conclude that the common house fly acts as the intermediate host of the tapeworm, Chocmotcenia infundibulum, infection of the fly apparently occurring as a result of swallowing the eggs of the tapeworm, and the chicken in turn acquiring the parasite as a result of swallowing flies infested with the cysticercoid stage. Whether infection of the fly regularly occurs during the larval or during the adult stage, or during both stages, has not been definitely settled. RELATION OF INSECTS TO THE PARASITIC WORMS 57 Prophylaxis in the case of this tapeworm is obviously largely dependent upon fly control measures. Other Tapeworms According to Villot (1883) the larval tapeworm observed by Stein (1852) in the larva of Tenebrio molitor belongs to the tapeworm of the mouse, known as Hymenolepis microstoma. The same writer (1878, 1883) also associates with certain tapewonns of shrews, two species of larval tapeworms which he found in myriapods, Glomeris limhata. Fur- ther investigations of these parasites appear necessary to substantiate the views held by Villot as to their specific identity. Ackert (1918, 1919) has recently recorded some experiments in which chickens were given house flies and became infested with tapeworms (Davainea cesticUlus and D. tetragona). The immature stages of these parasites were not, how- ever, seen in the flies and the possibility is not excluded that the chickens became infected from some source other than the flies, notwithstanding the precautions taken against extraneous infection. Guberlet (1919) caught stable flies (Stomoxys calcitrans) in poultry yards where the chickens were commonly infested with Hymenolepis carioca (Magalhaes, 1898) and fed them to young chicks with the result that some of them became infested with this tapeworm. He concludes that the stable fly possibl}' serves as an intermediate host of this tapeworm. TREMATODA OR FLUKES All species of flukes whose life history is known depend upon molluscs as hosts for certain larval stages, and they may or may not require one or more additional intermediate hosts before they reach the definitive host. It is as intermediate hosts following the first intermediate host, a mollusc, that insects can play a part in the propagation of flukes. As yet it has not been shown that insects are concerned in the life history of any of the flukes (about 100 known species) that aff*ect human beings or domestic animals, but as the life history of all of these parasites has not been determined it is quite likely that in the case of some species insects will be found to act as intermediate hosts. Different species and groups of species show various types of life history with reference to the number of larval stages through which the parasite passes and the number of intermediate hosts required. A comparatively simple life cycle is as follows : The mature fluke in the definitive host produces eggs which pass to the exterior in the feces. Under suitable conditions of moisture and temperature the Qgg hatches and a ciliated larva, the miracidium, issues. If this miracidium finds a suitable mollusc (diff'erent species of molluscs 58 SANITARY ENTOMOLOGY attract different species of miracidia) it burrows into the soft tissues of the mollusc and reaching the respiratory chamber proceeds to develop into the next stage, the sporocyst. Within the sporocyst by a process of internal budding more or less numerous so-called redice develop. The rediae finally leave the sporocyst and migrate into the liver of the mollusc. In the redia several generations of daughter rediae may develop by budding. The next stage, developed also by internal budding from the redia, is the cercaria. The cercaria of some species is provided with a tail by means of which it swims about in the water when it finally escapes from the mollusc. The cercaria may be swallowed by or actively pene- trate into some animal and become enc\'sted in this animal. Finall}' when the animal harboring encysted immature flukes is swallowed by an animal which can serve as a host of the adult fluke, the young flukes thus reach- ing their definitive host develop to maturity and the life cycle is complete. Following is given a partial list of the insects in which young flukes have been recorded. The species to which the young flukes in question have been assigned and the final host animals are also indicated. Further investigations are likely to show that some of the flukes from insects have been misidentified and do not belong to the species to which they have been supposed to belong, and the data given in the list should not be accepted as fully proved in any case, though there can be no doubt in some of the cases cited. No distinction has been made between certain and doubtful cases, except that a few that are doubtful are indicated by question marks. The determination of species of young flukes found in insects has generally been made solely upon their morphological similarity to adults occurring in vertebrate hosts and it is quite likely that mistakes have been made by investigators of these parasites just as mistakes have frequently been made in the association of immature and adult parasites belonging to other groups of worms. NEMATODA OR ROUNDWORMS Among parasitic worms the species of nematodes are more numerous than either the species of tapeworms or flukes. Nematodes as a group are not exclusively parasitic and thousands of free-living species are known to exist, although comparatively few have been described. Many species of nematodes are parasites of insects only and do not occur in other animals. Insects therefore harbor parasitic nematodes which belong to them exclusively as well as the larval stages of nematodes that occur in higher animals in their adult stage. The ubiquity of free-living nema- todes introduces a frequently troublesome complication into the study of the life histories of monoxenous parasitic nematodes of which there are many species, and the common occurrence of parasitic nematodes RELATION OF INSECTS TO THE LIFE CYCLE OF FLUKES Insect Host Adult Fluke. Final Host Coleoptera Ilybius fuliginosus (Fabricius) (adult) Haplometra cylindracea Fiogs Water beetle (larva) Prosotocus confusus Pleurogenes medians << " '* claviger ti Lepidoptera Nymphula nymphseata (Linnaeus) (larva") Unknown Unknown Diptera Anopheles maculipennis Meigen (claviger Fa- bricius) (adult) " " Anopheles rossi Giles (adult) " " Chironomus plumosus Linnteus (larva) Lecithodendrium ascidia Bats Culex quinquefasciatus Say (fatigans Wiede- mann) (adult) Unknown Unknown Trichoptera Anabolia nervosa (Leach) Curtis Allocreadium isoporum Cyprinoid fishes Anabolia nervosa (larva) Opisthioglyphe rastellus Frogs Chsetopteryx villosa (Fabricius) (larva) Allocreadium isoporum Cyprinoid fishes Drusus tri6dus McLachlan (larva) Unknown Unknown Limnophilus rhombicus (Linnaeus) (larva) Opisthioglyphe rastellus Frogs griseus (Linnaeus) (larva) " " " " lunatus (Curtis) (larva) " " " " flavicornis (Fabricius) (larva) " " " Mystacides nigra (Linnaeus) (larva) Unknown Unknown Notidobia ciliaris (Linnseus) (larva) " " Phryganea sp. Lecithodendrium chilostomum Bats Phryganea grandis (larva) Unknown T'nknown Rhyacophila nubila Zetterstedt (larva) ' Bats Neuroptera Sialis lutaria (Linnaeus) (larva) " Unknown Odonata ^schna (larva and adult) Prosotocus confusus Frogs Agrion (larva) Gorgodera pagenstecheri " varsoviensis Pleurogenes medians „ Calopteryx virgo (Linnaeus) Halipegus ovocaudatus " " " (larva and adult) Pneumonceces similis " Cordulia (larva) Prosotocus confusus " Epitheca " Gorgodera cygnoides " pagenstecheri " varsoviensis " Plectoptera Cloeon dipterum (Linnaeus) Stephens (larva) ? Opisthioglyphe rastellus " Ephemera vulgata Linnaeus (larva) Allocreadium isoporum Cyprinoid fishes >( <. « ? Opisthioglyphe rastellus I'Vogs Ephemeridae (larva) Lecithodendrium ascidia Bats Plecoptera Perlidae (larva) Lecithodendrium ascidia " Unknown Unknown 59 60 SANITARY ENTOMOLOGY among insects introduces an equally troublesome complication into the study of the life histories of the heteroxenous nematodes parasitic in higher animals, for which insects may serve as intermediate hosts. About 250 species of nematodes have been recorded as parasites of man and domestic animals. Many of these require no intermediate hosts, but some are heteroxenous parasites, and a number of these are known to have intermediate stages in insects and closely related arthropods. In the following discussion, in addition to the nematodes parasitic in man and domestic animals, certain species parasitic in other animals are also con- sidered because of the part played by insects in their life history. For convenience they may be placed in two groups, (1) those in which the eggs or first-stage larvae leave the body of the final host in the feces, and (2) those in which the first-stage larva? occur in the blood or lymph of the final host and leave the body through ingestion by bloodsucking insects. 1. Parasitic Nematodes Whose Eggs or Larvce Leave the Body of the Fviial Host in the Feces Protospirura muris (Gmelin, 1790) Seurat, 1915 This nematode, parasitic in its adult stage in the stomach of various species of rats and mice, is of special interest historically as being the first parasite in whose transmission to its final host an insect was found to be concerned. Stein in 1852 recorded the presence of encysted nema- todes in the larvfe of meal beetles (Tenehrio molitor). Leuckart (1867) and Marchi (1867) fed eggs of Protospirura muris (Spiropfera obtusa) to meal beetle larvae and followed the development of the young nematodes up to the encysted stage found by Stein. This development is completed in about six weeks after ingestion of the eggs. The development to the adult stage was also followed in mice fed with the encysted nematodes from meal worms. Johnston (1913) has recorded encysted nematode larvae which appeared to him identical with those of P. muris in the body cavity of a rat flea (Xenopsylla cheopis). Spirocerca sanguinolenta (Rudolphi, 1819) Railliet & Henry, 1911 The adults of this nematode live in tumors of the stomach and esophagus of the dog and the wolf. The eggs unhatched pass out of the body of the dog in the feces. Grassi (1888) found encysted iarval nem- atodes in cockroaches (Blatta orientalist which he suspected were the larvje of aS". sanguinolenta. Dogs fed with these encysted nematodes after five days showed the larva* free in the stomach ; after ten days the young worms were further developed and were firmly attached to the mucosa RELATION OF INSECTS TO THE PARASITIC WORMS 61 of the esophagus ; and after fifteen days they had sunk themselves into the wall of the esophagus and had developed still further. Grassi con- cluded that cockroaches act as intermediate hosts, swallowing the eggs in the feces of infested dogs, and'in turn being swallowed by dogs. Seurat (1913), however, believes that Grassi was mistaken as to the identit^^ of the encysted nematodes found in the cockroaches, and that they were really the laiTje of Sinrura gastrophila, the adult of wliich occurs in the stomach of the cat, hedgehog (Erinaceus algirus), and fox (Vvlpes vulpes atlantica). Seurat (1912, 1916) finds what he considers to be the larvae of S. sanguinolcnta encysted in a great variety of animals including beetles, reptiles, birds, and mammals. The presence of the encapsulated larvae in various vertebrates he explains as the result of the ingestion of insects infested with the larvae. If the vertebrate is not a host in which the parasites can continue their development as they would in their normal host the dog, they migrate into the wall of the alimentary tract or mesentery and become reencysted without further development. If, however, the infested insect is swallowed b^'^ a dog the larvae, after the}' have been freed by digestion of the cysts surrounding them, continue their development and finall}' reach maturity. Seurat in fact found that encysted larvjE in insects identified as those of S. sanguinolenta when fed to mice became reencysted in the manner described. Seurat (1916) records the following insects as hosts of the larvfe of S. sanguinolenta, all of them beetles: Scarabaus (Ateuchus) sacer,vScarabcEus (Ateuchetus) variolosus, Akis goryi, Geotrupes douei, Copris hispanus, and Gymno- pleurus sturmi. According to Seurat the life C3'cle of S. sanguinolenta would be as follows : The eggs pass out of ^nfested dogs in the feces, are ingested by beetles, hatch, and the larvae after a period of growth and development become encysted. If infested insects are swallowed by dogs or wolves the larval worms are released from their capsules and develop to maturity. If the insects are swallowed by other animals, the larvae may become freed frohi their cysts as in the alimentary tract of the dog, but they are unable to develop further and leave the lumen of the alimentary tract and become reencysted in the tissues to which they migrate. In such a case, of course, there is a possibility of their resuming their development if the infested animal should afterwards be devoured by a dog or a wolf, but this possibility apparently has not yet been sub- stantiated. Spirura gastrophila (Mueller, 1894) Marotel, 1912 This nematode in the adult stage occurs in the stomach and the lower end of the esophagus of the cat. It has also been recorded by Seurat (1913) from the stomach of a hedgehog (Erinaceus algirus) and the stomach and esophagus of a fox (Vulpes vulpes atlantica), and by the 62 SANITARY ENTOMOLOGY same author (1918) in the esophagus of the mongoose (Herpestes ichneumon). This author identifies certain encysted larval nematodes found in a species of Onthophagus, in Blatta orienfalis, in BJaps strauchi, and in Blaps sp. (near appendiculata) as belonging to S. gastrophila. He thinks the parasites found in the cockroach and called Filaria ryti- pleurites by Deslongchamps (1824), and those identified as such by Galeb (1878) who associated them with an insuflSciently described adult nematode of the rat, are probably the same as those he identified as the larvae of aS'. gastrophila. He also dismisses Grassi's experiments as insuffi- cient to show that the nematodes encysted in cockroaches are the larvae of Spirocerca sanguinolenta as Grassi believed, and concludes that Grassi was mistaken and was really dealing with the larvas of Spirura gastrophila. Seurat (1919) adds Ahis goryi to the list of insect hosts of the larvae of S. gastrophila. Gongylonema scutatuni (Mueller, 1869) Railliet, 1892 This nematode in the adult stage is a common parasite in the mucous membrane of the esophagus of cattle, sheep, and other ruminants, and has also been recorded from the horse. Ransom and Hall (1915, 1916, 1917) have shown that various species of dung beetles (Aphodius femoralis, A. granarius, A. fimetarius, A. coloradensis, A. vittatus, Onthophagus hecate, and O. pennsylvanicus ) act as intermediate hosts. Experimentally, cockroaches (Blattella germanica) can also be made to serve as intermediate hosts, a part of course which they do not play under natural conditions. The eggs of the parasite pass out of the body of the definitive host in the feces and are swallowed by dung beetles. They hatch in these insects, and the larvae entering the body cavit>^ undergo a certain growth and development, reaching their infective stage in about a month, meanwhile becoming enveloped in capsules in which they lie in a coiled-up position. Further development waits upon the swallowing of the infested inseet by a cow, sheep, or other suitable host as may readily occur while the animal is grazing, the insect being ingested with the herb- age upon which it happens to be. Following their ingestion by the defini- tive host, the larva? are released from their capsules and develop to matur- ity. Seurat (1916) has described some larval nematodes from the abdom- inal cavity of Blaps strauchi, Blaps appendiculata, and Blaps sp. (near appendiculata) in Algeria that he identifies as Gongylonema scutatum. As pointed out by Ransom and Hall (1917), however, these evidenth' belong to another species as they do not correspond to the forms shown by these writers to be the larvae of G. scutatuni. Seurat (1919) adds Blaps emondi to the list of insects in which he has found the larvse in question. RELATION OF INSECTS TO THE PARASITIC WORMS 63 Gongylonema mucronatum Seurat, 1916 This nematode occurs in the adult stage in the mucosa of the esophagus of the Algerian hedgehog (Erinaceus algirus). According to Seurat (1916) its larval stage is found encapsuled in the body cavity of various species of coprophagous beetles, Afeuchus sacer, Chironitis irroratus, Onthophagus bedeli, Gynmopleurus mopsus, Gymnopleurus stiirmi, and Geoti'upes clonal, but there appears to have been some confusion as to the identity of the larvse in question, and further investigation of the life history of this species is desirable (Ransom and Hall, 1917). Gongylonema brevispiculum Seurat, 1914 Seurat (1916), in addition to forms found in different species of Blaps that he considers to be third stage larvre of Gongylonema scutatum, has described as second stage larvae of G. scutatum some larval nematodes found encj'sted in the abdominal cavity of Blaps sp. and Blaps strauchi in certain localities in Algeria. In a later paper, however (1919), he has expressed the opinion, based upon the morphology of the worms and a knoAvledge of the mammalian fauna in the region in which the parasites are found, that these larvae are third stage larvse and belong to the species G. brevispiculum the adult of which occurs parasitic in the cardiac portion of the stomach of a species of jerboa (Dipodillus campestris). Further investigation seems desirable as to the identity of the supposed larvae of Gongylonema brevispiculum as well as of the other larvae of Gongylonema that have been assigned to various species on a basis of apparent morphological similarities and general considerations. A con- tinuation of the excellent work already done by Seurat relating to the larval forms of Gongylonema will no doubt clear up the confusion that now exists. Gongylonema neoplasticum (Fibiger and Ditlevsen, 1914) Ransom and Hall, 1916 This nematode occurs in the adult stage in the mucosa of the stomach, esophagus and mouth of the rat. It has been reared experimentally in the rabbit and guinea pig as well as in the rat and mouse. It is of special interest from the medical standpoint because it is commonly associated with and perhaps stands in etiological relationship to gastric carcinoma of rats. Fibiger and Ditlevsen (1914) have proved tiiat cock- roaches (Periplaneta americana, Blatta orientalis, and Blattclla german- ica), and a grain beetle (Tenebrio molitor) can act as intermediate hosts. The eggs are passed in the feces of infested rats and if ingested b}' one 64 SANITARY ENTOMOLOGY of the insects named will hatch, the larvae within twenty days after ingestion of the eggs developing to tlie infective stage. In this stage the larvjE arc coiled up in cysts in the muscles of the prothorax and legs, differing in location from the larvje of G. scutatum which in artificially infected cockroaches, as in their normal hosts, dung beetles, are found encysted in the body cavity. Arduenna strongylina (Rudolphi, 1819) Railliet and Henry, 1911 This nematode in its adult stage occurs in the stomach of the pig. Seurat (1916) has recorded the presence of larval nematodes in the stomach of a pig associated with adults of A. strongylina which he con- siders belong to this species. He has found morphologically similar lai-val nematodes encapsuled in the body cavity of Aphodius rwfus castaneus and states that they also occur in beetles of the genus Onthophagus. Ap- parently no feeding experiments have been carried out. Presumably the life history would be similar to that of Gongylonema scutatum, Proto- spirura muris, etc., that is, the eggs of the parasite passed in the feces are swallowed by beetles, the larvae develop in these insects to the infective stage, and are transferred to the definitive host when the beetles are swallowed by a pig, after which the young worms complete their develop- ment to maturity. Seurat (1919) records the presence of encysted larv;e of A. strongylma in the stomach wall of the Algerian hedgehog (Erinaceus algirus). Apparently, therefore, the larvae of this species that occur encysted in insects, like those of Physocephalus sexalatus and Spirocerca sanguinolenta, if ingested by vertebrates other than the normal hosts of the adult worms, migrate out of the lumen of the digestive tract and become reencysted in the neighboring tissues. Physocephalus sexalatus (Molin, 1860) Diesing, 1861 The adults of this nematode live in the stomach of the pig, dromedary, and donkey. Seurat (1913) has found two successive larval stages pre- ceding the adult in the stomach of the definitive host (donkey) and has also (1916) established the common occurrence of the earlier of these two stages in various dung beetles (Scarahceus YAteuchus^^ sacer, S. [Ateuchetus^^ variolosus, Geotrupes dou£i, Onthophagus nebulosus and O. hedeli). Pigs of course are commonly known to be coprophagus in their feeding habits and Seurat states that the donkeys of Algeria, where his investigations were made, commonly devour fecal matter swarming with dung beetles. The way in which the larvje of P. sexalatus reach their final host is therefore evidently through the ingestion of infested beetles by pigs, donkeys, or dromedaries. Presumably of course the beetles be- RELATION OF INSECTS TO THE PARASITIC WORMS 65 come infested by eating the eggs of the parasite which are passed in the feces of infested pigs, donkeys, and dromedaries. As in the case of Spirocerca sangninolcnta Scurat finds encysted Lirvc-e of P. sexalatus in various vertebrates in Algeria, particularly reptiles and insectivores. Their presence in these animals he would explain in the same way as he explains the presence of the encysted larvae of S. sangukwlenfa in such animals, that is, the larva? present in insects devoured by the animals in question are unable to continue their development as they would in pigs and other suitable hosts. On the other hand they do not succumb in their strange environment nor do they pass through the alimentary tract with the feces but penetrate into the walls of the stomach and into other tissues and become reencysted, surviving in this condition more or less indefinitely. They may thus be considered parasites that have gone astray but still capable of existence in their abnormal environment. The possibility of their developing to maturity after reencystment in a strange host if this animal should be eaten by a pig has not been substantiated experimentally. Seurat (1916) has counted 4,880 larvae identified as P. sexalatus in a single beetle, Scarahaus (AteucJms) sacer. In addition there were 68 larvae of Spirocerca sanguinolenta in the same beetle, making a total of 4,948 larvae in the one insect. Hahronema muscoe (Carter, 1861) Dicsing, 1861 This nematode in the adult stage occurs in the stomach of horses and other equines, commonly in association with another closely related species, H. microstoma. The life history of H. musca has been shown to be as follows (Ransom, 1911, 1913; Hill, 1918; Bull, 1919): The eggs or the larvae pass out of the body of the host in the feces. They enter the bodies of the larvae of the common house fly, probably being swallowed, though the mode of entrance has not been determined by direct observa- tion. The worm larvs grow and develop in the developing flies and at about the time the adult insects emerge from the pupal stage the larvae reach the infective stage. In this stage they are most commonly found in the proboscis. The ingestion by horses of flies harboring the larva^ brings the young parasites into the location where the adult occurs, and presumably this is the common method by which the larv;e reach their final host. The frequent swallowing of flies by horses is an undoubted fact. The mouths of horses are very attractiA^e to house flies especially while the horses are eating, as any one can determine by a few minutes' observat:4on of the animals during the fly season. There is also another possible and very probable way in which the larva? are transferred to horses, suggested of course by the habit of the larv.T of congregating in the proboscis of the fl}'. We may expect that it will be demonstrated 66 SANITARY ENTOMOLOGY in analogy with what has been shown to occur in Filaria transmission by mosquitoes, that the larva? of H: muscce can actively leave the proboscis of the fl}' while the insect is sucking moisture from the mouth or lips of the horse. There is already indirect evidence that this does occur. The researches of Descazeaux (1915), Bull (1916), and Van Saceghem (1917) have sliown tliat the nematodes which occur in cutaneous granulo- mata and so-called summer sores of horses are morphologically similar to the larvae of Hahronema musca and in all probability*belong to this or a closely related species. Recently Van Saceghem (1918) from investi- gations carried out in Africa has reached the conclusion that the nematode of summer sores is Hahronema muscce and that it is introduced by flies. Larvae from infested flies were placed in the eye of a horse kept in an insect-proof enclosure, with the result that conjunctivitis and verminous nodules of the nictitating membrane developed. In another experiment two wounds were made on the skin of a horse, one protected against flies and the other left uncovered. The horse was placed in a stable in which 20 per cent of the flies were infested with Hahronema. The unprotected wound became transformed into a typical summer sore. Bull (1919), who has made an extended study of cutaneous granulomata of horses in Australia, believes that the larvae of Hahronema megastoma are more often responsible for the production of habronemic granulomata than either H. musca or H. microstoma. Whether the Hahronema larvje in summer sores are able to migrate ultimately to the stomach and complete their development to maturity remains to be determined. Bull (1919) thinks it unlikely that the larv:B of Hahronema are able to reach the alimentary canal from the submucosa of the external mucous membranes or from the subcutaneous tissues, and Hill (1918) also notes that the evidence of the occurrence of such a migration is quite insufficient. It is of interest to note that Hahronema musca; was kno^vn as a parasite of the fly long before its relation to the horse was demonstrated. Carter in 1861 was the first to record the presence of the nematodes in flies, following which they were frequently observed by entomologists and others who had occasion to examine the proboscis of the fly under the microscope. Larval nematodes very similar to H. muscat have been seen in the proboscis of Stomoxys calcitrans by Johnston and others. The researches of Hill (1918) and Bull (1919) have shown that as far as their experience has gone the larvas in this species of fly have invariabW been Hahronema microstoma so that the occurrence of H. muscce in S. calcitrans appears questionable. The fact that these more or less injurious parasites of the horse depend upon flies for their existence is a point which may be added to RELATION OF INSECTS TO THE PARASITIC WORMS 67 those commonly used in arguments for the necessity of fly eradication. The possibility is also not excluded that flies may introduce Habronema larvae into human beings, in whose tissues they may perhaps Le able to live for a time and do considerable damage. Though there is no evidence that this ever occurs, the possibility is one that deserves consideration from those who have opportunity to investigate the relation of flies to wounds and other lesions of the skin and mucous membranes. Habronema microstoma (Schneider, 1866) Ransom, 1911 Hill (1918) and Bull (1919) have shown that Habronema microstoma, which, like H. musca, occurs in the adult stage in the stomach of the horse and other equines, has a life history similar to that of H. muscce. Both of these writers have occasionally observed the presence of H. microstoma in Musca domestica under experimental conditions but find that the usual intermediate host is Stomoxys calcitrans. As they repeatedly failed to infect S. calcitrans with the larvje of H. muscce it is probable that the forms from S. calcitrans reported by Johnston (1912) and othe-rs as H. muscce were H. microstoma. Bull (1919) is of the opinion that the larvse of H. microstoma may sometimes be concerned in the production of cutaneous granulomata of horses and that presumably they are introduced into the skin by the proboscis of an infested fly. Habronema megastoma (Rudolphi, 1819) Seurat, 1914 Hahronema megastoma in its adult stage occurs in tumors in the stomach of horses and other equines. Hill (1918) and Bull (1919) have found that its life history is similar to that of H. muscce, the house fly (Musca domestica) acting as intermediate host in both cases. Attempts to infect Stomoxys calcitrans with this species failed. Bull (1919) be- lieves that the larvae of H. megastoma introduced by infested flies are the usual cause of habronemic granuloma of horses. So far as the normal life history of H. megastoma is concerned he thinks that the presence of tlie larva* in the skin or mucous membranes of horses is to be considered accidental and that it is unlikely that they can reach the alimentary tract from such locations and become mature. According to his view, there- fore, which is shared by Hill (1918), H. megastoma and also the other species of Habronema reach the stomach of the horse as a result of the animal's swallowing infested flies. Acuaria spiralis (Molin, 1858) Railliet, Henry and Sisoff, 1912 The adults of this nematode have been recorded as parasitic in the esophagus and stomach of the domestic fowl. Insects have not been 68 SANITARY ENTOMOLOGY shown to act as intermediate hosts, but insect-like animals commonly known as sow-bugs apparently act as intermediate hosts, Piana (1897) having found larval nematodes in an isopod (Porcellio IcevisJ that corre- sponded in morphology with immature nematodes found in chickens harboring also the adult worms. Furthermore these larval nematodes occurred in sow-bugs only in the locality where the chickens were found to be infested. Although Piana identified the parasites that he found in chickens as Dispharagus nasutus (Rudolphi), it is apparent from his description and figures that they belonged to the species Acuaria spiralis (Molin). FUaria gallvnarum Theiler, 1919 Theiler (1919) has recorded the occurrence of larval nematodes in a species of termite (Hodotermes pretoriensis). Among the termites only the workers were found to harbor these parasites, no infested soldiers having been discovered. Infested termites can easily be distinguished by the swollen abdomen which gives thfe insect a sort of balloon-like appearance. According to Theiler, on many South African farms the custom exists of digging up nests of termites and allowing the chickens to feed on the insects, and the droppings of chickens running in the fields are naturally scattered about and serve as food for the termites. Infested termites were fed to young chickens that had been hatched in an incubator. Adult worms that had evidently developed from the larva? parasitic in the termites were found in the intestine or stomach in 15 out of 16 chickens that had been thus fed, but none were found in control chickens. The proper generic position of this nematode described by Theiler as a Filaria remains to be determined. Ascaris lumbricoides Linnaeus, 1758 This common parasite of man has been definitely shown to have a direct life history without intermediate host. The opinion of Linstow (1886) that a species of Julus (guttulatus) acts as the intermediate host is without foundation. The common house fl}^ may swallow eggs of this parasito as well as those of various other parasites which occur in the feces of infested human beings. The eggs pass through the intestine of the fly unhatched. Flies may thus scatter the eggs of Ascaris but there is no evidence that mechanical carriage of the eggs in this way assists materially in the spread of the parasite. There are various other natural agencies more effective than insects in spreading infection with parasites such as Ascaris. Stiles, however (according to Nuttall, 1899), fed females of Ascaris lumbricoides containing eggs to fly larvas (Musca domestica) and afterwards found the eggs in later stages of development RELATION OF INSECTS TO THE PARASITIC WORMS 69 in the pupae and adult flics that developed from the larvae. This sug- gested the possibility that flies having become infested as larvas might convey the parasite to man by falling into or depositing their excreta on food. Apparently these experiments have not been repeated. 2. Parasitic Nematodes Whose First-stage Larvae Occur in the Blood or Lymph of the Final Host and Leave the Body Through Ingestion hy Bloodsucking Insects Filaria bancrofti Cobbold, 1877 This important parasite of man is widely distributed throughout the world in tropical and subtropical countries. It occurs in the United States, thougii apparently it is by no means common. Historically it is of special interest because of the fact that it is the species which Manson (1878) showed passed through certain metamorphoses in the bodies of mosquitoes after the larvse had been sucked up by these insects in the blood of human beings affected with filariasis. Manson's researches coupled with confirmatory work by other investigators established the novel fact of the transmission of an animal parasite by a bloodsucking insect, and may be taken as the starting point in the development of our knowledge concerning the part played by such insects in the spread of disease-causing organisms. Lewis had also observed the passage of the larvas from the human host into mosquitoes. The first obsei'vation of these larva? in man was recorded by Demarquay in 1864 in Paris, the adult female was discovered by Bancroft in 1876 in Queensland, and the adult male by Bourne in 1888. The adults of this species live in the lymphatic system, both vessels and glands. The first-stage larvae which are provided with a thin cutic- ular sheath, apparently the transformed egg shell, are found in the blood stream, usually periodically as first shown by Manson, that is, in consid- erable numbers only at night or rather during the hours of sleep, as the periodicity may be reversed by making the patient sleep during the day time. One of the names of the parasite, Filaria noctuma, is based upon the periodicity of the appearance of the larvae in the blood. Various pathological conditions have been attributed to Filaria bancrofti such as adenitis, lymphangitis, abscesses, lymph scrotum, chyluria, and other disturbances of the lymphatic system. The connection between filariasis and elephantiasis is still a matter of argument among pathologists. When taken into the stomach of a mosquito the larvas lose their cutic- ular sheaths. Within 24 hours they leave the alimentary tract, pass into the body cavity, then into the muscles of the thorax. In the muscles they become shortened to about half their original length and meanwhile 70 SANITARY ENTOMOLOGY increase to twice or more than twice their original thickness, developing into what is known as the sausage stage of general occurrence in the development of Filaria larva?. Developing beyond this stage they increase rapidly in length, cast their skins at least once, and in one to two weeks after infection of the mosquito, or longer, according to temperature and the species of mosquito infected, they complete their larval development so far as the intermediate host is concerned, reaching a length finally about three to five times the length of the first-stage larva? and a thickness about three or four times the original thickness. They leave the muscles, enter the body cavity, and migrate into various locations, posterior por- tions of the body, legs, palpi, but in greatest numbers into the labium. From the evidence afforded by the experiments of Noe (1900) with Dirofilaria immitis and additional experiments by Bancroft (1901), Lebredo (1904-1905), Fiilleborn (1908), and others, it has been con- cluded by analogy in the case of Filaria bancroffi that when an infected mosquito bites a human being the filaria larvae bore through a thin portion of the labium known as Dutton's membrane, and more rarely other thin portions of the proboscis, actively penetrate the skin of the individual attacked, and reach the lymphatic system where they complete their development to maturity. Both anopheline and culicine mosquitoes can serve as intermediate hosts of Filaria bancrofti including the following species (see also Chapter XVII) : Anopheline mosquitoes Anopheles (Myzomyia) rossi Giles. " (Pyretophorus) costalis Loew. " {Myzorhynchiis) sinensis Wiedemann. " " " peditcpniatus Leicester. " ** barbirostris Van der Wulp. Culicine mosquitoes Culex pipiens Linnaeus Aedes argenteus Poirret {Stego- myia calopus Meigen) " quinquefasciatus Say {fati- Aedes gracilis Leicester (Stego- gans Wiedemann) myia) Aedes scutellaris Walker {Culex " gelidus Theobald albopictus Skuse) " sitiens Wiedemann Mansonioides uniformis Theobald Mansonioides annulipes Theobald Scutomyia albolineata Theobald Taeniorhynchus domesticus Lei- cester RELATION OF INSECTS TO THE PARASITIC WORMS 71 Besides those named about a dozen other species of mosquitoes have been tested as hosts of Filaria bancrofti with negative results, or with results showing that the parasites would only develop imperfectly. Fleas, lice, and Stomoxys have been tested with negative results. Prophylaxis against Filaria bancrofti evidently consists in measures similar to those employed in malaria eradication with reference to mos- quito control. Filaria (Loa) loa (Cobbold, 1864) This parasite of man is a West African species. It has been brought to America in the slave trade but never established in the New World. The adults live usually in the subcutaneous connective tissue but have been found elsewhere in relation with the serous membranes of the ab- dominal and thoracic viscera. They move about from place to place and can change their location rather rapidly ; for example, one of these worms has been seen to cross the bridge of the nose beneath the skin within a period of an hour or two. In their progress beneath the skin in various parts of the body they give rise to transient edematous areas known as Calabar swellings. The larvae produced by the females enter the blood stream where they are found in the peripheral vessels during the day time, contrary to the habits of the larvae of Filaria bancrofti. Because of this characteristic periodicity of the larvae, Filaria loa has been also named F. dkirna. The larvae of F. loa are provided with a sheath relatively much longer than that of the larvae of F. bancrofti. Experiments with various anopheline and culicine mosquitoes, and Glossina palpalis have given negative results as to the possibility of these insects acting as intermediate hosts. From Leiper's (1913) researches, it would appear that a species of Chrysops (probably C. dimidiata or C. loTigicornis) acts as the intermediate host of Filaria loa, the larvae undergoing their development in the salivary glands of the insect. Ac- cording to Ringenbach and Guyomarc'h (1914), the intermediate host in the Congo is Chrysops centuHonis. Kleine (1915) in West Africa found 32 out of 600 Chrysops examined, to be infested with larval nematodes which he took to be the larvae of F. loa though he does not give sufficient evidence to support his claims. Filaria demarquayi Manson, 1895 This parasite, generally considered identical with Filaria juncea and F. ozzardi, occurs in man in the West Indies and in British Guiana. The adult has been found in the mesentery and under the peritoneum of the abdominal wall. The first-stage larvae occur in the blood stream. Their appearance in the circulation is not periodic. According to Low (1902) 72 SANITARY ENTOMOLOGY the larvae can be developed to the so-called "sausage" stage in Aedes argenteus {Stegomyia calopus). Experiments with Anopheles albimanus (albipes), Cidex taeniatus, C. quinquefasciatus (fatigans), and other mosquitoes, fleas, and ticks failed to result in any development of the larvae. Fulleborn (1908) was able to develop the larvae to the sausage stage in Anoplieles tnacvlipennis and Aedes argenteus {Stegomyia calo- pus), but no development occurred in the tick, Ornifhodoros mouhata. Further investigations are necessary to determine what insects serve as intermediate hosts for F. demarquayi. Filaria philippinensis Ashburn and Craig, 1906 The adult stage of this parasite of man is unknown. The first-stage larvae occurring in the blood of man are morphologically identical with those of Filaria bancrofti. Unlike the latter, however, the}' show no periodicity. Ashburn and Craig (1907) have shown that the larvae will undergo development in mosquitoes, Cvlex quinquefasciatus (fatigans), similar to that of the larvae of F. bancrofti. It is questionable whether F. philippinensis should be recognized as a distinct species. Filaria tucumana Biglieri and Araoz, 1917 This species, the adults of which are unknown, is based on microfilariae found frequently in the blood of human beings in Argentina. It appears to be comparatively harmless. Biglieri and Araoz (1917) conclude that mosquitoes act as intermediate hosts and apparently consider Aedes argenteus {Stegomyia calopus) the most important vector, though defi- nite proof of this has not been, obtained. Filaria cypseli^ Annett, Dutton and Elliott, 1901 The adult stage of Filarial cypseli occurs in the subcutaneous tissue of the head of the swift, Cypselus affinis, also beneath the subcranial fascia. The embryos or first-stage larvae occur in tlic lymph and rarely in the peripheral blood of infested birds. Dutton (1905) has described various larval stages of the parasite which he finds in an undetermined species of bird-louse belonging to the subfamily Leiothinae that occurs on swifts. The first-stage larva as it is found in the blood of the bird and the stomach of the louse is provided with a sheath as in various other species of Filaria. This sheath is lost and the larva probably soon penetrates the stomach wall. The next stage of the parasite is found in the fat-body of the louse as are two later stages described by Dutton. The last stage of development seen by him is found free in the body RELATION OF INSECTS TO THE PARASITIC WORMS 73 cavity and this is probably the stage in which the parasite is trans- ferred to the bird ; whether as a result of ingestion of the louse by the swift, or as a result of the active migration of the worm from the louse while the insect is engaged in biting, has not been determined. Filaria martis Gmelin, 1790 Filaria martis (or Filaria quadrispina) according to various writers occurs in its adult stage beneath the skin and in the abdominal and thoracic cavities of Mustela foina. Baldasseroni (1909) has found filaria embryos in the intestine of ticks (Ixodes ricinus) taken from a marten harboring the adult nematode, and he suggests that ticks may act as intermediate hosts. As in the case of AcantJiocheilonema grassii, further evidence is necessary before ticks can be considered to play a part in the life history of Filaria martis. Dirofilaria immitis (Leidy, 1856) Railliet and Henry, 1911 This nematode, sometimes erroneously listed as a parasite of man, lives in the right side of the heart and pulmonary artery of the dog. The larvae are found in the circulation, most numerous at night as in the case of Filaria bancrofti. As would be expected from the location of the adult parasite it may give rise to serious symptoms, and affected dogs commonly succumb to the disturbances which it causes. It is a troublesome parasite among hunting dogs in the Southern United States. Noe (1900) showed that the larvae of this nematode continue their de- velopment in certain species of mosquitoes when sucked up with the blood of infested dogs. In 24< to 36 hours after reaching the stomach of the mosquito the larvae pass into the Malpighian tubules. They undergo a certain growth and development in this location, and 11 or 12 days after reaching the mosquito they break out of the tubules, enter the body cavity, and migrate to the labium. From the labium of the mosquito they reach their final host, the dog, in the same manner as F. bancrofti reaches its human host, namely, by breaking through thin portions of the cuticle of the labium at tlie time the mosquito is engaged in biting its victim and then penetrate the skin, finally migrating to the heart. Mosquitoes infested with the larvae of D. immitis are commonly killed by the parasites owing to their destructive action on the ^lalpighian tubules, Noe having observed that only about half the nios(|uitoes that become infested survive. In Italy the common intermediate hosts appear to be Anopheles maculipennis, A. bifurcatus. A, (Myzorh/jnchus) sinensis pseudopictus, and A. (Mijzomyia) superpictus among anophelines; culi- cines, according to Noe such as Culex penicillaris, C. malariae, and ex- ceptionally C. pipiens, can also act as intermediate hosts. 74 SANITARY ENTOMOLOGY Dirofilaria repens, Railliet and Henry, 1911 In the adult stage this nematode, wliich is a very similar parasite to D. immitis, occurs in the subcutaneous connective tissue of the dog. Its larvae enter the blood stream whence they are liable to be ingested by blood-sucking insects. According to Bernard and Bauche (1913) the vellow fever mosquito Aedes argenteus {Siegomyia calopus) acts as the intermediate host. These investigators while admitting that other species of mosquitoes might act as intermediate hosts of D. repens, found that A. argenteus best fulfilled the natural conditions for the transmission of the parasite, and their experiments were carried out with this species of mosquito. They followed the various stages in the development of the larval nematodes in mosquitoes fed experimentally upon infested dogs. About 2 days after the mosquito has been fed the nematode larvae leave the lumen of the alimentary tract and penetrate into the Malpighian tubules where they undergo most of their growth and development. By the eighth day the larvae may be found in some cases to have migrated into the body cavity and thoracic muscles and the last stage of develop- ment in mosquitoes may be found in the proboscis as early as the ninth day. Six young dogs (10 days old) were submitted to the bites of A. argenteus (fed 10 to 15 days previously on infected dogs) every morn- ing for fifteen days. Six young dogs of the same age were kept as con- trols, not exposed to mosquito bites. The bitten dogs all died within thirty days. Ecchymotic spots were found beneath the skin at the points of the mosquito bites, but no filarias were discovered. The other dogs all survived the experiment. Under natural conditions the youngest dogs found infested with D. repens by Bernard and Bauche were at least a year old, hence the writers conclude that the development of the parasite is very slow. Although they did not succeed in completing their experi- ments by recovering the adult stage of the parasite in dogs, following bites by infected mosquitoes, it appears safe to conclude that D. repens is transmitted by mosquitoes in a manner similar to that in which D. immitis is transmitted. Acanthocheilonema perstans (Manson, 1891) Railliet, Henry and Langeron, 1912 This parasite occurs in man in tropical Africa and British Guiana, the adults in the intraperitoneal connective tissue and fatty tissue of the abdominal viscera and pericardium, and the first-stage larvae in the blood stream. The larvae exhibit no periodicity in their appearance in the circulation, the name perstans having reference to this fact. Christy (1903) has suggested that Ornithodoros monbata may act as RELATION OF INSECTS TO THE PARASITIC WORMS 75 the intermediate host of Acanthocheilonema perstans. Wellman (1907) has reported that the larvae of this parasite are taken up by Ornithodoros moubafa and according to liis statements develop very slowly in this tick, advanced stages not being found until more than two months after infection of the tick. The suggestion made by Feldmann (1905), influ- enced b}' Bastian (1904'), that the larvae of A. perstans may pass out of the body of the tick with its eggs into bananas and afterwards being swallowed with this fruit by human beings is a mode of infection which requires no consideration as a possibility without more supporting evi- dence than has yet been advanced. Hodges (1902) obsem'ed Filaria larvae in the thoracic muscles of the mosquitoes, PanopUfes sp. and Aedes argenteus {Stegomyia calopiis), three daA's after they had been fed on perstans blood. Low (1903) was able in one case to obtain development of perstans larvae to the sausage stage in a mosquito {Chrysoconops fuscopennatus). Fullebom (1908, 1913) obtained a similar development in Anopheles maculipennis. Fiille- born and Low obtained negative results with various species of mosquitoes, sand fleas, lice and simuliids. Acanthocheilonema grassii (Noe, 1907) Railliet, Henry and Langeron, 1912 The adults of this nematode occur in the subcutaneous and intermus- cular connective tissue and peritoneal cavity of the dog. The larvae produced by the females are unusually large, about twice as long and thick as the average filaria larva, and according to Noe (1907, 1908) do not pass into the blood stream as is generally the case among the filarias. Noe assumed that the larvje are restricted to the lymphatic system, and accordingly concluded that the intermediate host would most likely be a tick or similar slow feeding ectoparasite. In fact he found nematode larvae corresponding to those of A. grassii in RJiipicephalus sanguineus, a tick of common occurrence in regions where the dogs are infested with the nematode in question. Furthermore he states that all of the ticks attached to dogs infested with the nematode become infested with the larval worms. Additional evidence that R. sanguineus acts as tlie intermediate host is that the larvae in the ticks undergo growth and development, at least one molting period having been observed between successive stages. As R. sanguineus is a tick which falls to the ground to transform from the nymphal to the adult stage, the necessary opportunity is aff"orded for the transmission of A. grassii from one dog to anotlier. Noe remarks that the nymph of this tick ingests large quantities of lymph. The larval nematodes taken in with the ingested lymph penetrate the intestinal wall into the body cavity where they undergo the develop- 76 SANITARY ENTOMOLOGY ment necessary before they are ready to be returned to the definitive host, after transformation of the nymphal tick to the adult stage. Noe be- lieves that the dog becomes infected during the initial phase of attach- ment of the adult. He also suggests that adult males which, unlike adult females, may pass from one host to another are capable of acquiring infection from one dog and transferring it to another. He has found as many as 22 larvae of A. grassii in one male tick. Noe is of the opinion that the larvae escape through thin portions of the cuticle of the mouth parts of the tick and thus reach the final host in a way similar to that followed by the larvae of D. immitis and other filarias trans- mitted by mosquitoes. It is of interest to note that Grassi and Calandruccio (1890) found larval nematodes in Bhipicephalus siculus {^=R. sanguineus) which they identified as the larvae of Filaria recondita {=Acanthocheilonema recon- ditum). Noe thinks that these larvae may have been A. grassii rather than A. reconditum. Evidently further investigations into the life history of A. grassii are necessary before ticks can be accepted as the intermediate host of this parasite. Acanthocheilonema reconditum (Grassi, 1890) Railliet, Henry and Langeron, 1912 This nematode is a parasite of the dog and in the adult stage has been collected fro'm adipose tissue in the neighborhood of the kidney. Accord- ing to Grassi and Calandruccio (1890) the first-stage larvae occur in the blood stream, and are the so-called Haematozoa of Lewis which have been seen by many observers, first by Gruby and Delafond (1843), after- wards by Lewis and others. Apparently, however, the larvae seen in the blood of dogs by Grassi and Calandruccio as well as those known as Lewis's Haematozoa are in reality the larvae of Dirofilaria repens. Grassi and Calandruccio describe various stages of nematode larvae found in fleas (Ctenocephalus canis, C. felis, and Pulex irritans) and in a tick (Rhipicephalus siculus^=^R. sanguineus) as developmental stages in the life history of A. reconditum. According to Noe (1907, 1908), the larvae found in R. sanguineus by Grassi and Calandruccio were probably those of Acanthocheilonema grassii. Owing to the confusion existing with reference to the identity of the parasite that Grassi and Calandruccio studied, the species to which the larval nematodes observed in fleas belong, is uncertain, Grassi and Calan- druccio's experiments can not be considered conclusive so far as con- cerns the life history of A. reconditum. RELATION OF INSECTS TO THE PARASITIC WORMS 77 Setaria labiato-papillosa (Alessandrini, 1838) Railliet and Henry, 1911 The adults of this nematode are common parasites in the peritoneal cavity of cattle in various parts of the world including the United States. The larvae enter the blood stream, and Noe (1903) identifies certain larval nematodes found in Stomoxys calcitrans as belonging to this species. That this fly actually serves as the intermediate host, however, remains to be proved. The possibility is not excluded that Noe mistook Hahronema larvae for the larvjB of .S". labiato-papillosa. Oncocerca About twelve species of this genius have been described. Onco- cerca volvulus in the adult stage occurs in nodular tumors beneath the skin of man in Africa. Oncocerca caecutiens is found in subcutaneous nodules on the head among natives living at a certain altitude on the west coast of Guatemala and is the cause of so-called "Coast erysipelas." O. gibsoni causes worm nodules in the brisket and other locations in cattle in Australia. Two species occur in cattle in the United States: one undetermined species is found in relation with the ligaments of the legs and neck, the other (0. lienalis) is found in the gastrosplenic liga- ment. Oncocerca larvae have not been found in the blood stream but may be recovered from the lymph spaces in the neighborhood of the adult worms. The intermediate hosts of these nematodes are unknown but biting insects have been suspected. The results of experiments have been nega- tive. Brumpt (1903) has suggested the possibility that Glossina palpalis acts as intermediate host of 0. volvulus. Robles (1919) suggests that two species of Simulium (close to S. din^lli and S. samboni) may be involved as vectors of 0. caecutiens in view of the fact that these flies are most numerous in the places where the largest number of cases of Oncocerca occur. Furthermore these species of flies are absent in lower altitudes corresponding with the absence of Oncocerca. 3. Other Nematodes Diff'erent investigators have recorded the occurrence of larval nema- todes of unknown species in various insects. Usually these have been very poorly described and it is questionable in many cases whether if found again they could be recognized as the same forms. Some of them may be the larval forms of nematodes whose adults are already known as parasites of higher animals. Among such larvae of uncertain identity may be mentioned Filaria geotrupis in the abdominal cavity 78 SANITARY ENTOMOLOGY of Geotrupes stercorarius (possibly the larva of Physocephalus sexala- tus), Filaria ephemeridarum in the abdominal cavity of the larvae of Ephemera vulgafa and OUgoneuria rhenana, Filara ri/tipleuritis (of Magalhacs, 1900, not Deslongchamps, 1824) in the abdominal cavity of Periplamta americana (possibly a Gongylonema according to Seurat), Filaria stomoxeos in Stomoxys calcitrans (possibly the larva of Hab- ronema microstoma), Mastophorus echiurus, and Cephalacanthus mona- canthus in Tenehrio vioUtor (probably larvae of Protospirura miiris), Mastophorus glohocandatus and Cephalacanthus triacanthus in Geotrupes stercorarius (possibly larvae of Physocephalus sexalatus). 4. Mermithidae These worms which resemble the nematodes and are usually grouped with them are not known to be of importance in medical zoology. One species, of uncertain identity, is of interest, however, as it is the so-called "cabbage snake" whose presence among the leaves of cabbage has alarmed people who have encountered it. This worm, like others of the same family, undoubtedly passes through a portion of its development in the body of an insect, probably one of the common caterpillars that attack cabbage. Similar worms have been found in apples. GORDIACEA OR HORSE-HAIR WORMS The Gordiacea or horse-hair worms (as which they are popularly known from the superstitious belief that they are animated horse hairs) are of medical interest because several species have been recorded as parasites of man. They gain entrance to the alimentary tract by being swallowed in drinking water. The adults are of not uncommon occur- rence in springs and other surface waters. When swallowed by human beings they are usually soon vomited up but they have in some cases apparently survived in the intestine for several months before the}^ were finally expelled. In some species, and probably in all, insects serve as hosts for the larval stages. The adults deposit their eggs in the water in which they live. The larvae hatching from the eggs enter the bodies of insects such as grasshoppers (as for example, in the case of Gordius rohustus) or crickets (as for example, in the case of Paragordius varius) or in the case of other species they may enter aquatic insect larvae, which may later be devoured by carnivorous water insects. In the latter the worms undergo their development until they have reached or ap- proached maturity when they burst out of the infested insect and escape into the water. The following species of Gordiacea have been recorded as accidental parasites of man: Gordius aquaticus, G. chilensis. Para- RELATION OF INSECTS TO THE PARASITIC WORMS 79 gordius varius (a common American species), Paragordius tricuspidatus^ Parachordodes tolusanus, Parachordodes violaceus, Parachordodes pus- tulosus, and Chordodes alpestris. ACAXTHOCEPHALA OR TIIORX-HEADED WORMS This highly specialized group of parasites, commonly classified in the Nematlielminthes, with which it has little in common beyond a superficial resemblance in the general shape of the body, has been but little studied. Most of the known species are parasitic in birds. Macrae anthorhyncluis liirudinaceus (Pallas, 1781) Travassos, 1916 This worm in the adult stage (sometimes called the giant thorn- headed worm) is a common parasite of the intestine of the pig and is said to occur as a parasite of man along the River Volga. Its eggs pass out of the body of the host in the feces. Swallowed by certain insects [larvae of Melolontha melolontha, Cefonia aurata, Pliyllophaga arcuata {Lach- nosterna), and DUoboderus ahderibs^ the eggs hatch, and the larvae develop into an intermediate stage, which in turn completes its develop- ment to maturity when the infested grub is eaten by a pig. Moniliformis moniliformis (Bremser, 1819) Travassos, 1915 This parasite in its adult stage (sometimes called the beaded thorn- headed worm) is of common occurrence in the intestine of rats and other rodents in tropical and subtropical regions, and has been f(jund in man in Italy. The life cycle is similar to that of the giant thorn-headed worm except for the diff'erence in hosts. According to Grassi and Calandruccio (1888), Blaps mucronata acts as an intermediate host. According to Magalhaes (1898) and Seurat (1912), the usual intermediate host is a cockroach (Periplaneta americana). COMPENDIUM OF PARASITES ARRANGED ACCORDING TO INSECT HOSTS ^ Aphaniptera (SipJionaptera) — fleas Ceratophyllus fasciatus Bosc Hymenolepis diminuta ? Hymenolepis nana Ctenocephalus canis Curtis ? Aca/nthocheilonema reconditum 'The scientific names of the insects have been revised bv the editor. 80 SANITARY ENTOMOLOGY Dipylidium caninum Hymenolepis diminuta Ctenocephalus felis Bouche ? Acantliocheilonema reconditum ? Dipylidium caninum Pulex irritans Linnaeus ? Acantliocheilonema reconditum Dipylidium caninum Hymenolepis diminuta Xenopsylla chcopis Rothschild Hymenolepis diminuta ? Hymenolepis nana ? Protospirura muris Diptera — flies Aedes argenteus Poirret (Stegomyia calopus Meigen) Acanthocheilonema perstans (incomplete development) Dirofilaria repens Filaria hancrofti Filaria demarquayi (incomplete development) ? Filaria tucumana Aedes gracilis Leicester (Stegomyia) Filaria hancrofti Aedes scutellaris Walker (Culex albopictus Skuse) Filaria hancrofti Anopheles barbirostris Van der Wulp (Myzorhynchus) Filaria hancrofti Anopheles bifurcatus Linnaeus DirofilaHa immitis Anopheles costalis Loew (Pyretophorus) Filaria hancrofti Anopheles maculipennis Meigen (claviger Fabricius) Acantliocheilonema perstans (incomplete development) Dirofilaria immitis Filaria demarquayi (incomplete development) Trcmatode RELATION OF INSECTS TO THE PARASITIC WORMS 81 Anopheles rossi Giles (Myzomjia) Trematode Filaria bancrofti Anopheles sinensis Wiedemann ( Myzorhynchus ) Filaria bancrofti Anopheles sinensis peditaeniatus Leicester (Myzorhynchus) Filaria bancrofti Anopheles sinensis pseudopictus Grassi (Myzorhynchus) Dirofilaria immitis Anopheles superpictus Grassi (Myzomyia) Dirofilaria immitis Chironomus plumosus Linnaeus Lecifhodendrium ascidia Chrysoconops fuscopennatus (Theobald) (Taeniorhynchus) Acantliocheilonema perstans (incomplete development) Chrysops spp. Filaria (Loa) loa ? Chr3^sops centurionis Austen Filaria (Loa) loa ? Chrysops dimidiuta Van dcr Wulp Filaria (Loa) loa ? Chrysops longicornis ]Macquart Filaria (Loa) loa Culex gclidus Theobald Filaria bancrofti Culex nialariac Grassi Dirofilaria immitis Culex penicillaris Rondani Dirofilaria immitis 82 SANITARY ENTOMOLOGY Culex pipiens Linnaeus Dirofilaria immitis FUaria bancrofti Culex quinquefasciatus Say (skusei Giles) (fatigans Wiedemann) FUaria bancrofti Culex sitiens Wiedemann FUaria bancrofti Mansonioides annulipes Theobald FUaria bancrofti Mansonioides uniformis Theobald FUaria bancrofti Musca domestica Linnaeus Ch o a n o taenia infundibulum Hahronema muscae Habronema microstoma Hahronema megastoma ? Davainea cesticillus ? Davainea tetragona Panoplites sp. Acanthocheilonema perstans (incomplete development) Scutomyia albolineata Theobald FUaria bancrofti Stomoxys calcitrans Linnaeus FUaria stomoxeos Habronema microstoma ? Hahronema muscae ? Setaria lahiat o-papillosa ? Hymenolepis carioca Taeniorhynchus domesticus Leicester FUaria bancrofti Neuroptera Sialis lutaria (Linnaeus) Treniatodc RELATION OF INSECTS TO THE PARASITIC WORMS 83 Trichoptera — ^hairy-winged insects Anabolia nervosa (Leach) Curtis AUocreadium isoporum Opisthioglyphe rasfellus Chaetopteryx villosa (Fabricius) AUocreadium isoporum Drusus trifidus McLachlan Trematode Limnophilus flavicornis (Fabricius) Opisthioglyphe rastellus Limnophilus griseus (Linnaeus) Opisthioglyplie rastellus Limnophilus lunatus (Curtis) Opisthioglyphe rastellus Limnophilus rhombicus (Linnaeus) Opisthioglyphe rastellus Mystacides nigra (Linnaeus) Trematode Notidobia ciliaris (Linnaeus) Trematode Phryganea grandis Trematode Phryganea sp. Lecithodendrium chilostomum Rhyacophila nubila Zetterstedt Trematode Lepidoptera — moths, butterflies Asopia farinalis (Linnaeus) Hymenolepis diminuta Nymphula nymphaeata (Linnaeus) (Hydrocampa) Trematode 84 SANITARY ENTOMOLOGY Coleoptera — beetles Akis goryi (Solier) Spirocerca sanguinolenta Spirura gastropJiila Akis spinosa (Linnaeus) Hymenolepis dimmuta Aphodius rufus (Moll) var. castaneus Marsh ArdueTvna strongylina Aphodius coloradensis Horn Gongylonema scufatum Aphodius femoralis Say Gongylonema scutatum Aphodius fimctarius Linnaeus Gongylonema scutatum Aphodius granarius Linnaeus Gongylonema scutatum Aphodius vittatus Say Gongylonema scutatum Blaps appendiculata Gongylonema sp. (G. scutatum according to Seurat) Blaps sp. Gongylonema brevispiculum Blaps sp. (near appendiculata) Spirura gastrophila Gongylonema sp. (G. scutatum according to Seurat) Blaps cmondi Gongylonema sp. (G. scutatum according to Seurat) Blaps mucronata Latreille Moniliformis moniliformis Blaps strauchi Reiche Spirura gastrophila Gongylonema sp. {G. scutatum according to Seurat) RELATION OF INSECTS TO THE PARASITIC WORMS 85 Cetonia aurata (Linnaeus) M acracanthorhynchus hirudinaceus Copris hispanus (Linnaeus) Spirocerca sanguinolenta Diloboderus abderus Sturm M acracanthorliynclius hirudinaceus <^ — Geotrupcs douei Gory ? Gongylonema mucronatum Spirocerca sanguinolenta Physocephalus sexalatus Geotrupes stercorarius (Linnaeus) Cephalacantlius triacanthus Filaria geotrupis Mastopliorus glohocaudatus ? Physocephalus sexalatus Gymnopleurus mopsus (Pallas) ? Gongylonema mucronatum Gymnopleurus sturmi Mae Leay ? Gongylonema mucronatum Spirocerca sanguinolenta Ilybius fuliginosus (Fabricius) Haplometra cylindracea Melolontha melolontha Linnaeus (vulgaris Fabricius) M acracanthorhynchus hirudinaceus Chironitis irroratus Rossi (Onitis) ? Gongylonema mucronatum Onthophagus spp. Arduemia strongylina Spirura gastrophila Ontliophagus bedeli Neitt. ? Gongylonema mucronatum Physocephalus sexalatus 86 SANITARY ENTOMOLOGY Onthophagus hecate Panzer Gongylonema scut a turn Onthophagus ncbulosus Reiche Fhysocephalus sexalatus Onthopliagus pennsylvanicus Harold Gongylonema scutatum Phyllophaga arcuata Smith (Lachnosterna) Macracanthorhynchus hirudinaceus Scarabaeus (Ateuchus) sacer Linnaeus ? Gongylonema mucronatum Fhysocephalus sexalatus Spirocerca sanguijiolenta Scarabaeus (Ateuchetus) variolosus Fabricius Physocephalus sexalatus ? Spirocerca sanguinolenta Scaurus striatus Fabricius Hymenolepis diminuta Tenebrio molitor Linnaeus Cephal acanthus monacanthus Gongyloneina neoplasticum Hymenolepis diminuta ? Hymenolepis microstoma Mastophorus echiurus Protospirura muris Water beetles Pleurogenes claviger Pleurogenes medians Prosotocus confusus Mallophaga — bird lice Leiothinae ( ? genus ? species) Filaria cypseli Trichodectes latus Nitzsch (canis DeGeer) Dipylidium caninum RELATION OF INSECTS TO THE PARASITIC WORMS 87 I so pt era — termites Hodotermes pretoriensis Fuller Filaria aallinarum Odonata — dragonflies Aeschna sp. Prosotocus confusus Agrion sp. Gorgodera pagenstecTieri Gorgodera varsoviensis Pleurogenes medians Calopteryx virgo (Linnaeus) Halipegus ovocaudatus Pneumonoeces similis Cordulia sp. Prosotocus confusus Epitheca spp. Gorgodera cygnoides Gorgodera pagenstecheri Gorgodera varsoviensis Plectoptera — mayflies Cloeon dipterum (Linnaeus) Stephens ? Opisthioglyphe rastellus Ephemera vulgata Linnaeus Allocreadium isoporum Filaria ephemeridarum ? Opisthioglyphe rastellus Ephemeridae Lecithodendrium ascidia Oligoneuria rhenana ImhofF Filaria ephemeridarum 88 SANITARY ENTOMOLOGY Plecoptera — stoneflies Perlidae Lecithodendrium ascidia Trematode Orthoptera — cockroaches, etc, Blattella germanica (Linnaeus) Caudell Gongylonema neoplasticum Gongylonema scutatum (experimental infection) Periplaneta americana (Linnaeus) Burmeister Filaria rytipleuritis of Magalhaes, 1900 Gongylonema neoplasticum Moniliformis moniliformis Blatta orientalis Linnaeus Gongylonema neoplasticum ? Spirocerca sanguinolenta Spirura gastrophila Dermaptera — earwigs Anisolabis annulipes Lucas Hymenolepis diminuta Myriapoda — millipedes, centipedes ^ Fontaria virginiensis (Drury) Hymenolepis diminuta Glomeris limbata Tapeworm larvae Julus sp. Hymenolepis diminuta Julus guttulatus Nematode larva Acarina — ticks, mites ^ Ixodes ricinus (Linnaeus) Latreille ? Filaria martis ^ Included in list because of their similarity to insects. RELATION OF INSECTS TO THE PARASITIC WORMS 89 Ornithodoros moubata (Murray) ? Acanthocheilonema perstans Rhipicephalus sanguineus (Latreille) ? Acanthocheilonema grassii ? Acanthocheilonema reconditum Isopoda — sowbugs * Porcellio laevis Latreille ? Acuaria spiralis LIST OF REFERENCES Ackert, James E. 1918. — On the life cycle of the fowl cestode, Davainea cesticillus (Molin). (Preliminary communication.) Jour. Parasit. Ur- bana, 111., Vol. 5, No. 1, Sept., pp. 41-43, pi. 5, figs. 1-4. 1919. — On the life history of Davainea tetragona (Molin), a fowl tapeworm. Jour. Parasit., Urbana, 111., Vol. 6, No. 1, Sept., pp. 28-34. Ashbum, P. M., and Craig, Charles F. 1907. — Observations upon Filaria philippvnensis and its development in the mosquito. Philippine Journ. Sci., vol. 2B, No. 1, Mar., pp. 1-14, pis. 1-7, figs. 1-26. Baldasseroni, Vincenzo. 1909. — "Ixodes ricinus" L. infetto da embrioni di Filaria. Bull. Soc. Entom. Ital., vol. 40, Nos. 3-4, pp. 171-174, Dec. 30. Bancroft, Thomas L. 1901. — Preliminary notes on the intermediate host of Filaria immitis Leidy. Journ. Trop. Med. Lond., vol. 4, Oct. 15, pp. 347-349- Bastian, H. Charlton. 1904. — Note on the probable mode of infection of the so-called Filaria perstans, and on the probability that this organism really belongs to the genus Tylenchus (Bastian). Lancet, vol. 166, No. 4196, vol. 1, No. 5, Jan. 30, pp. 286-287, figs. 1-3. Bernard, P. Noel, and Bauche, J. 1913. — Conditions de propagation de la filariose sous-cutanee du chien. Stegomyia fasciata bote intermediaire de Dirofilaria repens. Bull. Soc. Path. Exot., vol. 6, No. 1, Jan. 8, pp. 89-99, figs. 1-9. * Included in list because of their similarity to insects. 90 SANITARY ENTOMOLOGY Biglieri, R., and Aivioz, J. M. 1917.^ — Contribucion al estudio de una nueva filariosis humana encon- trada en la Ropublica Argentina (Tucuman), ocasionada por la ^'FUaria tucumana.''' 1. Confer. Soc. sud-am. de hig. [etc.], Buenos Aires Sept. 17-24, 1916, pp. 403-422. Brumpt, Emile. 1903. — Sur role des mouches tse-tse en pathologie exotique. Compt. Rend. Soc. Biol., vol. 55, No. 34, Dec. 4, pp. 1496-1498. Bull, Lionel B. 1916. — A granulomatous affection of the horse — Habronemic granu- loniata (cutaneous habronemiasis of Railliet). Journ. Comp. Path, and Therap., vol. 29, No. 3, Sept. 30, pp. 187-199, figs. 1-5. 1919. — A contribution to the study of habronemiasis : A clinical, pathological, and experimental investigation of a granulomat- ous condition of the horse-habronemic granuloma, pp. 85-141, pis. 13-15, figs. 1-8. [Reprint from Tr. Roy. Soc. South Australia, v. 43.] Christy, Cuthbert. 1903. — The distribution of sleeping sickness, Filaria perstans, etc., in East Equatorial Africa. (Preliminary report dated Oct. 31, 1902). Roy. Soc. Rep. Sleep.-Sick. Comm., No. 2, Nov., pp. 3-8, 3 maps. De Magalhaes, Pedro Severiano. 1898. — Notes d'helminthologie bresilienne. [5. note] Arch. Parasitol., vol. 1, No. 3, July, pp. 361-368, figs. 1-4. 1900. — Notes d'helminthologie bresilienne. [8. note] Arch. Parasitol., vol. 3, No. 1, May 15, pp. 34-69, figs. 1-25. Descazeaux, J. 1915. — Contribution a I'etude de 1' "csponja" ou plaies d'ete des equides du Bresil. (Rapport de Railliet, 17 juin). Bull. Soc. Centr. de Med. Vet., vol. 69, Jan. 30-Sept. 30, pp. 468-486, figs. 1-3. Deslongchamps, Eugene Eudes. 1824.— Filaire. Filaira. Encycl. Methodique, vol. 2, pp. 391-397. RELATION OF INSECTS TO THE PARASITIC WORMS 91 Dutton, J. Everett. 1905. — The intermediary liost of Filaria cypseli (Annett, Dutton, El- liott); the Filaria of the African swift, Cypselus affinis. Thompson Yates & Johnston Lab. Rep., Lond., n. s., vol. 6, No. 1, Jan., pp. 137-147, pi. 5, figs. i-x. Feldmann. 1905. — Ueber Filaria perstans im Bezirk Bukoba. Arch. f. Schiffs- u. Tropen-Hyg., vol. 9, No. 2, Feb., pp. 62-65, 2 pis. Fibiger, Johannes, and Ditlevsen, Hjalmar. 1914. — Contributions to the biology and morphology of Spiroptera {Gongylonema) neoplastica n. s. Mindeskr. Japetus Steen- strups Fodsel, 2. Halvbind, 28 pp., figs. 1-3, pis. 1-4, figs. 1-32. FiiUeborn, Friedrich. 1908. — Ueber Versuche an Hundefilarien und deren Ubertragung durch Miicken. Beihefte (8) z. Arch. f. SchifFs- u. Tropen-Hyg., vol. 12, Nov., pp. 313-351 (43 pp.), figs. 1-6, pis. 1-4, figs. 1-38. 1908. — Untersuchungen an menschlichen Filarien und deren Uber- tragung auf Stechmiicken. Beihefte (9) z. Arch. f. SchifFs- u. Tropen-Hygr., vol. 12, Nov., pp. 357-388 (36 pp.), figs. 1-3, p4s. 1-7, figs. 1-132. 1913. — Die Filarien des Menschen. Handb. d. path. jNIikroorganism. (Kolle & Wassermann), Jena, 2. Aufl., vol. 8, pp. 185-344, figs. 1-41, pis. 1-6. Galeb, Osman. 1878. — Observations et experiences sur les migrations du Filaria rytipleurites, parasite des blattes et des rats. Compt. Rend. Acad. Sc, vol. 87, No. 2, July 8, pp. 75-77. Grassi, Giovanni Battista. 1887. — Entwickelungscyklus der Tania nana. Dritte praliminamote. Centralbl. f. Bakteriol. (etc.), Jena, 1. Jahr., vol. 2, No. 11, pp. 305-312. 1888. — Ciclo evolutivo della Spiroptera {Filaria) sanguinolenta. Gior. di Anat., Fisiol. e Patol. d. Animali, vol. 20, No. 2, Mar.-Apr., pp. 99-101. Grassi, Giovanni Battista, and Calandruccio, Salvatore. 1888. — Ueber einen Echinorhynchus, welcher auch im Menschen para- sitirt und dessen Zwischenwirth ein Blaps ist. Centralbl. f. 92 SANITARY ENTOMOLOGY Bakteriol. (etc.), Jena, 2. Jahr., vol. 3, No. 17, pp. 521-525, figs. 1-7. 1890.— Ueber Haemaiozoon Lewis. Entwickelungscyklus einer Filaria {Filaria recondita Grassi) des Hundes. Centralbl. f. Bakteriol. (etc.), Jena, vol. 7, No. 1, Jan. 2, pp. 18-26, figs. 1-16. Grassi, Giovanni Battista, and Rovelli, Giuseppe. 1888.— Intorno alio sviluppo cestodi. Nota preliminare. Atti R. Accad. d. Lincei, Roma, Rendic, an. 285, 4. s., vol. 4, 1. semestre, No. 12, June 3, pp. 700-702. 1888.— Bandwurmerentwickelung. Centralbl. f. Bakteriol. (etc.), Jena, 2. Jahr, vol. 3, No. 6, p. 173. 1889.— Sviluppo del cisticerco e del cisticercoide. Nota preliminare. Atti R. Accad. d. Lincei, Roma, Rendic, an. 286, 4. s., vol. 5, 1. semestre, No. 3, Feb. 3, pp. 165-174, figs. 1-4. 1892._Ricerche embriologiche sui cestodi. Atti Accad. Giornia di Sc. Nat. in Catania (1891-92), an. 68, 4. s., vol. 4, 2. mem., 108 pp., 4 pis. Gruby, David, and Delafond, Henri-Mamert-Onesius. 1843.— Note sur une alteration vermineuse du sang d'un chien deter- minee par un grand nombre d'hematozoaires du genre filaire. Compt. Rend. Acad. Sc, vol. 16, No. 6, Feb. 6, pp. 325-326. Guberlet, John E. l916._Morphology of adult and lai-val cestodes from poultry. Irans. Am. Micr. Soc, vol. 35, No. 1, Jan., pp. 23-44, pis. 5-8, figs. 1-30. 1919,_On the life history of the chicken cestode, Hymenolepis canoca (Magalh'aes). Journ. Parasit., vol. 6, No. 1, Sept., pp. 35-38, pi. 4, figs. 1-6. Hill, Gerald F. . ^ ^ ^- 1918._Relationship of insects to parasitic diseases in stock. Pp. ii- 107, pis. 2-8, figs. 1-49A. 8°. Melbourne. [Reprint from Proc Roy. Soc. Victoria, new ser., v. 31, pt. 1.] Hodges, Aubrey. l902._Sleeping-sickness and Filaria perstans in Busoga and its neigh- borhood, Uganda Protectorate. Journ. Trop. Med., vol. 5, No. 19, Oct. 1, pp. 293-300, 1 map, 1 pi., figs. 1-2. Johnston, T. Harvey. i ■, i oa 1913 —Notes on some Entozoa. Proc. Roy. Soc. Queensland, vol. ^^, pp. 63-91, pis. 2-5, figs. 1-45. (Advance separate issued Nov. 1, 1912). RELATION OF INSECTS TO THE PARASITIC WORMS 93 Joyeux, Ch. 1916. — Sur le cycle evolutif de quelques cestodes. Note preliminaire. Bull. Soc. Path. Exot., vol. 9, No. 8, Oct. 11, pp. 578-583. Kleine, F. K. 1915. — Die Ubertragung von Filaricn durch Chrysops. Zeitschr. f. Hyg. u. Infektionskrankh., vol. 80, No. 3, Oct. 26, pp. 3-i5-S49. Lebredo, Mario G. 190-i.^ — Filariasis. Nota preliminar deducida de expcriencias prficticas, que demuestran el sitio por donde la Filaria nocinrna abandona el Culex pipiens infectado. Rev. Med. Trop., Habana, vol. 5, No. 11, Nov., pp. 171-172. 1905. — Metamorphosis of Filaria in the bod^^ of the mosquito (Culex pipiens). Journ. Infect. Dis., Suppl. (1), May, pp. 332- 352, pis. 1-3, figs. 1-16. Leiper, Robert T. 1913. — ^[]Metamorphosis of Filaria Zoa.] [Telegram to London School Trop. Med., Dec. 27, 1912]. Lancet, No. .1662, vol. 184, vol. 1, No. 1, Jan. 4, p. 51. Leuckart, Karl Georg Friedrich Rudolph. 1867. — Die menschlichen Parasiten und die von ihnen herriihrenden Krankheiten. Ein Hand- und Lehrbuch fiir Naturforscher und Aerzte. Vol. 2, 1. Lief., vi. 256 pp., 158 figs. Leipzig & Heidel- berg. Low, George C. 1902. — Notes on Filaria demarquaii. Brit. Med. Journ., No. 2143, vol. 1, Jan. 25, pp. 196-197. 1903. — Filaria pe'rstans. Brit. Med. Journ., No. 2204, vol. 1, Mar. 28, pp. 722-724, figs. 1-2. Manson, (Sir) Patrick. 1878. — On the development of Filaria sanguinis Jwminis, and on the mosquito considered as a nurse. Journ. Linn. Soc. Lond., Zool. (75), vol. 14, Aug. 31, pp. 304-311. Marchi, Pietro. 1867. — Monografia sulla storia genetica e sulla anatomia dolla Spiroptera obtusa Rud., 34 pp., 2 pis. fol. Torino. [Advance separate from Mem. R. Accad. Sc. Torino, CI. d. Sc. Fis., Mat. e Nat., 2. s., vol. 25, issued in 1871.] 94 SANITARY ENTOMOLOGY Mclnikov, Nicolaus. 1869. — Ueber die Jugendzustande der T'fenia cucumerina. Arch. f. Naturg., Berl., 35. Jahr., vol. 1, No. 1, pp. 62-70, pi. 3, figs. a-c. Nickerson, W. S. 1911. — An American intermediate host for Hymenolepis dimirmta. Science, n. s., No. 842, vol. 33, Feb. 17, p. 271. Nicoll, W., and Minchin, E. A. 1911. — Two species of cysticercoids from the rat-flea {Ceratophyllus fasciatus). Proc. Zool. Soc. Lond., No. 1, Mar., pp. 9-13, figs. 1-2. Noe, Giovanni. 1900. — Propagazione delle filarie del sangue esclusivamente per mezzo della puntura della zanzare. 2. Nota preliminare. Atti R. Accad. d. Lincei, Rendic. CI. di Sc. Fis., Mat. e Nat., an. 297, 5. s., vol. 9, 2. semestre. No. 12, Dec. 16, pp. 357-362, figs. 1-3. 1903. — Studi sul ciclo evolutivo della Filaria labiato-papillosa, Ales- sandrini. Nota preliminare. Atti R. Accad. d. Lincei, Rendic. CI. di Sc. Fis., Mat. e Nat., an. 300, 5. s., vol. 12, 2 semestre. No. 9, Nov. 8, pp. 387-393. 1907. — La Filaria grassii, n. sp. e la Filaria recondita, Grassi. Nota preliminare. Atti R. Accad. d. Lincei, Rendic. CI. di Sc. Fis. Mat. e Nat., an. 304, 5. s., vol. 16, 2. semestre, No. 12, Dec. 15, pp. 806-810. 1908. — II ciclo evolutivo della Filaria grassii, mihi, 1907. Atti R. Accad. d. Lincei, Rendic. Cl. di Sc. Fis., Mat. e Nat., an. 305, 5. s., vol. 17, 1. semestre. No. 5, Mar. 1, pp. 282-293, figs. 1-4. Nuttall, George H. F. 1899. — On the role of insects, arachnids, and myriapods as carriers in the spread of bacterial and parasitic diseases of man and animals. A critical and historical study. Johns Hopkins Hosp. Rep., Baltimore, vol. 8, Nos. 1-2, pp. 1-154, pis. 1-3. Plana, Giovanni Pietro. 1897. — Osservazioni sul Dispharagus nasutus Rud. dei polli e sulle larvae nematoelmintiche delle mosche e dei porcellioni. Atti Soc. Ital. Sc. Nat. (etc.), Milano, voh 36, No. 3-4. Feb., pp. 239-262, figs. 1-21. RELATION OF INSECTS TO THE PARASITIC WORMS 95 Ransom, Brayton H. 1911. — The life history of a parasitic nematode — Habronema muscae. Science n. s., No. 881, vol. 34, No. 17, pp. 690-692. 1913. — The life history of Habronema muscae (Carter), a parasite of the horse transmitted by the house fly. U. S. Dept. Agric, Bureau Animal Indust., Bull. 163, Apr. 3, pp. 1-36, figs. 1-41. Ransom, Brayton H., and Hall, Maurice C. 1915. — The life history of Gongylonema scutatuvi. Journ. Parasit., vol. 1, No. 3, Mar., p. 154. 1916. — The life history of Goi}gylonema scutatum. Journ. Parasit., vol. 2, No. 2, Dec, 1915, pp. 80-86. 1917. — A further note on the life history of Gongz/lonema scutatum. Journ. Parasit., vol. 3, No. 4, June, pp. 177-181. Ringenbach, J., and Guyomarc'h. 1914. — La filariose dans les regions de la nouvelle frontiere Congo- Cameroun, Observations sur la transmission de Microfilaria diurna et de Microfilaria perstans. Bull. Soc. Path. Exot., vol. 7, No. 7, July 8, pp. 619-626. Robles, R. 1919. — Onchocercose humaine au Guatemala produisant la cecite et "I'erysipele du littoral" (erisipela de la costa). Bull. Soc. Path. Exot., vol. 12, No. 7, July 9, pp. 442-460, 2 maps, figs. 1-6. Seurat, L. G. 1912. — Sur le cycle evolutif du spiroptere du chien. Compt. Rend. Acad. Sc, vol. 154, No. 2, Jan. 8, pp. 82-84. 1912. — La grande blatte, bote intcrmediaire de I'echinorhynque moniliforme en Algerie. Compt. Rend. Soc. Biol., vol. 72, No. 2, Jan. 19, pp. 62-63. 1913. — Sur revolution du Physocephalus sexalatus (Molin). Compt. Rend. Soc. Biol., vol. 75, No. 35, Dec. 12, pp. 517-520, figs. 1-4. 1913. — Sur revolution du Spinira gastropliila Miill. Compt. Rend. Soc. Biol., vol. 74, No. 6, Feb. 14, pp. 286-289, figs. 1-3. 1916. — Contribution a I'etude des formes larvaires des nematodes parasites heteroxenes. Bull. Scient. France et Belg., 7. s., vol. 49, No. 4, July 6, pp. 297-377, figs. 1-14. 1918. — Extension de Phabitat du Spirura gastropliila (Mueller). Compt. Rend. Soc. Biol., vol. 81, No. 15, July 27, pp. 789-791. 96 SANITARY ENTOMOLOGY 1919. — Contributions nouvelles a I'etude des formes larvaires des nematodes parasites heteroxenes. Bull. Biol. France et Belg. (1918), vol. 52, No. 4, Mar. 25, pp. 344-378, figs. I-XII. Theiler, (Sir) Arnold. 1919. — A new nematode in fowls, having a termite as an intermediary host. IFUaria gallinarum (nova species)]. 5, & 6. Rep. Director Vet. Research, Dept. Agric. Union South Africa (1918), Apr., pp. 695-707, 1 pi., fig. 1. -Van Saceghem, R. 1917. — Contribution fi I'etude de la dermite granuleuse des equides. Bull. Soc. Path. Exot., vol. 10, No. 8, Oct., pp. 726-729. 1918. — Cause etiologique et traitement de la dermite granuleuse. Bull. Soc. Path. Exot., vol. 11, No. 7, July 10, pp. 575-578. Villot, Fran9ois Charles Alfred. 1878. — Migrations et metamorphoses des tenias des musaraignes. Ann. Sc. Nat., Zool., vol. 49, 6. s., vol. 8, Nos. 2-3, art. 5, 19 pp., pi. 11, figs. 1-14. 1883. — Memoire sur les cystiques des tenias. Ann. Sc. Nat., Zool., 6. s., vol. 15, art. 4, Oct., 61 pp., pi. 12, figs. 1-13. Von Linstow, Otto Friedrich Bernhard. 1886. — Ueber den Zwischenwirth von Ascaris lumhricoides L. Zool. Anz., No. 231, vol. 9, Aug. 30, pp. 525-528. Von Stein, Friedrich. 1852. — Beit rage zur Entwickelungsgeschichte der Eingeweidewiirmer. Zeitschr. f. Wissensch. Zool., vol. 4, No. 2, Sept. 2, pp. 196- 214, pi. 10, figs. 1-20. W^ellman, Frederick Creighton. 1907. — Preliminary note on some bodies found in ticks Ornithodoros monbata (Murray) fed on blood containing embryos of Fi- laria perstans (Manson). Brit. Med. Journ., No. 2429, vol. 2, July 20, pp. 142-143. CHAPTER VI The Relations of Climate and Life and Their Bearings on the Study of Medical Entomology.^ W. Dwighf Pierce ^ All animal and plant life has its being and reacts according to defi- nite laws in which we find the climatic factor of primary importance. We cannot go far into a subject with as many inter-relationships as medical entomology without finding it necessary to know something of the climatic laws which govern the lives of the various organisms con- cerned. In several of the lectures attention is especially called to apparent discrepancies in the interpretation of climatic eff'ects on the life of the insects, and this is particularly true in case of the lice. Throughout our literature there is to be found a hazy notion of the importance of temperature and still hazier notions of humidity. There is a great' deal about these factors which help to govern life, that no one knows, but it will pay us to have a clearly defined statement of some of the most important principles as now understood. On a proper understanding of the relations of temperature and humidity to the life and development of insects, animals, and disease organisms, depend all transmission experiments, all efforts in keeping alive the various creatures involved, all interpretations of results and many practical measures of control. This difficult subject will be stated in as simple language as possible so that all may see the basic principles at least. Every one of us knows that cold and heat can cause pain. We have indeed a clear understanding that cold and heat kill. We recognize the fact that we seem to work best under conditions when we are absolutely oblivious of heat or cold, dryness or moisture. We have felt stupid in murky weather. We have felt parched and dried from extremely dry weather. In other words, we can now recognize four conditions which may affect our well-being, cold, lieat, dryness, moisture. These can be expressed on two scales — temperature and relative humidity. In other words, we should be able to chart our own susceptibilities to these factors by running, for example, a temperature scale vertically on our ^This lecture was read July 1, 1918 and issued the same day. 07 98 SANITARY ENTOMOLOGY chart paper and a humidity scale from zero to one hundred per cent saturation horizontally. If we picture our reactions or those of the creature being studied on such a chart (see figs. 8, 9), we will better understand the subject. In the lower part of the chart we will locate certain temperatures which always cause death from cold. These may be known as ABSOLUTE FATAL TEMPERATURES. Now a common failing in the past has been to assume that humidity had nothing to do witli the effect of temperature on life. It does have a very decided bearing. A creature which can stand a certain degree M HrPCfHfriCAL CHART SHOWING TH[ ZO^fS Of LIFE RfACTIONS TO TCMPffiMORE m niKim humidity, OlfftRlNC W EACH SPEC/ES. Fig. 8 of cold at a given humidity may be absolutely unable to stand that same temperature at another degree of saturation or relative humidity. Our absolutely fatal temperatures tlierefore will form some sort of a zone on our chart and this zone will probably be bounded by a curve. We call tlie temperatures below this curve the LOWER ZONE OF FATAL TEMPERATURES. Death caused by cold is called RHIGO- PLEGIA. Slightly above these absolutely fatal temperatures will be a zone of temperatures which might cause death if experienced sufficiently long, but which at least cause a complete suspension of all activity. And still higher will be temperatures which also cause suspension of activity, but which do not cause death even when experienced for very long pe- RELATIONS OF CLIMATE AND LIFE 99 riods. Formerly, this suspension of activity by animal life on account of cold was called hibernation, which means winter rest. The writer has shown (Pierce, W. D., 1916, Joum. Agr. Res., vol. 5, pp. 1183-1191) that this same inactivity may be caused by dryness or heat and possibly by excessive humidity, and that a creature may remain in the same state of inactivity from the heat of summer tlirough the cold of winter and be awakened from it only by the addition of a requisite amount of moisture at effective temperatures. We must seek other terms than hibernation, or winter rest, and aestivation, or summer rest. As this rest consists essentially of an almost complete cessation of all bodily functions, and is a state of insensibility, we may very properly designate the so-called hibernation as RHIGANESTHESIA, or insensibility due to cold. This state may be acquired naturally as winter sets in, or may be artificially induced at any time of the year by lowering the tempera- ture. The temperatures inducing RHIGANESTHESIA are grouped into the LOWER ZONE OF INACTIVITY, or the ZONE OF RHIG- ANESTHESIA. As the temperatures increase, a creature in the state of rest or rhiganesthesia, commences to show slow movements of the body fluids, and slight jerky motions, which increase with increase of temperature. This awakening or anastasis, when caused by temperature change, is a THERMANASTASIS. The approximate point at any given humidity at which thermanastasis begins is the ZERO OF EFFECTIVE TEMPERATURE. It must be firmly fixed in your minds that there is not a single zero of effective temperature, as so often claimed, but a different one for every degree or portion of a degree of relative humidity. In other words, at one humidity the awakening may occur at one temperature, and under other conditions of humidity the temperature ma}' be considerably higher or loAver. These points can be connected by a curve which repi'esents the lower limit of the ZONE OF ACTIVITY, or the THERiNIOPRACTIC ZONE, mean- ing a zone of effective temperatures. Many authors have manifested considerable confusion in their writ- ings and have even claimed that other authors were incorrect because a certain developmental period or reaction was accomplished in their ex- periments at a given temperature in a certain period of time while the other investigators obtained totally different results. A man working in a moist coastal section could not justly compare his results with those of a man working in a drier section unless the conditions of humidity were recorded also. For this reason, the writer has maintained that labora- tories attempting to correlate temperature with life history, must at least be equipped with maximum and minimum thermometers and a sling psychrometer for determining humidity, and that accurate results are 100 SANITARY ENTOMOLOGY based only on a recording liygrothermograph, checked by the above mentioned instruments. The great bulk of work naturally is upon the reactions which take place in the zone of activity. It must not be forgotten, however, that control work depends often upon a correct knowledge of the lower zone of fatal temperatures, and that successful storage of breeding material, until the investigator is ready to use it, depends often upon a knowledge of the requirements of rhiganesthesia. Following the awakening, the body takes up all its natural functions and we must assume that sustenance is available. The first activities, at temperatures just above the zero of activity, are naturally very sluggish and this state of sluggisliness may be kno^\^l as RHIGO- NOCHELIA, or sluggishness caused by cold. Some creatures are very sensitive to cold, usuall}' when the humidity is high. Pain produced by the application of cold is called CRYAL- GESIA. An abnormal sensitiveness to cold is known as CRYESTHESIA, and a morbid sensitiveness as HYPERCRYALGESIA. These sensa- tions are probably only experienced with a descent of temperatures. In the zone of effective temperatures or thermopractic zone there is a point or a small restricted zone of temperatures at which all activi- ties are most effective, that is, the greatest amount of work is accom- plished with the least amount of exertion and the least loss of energy. This is the so-called OPTIMUM, or perhaps better, PRACTICOTATUM, meaning most effective. As temperatures ascend to the practicotatum any given function is performed in proportionately shorter time. As. the temperatures ascend above the practicotatum a particular function may be exercised more rapidly but less accurately or less effectively, as for instance, more eggs may be laid but fewer hatch : but the activity is feverish and soon exhaustion takes place, or the individual gradually becomes more stupid and sluggish. This heat sluggishness is therefore called THERMONOCHELIA. Different reactions to heat may be experienced and these have all received appropriate designations. As for example, a stifling sensation is called THERMOPNIGIA ; an unusual sensibility to heat THERMAL- GESIA, and a more intense sensibility HYPERTHERMALGESIA. The ability to recognize changes of temperature is THER^IESTHESIA, and its extreme is designated as THERMOHYPERESTHESIA, an abnormal sensitiveness to heat stimuli. A fondness for heat or requiring great heat for growth is called THER^NIOPJ' .1.IC, while resistance to heat is called THERMOPHYLIC. When a stifimg temperature is ex- perienced rapid breathing or THERMOPOLYPNEA is often experi- enced. Contraction under the action of heat is designated as THER- RELATIONS OF CLIMATE AND LIFE 101 MOSYSTALTIC. The adaptation of the Isody temperature to that of the environment is PECILOTHERMAL. A morbid dread of heat is THERMOPHOBIA. The determination of the direction or rate »f locomotion by heat is called THERINIOTAXIS and movement brought about by heat is THERMOTROPISM. As the temperatures increase sluggishness increases until sleep or inactivity is induced and this condition once known as aestivation or summer rest may better be known as THERMANESTHESIA or insensi- bility caused by heat. The point at which anesthesia begins at any given hamidity is the upper boundary of the thermopractic or effective zone. Phose tempera- tures at which successful Thermanesthesia may be experienced embrace the UPPER ZONE OF INACTIVITY, or the ZONE OF THERM- ANESTHESIA. This quickly merges into those high temperatures which may with sufficient duration of time cause death, and finally, those tem- peratures which are absolutely fatal under all conditions. The highest zone is therefore the UPPER ZONE OF FATAL TEMPERATURES. Death from heat is known as THERMOPLEGIA, or heat stroke. Most investigators have stopped with a more or less hazy acknowledg- ment of the existence of these various zones of reactions on the ascend- ing scale of the thermometer, but the literature contains few references to similar zones of reactions on the scale of relative humidity, liowever, if we stop to think we must acknowledge that similar reactions do take place. We may have death from absolute dryness at almost any tempera- ture, in other words, we have a condition which is called APOXERAE- NOSIS, or drying up. At very low humidities one may become insensi- ble and thus we have XERANESTHESIA. Likewise, a little higher humidity induces sluggishness or a state of XERONOCHELIA. We have most of us experienced this condition of stupidity in a living room at normal temperatures in the winter due to lack of sufficient moisture. So also there is the humidity which enables each individual to accom- plish the greatest results in the least time with the least amount of exhaustion and this is the PRACTICOTATUM. With increase of humidity the activity lessens until an excessively humid atmosphere brings about HYGRONOCHELIA or sluggishness due to moisture; then HYGRANESTHESIA may be experienced by some species and finally death due to excessive moisture or HYGROPLEGIA. This makes it obvious therefore that when we plot the reactions of a species to temperavind and humidity, we are likely to find a series of closed figures delineating concentric zones of fatal, inactive, active and optimum conditions. Thus it is apparent that Rhigoplegia, Apoxeraenosis, Thermoplegia, and Hygroplegia form a single zone of loa SANITARY ENTOMOLOGY temperature-humidities which cause death — this whole zone is the fatal or OLETHRIC ZONE. All conditions of life lie within it, the next zone being that which includes Rhiganesthesia, Xeranesthesia, Thermanes- thesia, and H^'granesthesia ; the whole zone therefore being the ANES- THETIC ZONE, or zone of rest, which includes the conditions known as hibernation and aestivation. Within this is the THERMOPRACTIC ZONE or zone of effective temperatures, which is naturall}^ made up of sub-zones representing degrees of activity, as the NOCHELIC SUB- ZONE of sluggish activities on the outside and the PRACTICOTATUM at the center. : ,^^ '^1 5UCCESTCD cums Of M m?OHiis OF Amku mmuNi to hujiio TEMPERATURES WITH C£RWI« /ICTWi RfCORDS i£W/«C /IS /I BASIS. Fig. 9 Temperature and humidity affect every bodily function of every creature of the plant and animal kingdom. Some creatures may love cold, some heat, some dryness, some moisture. The pattern of their reactions will therefore shift from one place to another on the chart. Some creatures may be so resistant to cold that fatal temperatures are never nonnally experienced and rarely artificially. Some may be very resistant to dryness and others capable of standing an}^ degree of hu- midity. In case of plants the root system receives one set of stimuli and the upper portion another, so that the interpretation is not as simple as with animals. In the different stages of growth a creature may have different abil- ity to withstand extremes. If the approach to unfavorable or noneffective conditions is gradual, i RELATIONS OF CLIMATE AND LIFE 103 the body gradually adjusts and adapts itself for entrance into a dormant state. We find adaptations against cold, heat and dryness, often in cysts or in cases constructed by the creature, and in fact some of these protective cases are made of substances impervious to water. In the state of encystment far greater extremes can be experienced than in the normal state, because of the impervious nature of the cyst. Successful dormancy often depends upon the rapidity with which it was brought about. Most creatures practically free the intestinal canal before entering a resting stage. A sudden lowering or raising of temperature may be fatal at tem- peratures which would normally be easily withstood if approached grad- ually. Alternation of high and low temperatures, if sudden, is often fatal at normally effective temperatures. A creature may become dormant with descending temperatures at a higher temperature than it would awaken with ascending temperatures. A continuous maintenance of an even temperature and humidity is more or less enervating. A climate which has sufficient variation to allow certain periods of rest from cold at night and heat in the day is probably productive of better results. It is possible in a given day for a creature to have two active and two dormant periods. As for example, observations of many insects will show that they sleep during the cold parts of a night, are active during the morning, sleep during the hottest part of the day, are again active in the evening and early parts of the night. It is also noticeable that on humid days many in- sects are inactive but as soon as the air dries they again resume activ- ity, and the reverse is found in arid regions. Many investigators have failed in keeping insects alive for experi- ment because of failure to keep sufficient water present for drinking purposes and maintenance of proper humidity. As long as any creature is experiencing effective temperatures it must have food available to take when needed and this food must be in proper condition. Long periods without food at noneffective tempera- tures can be experienced, but at effective temperatures the length of life is relatively short. This is a very important point in control work with all insects. If you can deprive them of food for a sufficient period when the climatic conditions enforce activity, then control is easy. There are many very difficult points in this question. Inasmuch as noneffective temperatures and also noneffective humidities may be experienced each day, it becomes necessary to make elaborate studies to ascertain the boundaries of the thermopractic and hygropractic zones, and only a thermo-hygrograph record sheet will enable one to make any kind of a satisfactory study. 104 SANITARY ENTOMOLOGY There is a rule which receives much support, that a given reaction or stage of development is accomplished at an almost constant total effective temperature, which is the multiple of time units by temperature units accumulated above the zero of effective temperature. Since the zero varies with the humidity, the total effective temperature obtained by this rule does likewise. We must therefore reword the rule to read: A given reaction or stage of developvient is accomplished at any given mean humidity at a constant total effective temperature, which is the mvltiple of effective time units by temperature u/nits accumulated within the zone of effective temperatures at a given atmospheric pressure. To compute this one* must first eliminate all tim'" temperature, and humidity which was noneffective, whether at the top or bottom of the scale. For instance, if at 60% humidity the temperatures 63° to 85° are effective, and during the day the temperature ranged from 50° to 90°, but only during eight hours at the effective temperatures ; we must multiply the period 8 hours by the mean temperature experienced be- tween 65° and 85°, considering 65 as and 85 as 20. The result is the total effective temperature of that day. Adding these total effective temperatures during the total period of the stage, we obtain the total effective temperature necessary to bring about the perfection of the stage. Necessarily this is a very complicated proposition, requiring very careful computations. Nevertheless, once worked out we can es- tablish laws of control which are of utmost value. Some of the following lectures will refer to the principles laid dow^l in this lecture and lines of research will be suggested leading toward control measures. The charts (figs. 8, 9) should be studied in connec- tion with the lecture. CHAPTER VII Diseases Borne by Non-Biting Flies -^ W. Dxvight Pierce It will be necefjjSary in discussing the role of flies in the transmission, of disease to divide the flies into several categories, because so many species of the order Diptera are involved. The flies can be divided into two large groups, those which bite and those which do not bite, but, rather, sip their food. Two excellent monographs on the relations of flies and disease have been publislied, that on the non-bloodsuckers by Graham-Smith, and that on the bloodsuckers by Hindle. This lecture deals with the non-biting flies only. Among these flies are to be found the principal house-visiting flics, foremost among which is the house or typhoid fly, Musca domestica Linnaeus, followed by the blue bottle blow flies, Calliphora vomitoria Linnaeus and C. erythro- cephala Meigen, the green bottle blow fly Liicilia caesar Linnaeus, and various other species. The mouth parts of these flies are constructed onl}^ for sucking or sipping liquid or semi-liquid foods. In this lecture can only be given a very condensed statement of the relationship of these flies to disease. A more extensive study should involve the reading of the books by Hewitt and Graham-Smith quoted in the bibliography. In these volumes the evidence is given in great detail. Among the most striking of the investigations into the capacity of non-biting flies for the carriage of disease germs, are a series of three excellent papers by the Italian investigator, Cao, whose work is over- looked by many subsequent writers. In fact, there has been but one good rcvicAV of his results in English. And yet his investigations opened up the way for practically all of the work on bacterial transmission by insects. Working with larvae and adults of 3Iusca domestica Linnaeus, Calliphora vomitoria Linnaeus, Lucilia caesar Linnaeus and Sarcophaga carnaria Linnaeus, he proved that the larvae of these flics could take up and pass through their intestines any bacteria occurring in their food, and that all four species acted exactly alike in this regard. Except where he specifically stated, his results applied to all four species in *This lecture was presented in two parts on July 8 and 15 and distributed entire on July 15, 1918. It has been revised for this edition. 105 106 SANITARY ENTOMOLOGY every instance. Step by step, he proved tliat ftj-hu'vce take up bacteria from th.cir food, and xclien breeding in iiesh ma/j take up disease germs as well as non-pathogenic germs; that these germs may pass unaltered through the insects' intestines and out in their feces; that some of them may remain for a long period in the intestinal caned, and some even may midtiply therein; that they may be taken up by the larva and per- sist through its metamorphosis until it arrives at the adidt stage, and for days thereafter, and may be carried by this adult and deposited with its feces on food or excrement ; and that these bacteria will also be found in the glutinous substances surrounding the eggs ivhen deposited, and thus contaminate the substance in rvhich the nexcly born larvae mil feed; and of course be taken up by this second generation and possibly be distributed farther by it. These facts were worked out by Cao in 1905 and 1906, and 3^et Graham-Smith credits Faichnie (who worked in India in 1909) with be- ing the first one to suggest that bacteria ingested by the larva might survive the pupal stage and be present in the intestine of the adult. Later, Bacot, and also Ledingham in 1911 and Graham-Smith in 1912, corroborated these claims that the bacteria could persist in the body throughout the metamorphosis. Ledingham (1911), Nicholls (1912), and Graham-Smith (1912) have shown that the fly larvae have great powers of destroying micro- organisms due to the fact that many of these organisms are not adapted to the conditions prevailing in the interior of the lar\^a and pupa, or perhaps more correctly due to the hostile action of bacteria which more normally frequent the intestines of the larvae. These normal inhabitants of the fly intestine are principally non-lactose fermenting organisms. Not only bacteria but also protozoa, such as the amoebae of dysen- tery, and the eggs of parasitic worms, may be taken up by the fly larvae or adults and deposited in the feces. Roubaud (1918) has brought out the fact that multitudes of the amoebic dysentery germs taken up by adult flies and deposited in their feces die because of the rapid drying of the feces, and he credits the fly with being a great agent in the de- struction of multitudes of protozoa, while granting the equally great opportunity of the fly to contaminate food therewith. Stiles in 1889 fed larvae of Musca domestica with female Ascaris lumbricoides, which they devoured, together with the eggs they con- tained. The larvae as well as the adult flies contained the eggs of Ascaris (Nuttall, 1899, p. 39). NicoU (1911) has very thoroughly in- vestigated the relationships of flies to the possible carriage of eggs of worms and demonstrated the ability of adult flies to ingest the eggs of various species of worm.5, provided these are small enough, and to pass DISEASES BORNE BY NON-BITING FLIES 107 them out whole m the feces, but in all his experiments with the larvae he found that the eggs were crushed. In addition to tlie ability of flies to carry disease germs in their body, there are multitudes of proofs of their ability to carry them also on their body and to deposit them when they feed. The transmission of disease hy non-hlood sucking flies is exclusively hy contamination either of food, water or wounds. Most of the flies which frequent houses and food or visit man because of attractive secre- tions or injuries also are attracted to and breed in excreta or garbage. Hence the contamination of food by direct transportation from infected excreta is a very simple matter. This contamination may be by the simple depositing of disease germs carried on the body of the flies, or by regurgitation, or the deposition of feces. Wherever a fly alights and remains a few minutes it deposits either vomit or feces. By the nature of its breeding it is hardly to be expected that these deposits will not contain some kind of bacteria, and possibly^ protozoa or worm eggs. If these deposits are made on the moist media off'ered by foods the germs may easily retain their virulence until eaten. As flies can travel considerable distances, at least thirteen miles, the existence of a single disease case with insanitary conditions in the vicinity enabling fly breedimg, might easily infect an entire city or army camp if the flies were permitted to reach the food of the inhabitants. It is because of the total lack of sanitary waste disposal in country dis- tricts that diseases like typhoid fever and dysentery usually become very widespread. We can not know the source of the -flies which enter our houses. We must not let them visit our food. They must be kept away from the eyes and mouths of babies. Our markets where meats and vegetables are sold must be better protected. Only througli influencing public opinion will we be able to have the fly nuisance in our own public markets abated. Food offered for sale shoidd be kept under glass or screen at all times. There are so many organisms transmitted by the non-blood-sucking flies that we shall have to deal with them rather briefly and preferably according to their classification. A thorough digest of the mass of matter submitted below should impress the readers with the necessity of fly prevention. PLANT ORGANISMS CARRIED BY NON-BITING FLIES Thallophyta: Fungi: Schizomycetes: Coccaceae Streptococcus equinus Andrewes and Horder, a non-pathogenic organ- ism found in horse dung, was found by Torrey (1912) in a number of cases on the surface of city caught flies. 108 SANITARY ENTOMOLOGY Streptococcus fecalis Andrewes and Horder, an organism occurring normally in the human intestine and occasionally pathogenic has been isolated from city caught Musca domestica by Scott (1917), Cox, Lewis and Glynn (1912) and Torrey (1912). Streptococcus pyogenes Rosenbach, an organism causing ERYSIPE- LAS, SUPPURATION and SEPTICAEMIA was isolated by Scott (1917) from city caught Musca domestica in Washington. Streptococcus salivarius Andrewes and Horder, an organism fre- quently found in the mouth, but rarely pathogenic, has been isolated from the intestines of city caught Musca domestica by Torrey (1912), and was also found on flies by Cox, Lewis and Glynn (1912). Diplococcus gonorrhoeae Neisser (Gonococcus), the cause of GONOR- RHOEA, was found b}^ Welander (1896) carried on the feet of a fly for three hours after they had been soiled with secretion. Diplococcus intraceUularis meningitidis Weichselbaum {Meningococ- cus), the cause of CEREBROSPINAL MENINGITIS, is thought to be possibly carried by flies by MacGregor (1917). Micrococcus pavus was isolated by Torrey (1912) from the intes- tinal content as well as the surface of city caught flies. Micrococcus tetragenus Gaff'ky, commonly found in the human body, sometimes pathogenic, sometimes saprophytic, was isolated from Musca domestica by Scott (1917). Staphylococcus pyogenes alhus Rosenbach, a cause of SEPTICAE- MIA, was isolated by Cao (1906B) from the mucilaginous envelope cov- ering the eggs of Musca domestica, Sarcophaga vomitoria, Lucilia caesar and Calliphora vomitoria at the time of deposition. Scott (1917) iso- lated it from the bodies of Musca domestica. Staphylococcus pyogenes aureus Rosenbach, a frequent cause of ABSCESSES, etc., was shown by Celli (1888) to retain its viinilence after passing through the flies' intestines. Herms (1915) proved by experi- ment that Musca domestica can carry great numbers of this organism on its feet. Torrey (1912) and Scott (1917) isolated it from the bodies of city caught flies. Cao (1906B) isolated it from the eggs at the time of deposition of laboratory caught flies of Musca domestica, Calliphora vomitoria, Sarcophaga camaria and Lucilia caesar. Staphylococcus pyogenes citreus Passet, a pathogenic, chromogenic, pus-forming organism, was isolated by Scott (1917) from bodies of house flies Musca domestica in Washington. Cao (1906B) fed larA'ae of Musca domestica, Sarcophaga camaria, Calliphora vomitoria, and Lucilia caesar on m'cat polluted with this organism and recovered it from the feces of mature flies bred from these larvae. Sarcina aurantiaca Lindner and Koch, a zymogenic, chromogenic (orange yellow) organism found in air and water, rarely pathogenic, DISEASES BORNE BY NON-BITING FLIES 109 was found by Cao (1906B) to be capable of passing through the intes- tines of larvae of Musca domestica, CalUphora vomitoria, Sarcophaga car- naria, and Lucilia caesar, in all stages of larval growth and of remaining in the body through pupation to maturity. Thallo'phyta: Fungi: Schizomycetes: Bacteriaceoe Bacillus of Koch- Weeks, the cause of an acute infectious CONJUNC- TIVITIS (pink eye), is thought by Castellani and Chalmers (1913, p. 700) to be frequently carried by the little Oscinid gnat, Microneurum funicola Meijere, which causes great annoyance by hovering in front of the eyes and attacking the eyes and ears. The flies may be driven away by the odor of Odol. Bacillus A of Ledingham, a nonlactose fermenter from the feces of children, has been found by Tebbutt (1912) to be normal to the house fly, Musca domestica, being found on the ova, and in the larva?, pupae and adults, and when fed to the larvae survived tlirough the metamorphosis to the adult stage. Bacillus of Morgan, which is frequently found in cases of INFAN- TILE DIARRHEA, has been found in various strains commonly in the intestines of Musca domestica by Nicoll (1911), INIorgan and Ledingham (1909), Cox, Lewis and Glynn (1912) and Graham-Smith (1912), and the latter found that when fed to larv.T of the house fly it could survive through the metamorphosis to the adult fly. Bacillus acidi lactici Hueppe, a bacillus common to cows' milk, has been isolated from tlie bodies and from the intestinal contents of Musca domestica in New York, Washington, London and Liverpool by Torrey (1912), Scott (1917), Nicoll (1911), and Cox, Lewis and Glynn (1912). Bacillus aerogenes capsidatus Welch and Nuttall is a pathogenic organism gaining entrance to the body chiefly through wounds and caus- ing severe infections resulting often in GANGRENE. In the surgery of the Great War this organism has been a very important one. It occurs as a normal inhabitant of the intestine of man and some of the animals. It has been isolated by Torrey (1912) from the surface as well as the intestinal contents of city caught flies. Bacterium anthracis Davaine, the cause of ANTHRAX, although probably more often carried by biting flies, has been shown by Davaine (1870) to be capable of cai-riage by CalUphora vomitoria. He fed flies on anthracic blood and inoculated guinea pigs with parts of these flies 40 hours to 3 days later, obtaining fatal results in 4 out of 7 cases. From flies of CalUphora vomitoria caught in his laborator}' Cao (1906B) isolated virulent germs of B. anthracis adhering to the glutinous secretion surrounding the eggs as they were deposited. He later placed on flesh 110 SANITARY ENTOMOLOGY of animals dead from anthrax externally sterilized eggs of Musca domestica, CalUphora vomitoria, LucUia ccesar and Sarcophaga camaria and from day to day dissected the larvae feeding on this flesh, always demonstrating anthrax germs in their bodies, and he further proved that these larvae retained the germs in their bodies through pupation to maturity and for at least nine days after maturity. He fed flies on meat polluted with anthrax and demonstrated twenty-four hours later the bacilli in the feces and on the eggs. Graham-Smith (1912) found that many blow flies (Calliphora erythrocephala and Lucilia ccesar) which emerged from larvje fed on meat infected with anthrax spores were infected and remained so for 15 days or more. He also found that a large proportion of house flies (Musca domestica) which develop from larvae fed on spores of B. anthracis are infected. Because of the habit of blow flies of breeding in and attacking wounds there have been many cases of human anthrax on the battle front in Europe. The ease with which this may occur is quite evident in view of the above quoted investigations. Bacillus cloacfls Jordan has been found in the alimentary canal of Musca domestica in London by Nicoll (1911). Bacillus coli Escherich, an organism normally found in the alimentary canal of man, but often found causing secondary infections, was found by Cao (1906B) in various strains adhering to the eggs at the time of oviposition of flies caught in the laboratory (Musca domestica, Sarco- phaga camaria, Lucilia casar, and Calliphora vomitoria). Bacillus coli anaerogenes was isolated by Scott (1917) from Musca domestica caught in Washington. Bacillus coli communior Dunham, an abundant inhabitant of the human and animal intestine, has been isolated from the body and intes- tinal contents of Musca domestica in New York and Washington by Torrey (1912) and Scott (1917). Bacillus coli communis Escherich, an organism common in the intes- tine of man and animals and associated with a large variety of lesions, has been isolated from the body and intestinal contents of Musca domestica by Torrey (1912), Nicoll (1911), Scott (1917) and Cox, Lewis and Glynn (1912). Bacillus coli mutabilis was found on the body and in the intestines of Musca domestica in London by Nicoll (1911). Bacillus "colisimile'" Cao was fed by Cao (1906B) to larvae of Musca domestica, Calliphora vomitoria, Lucilia ccesar and Sarcophaga carnaria in flesh and he later demonstrated its abundant presence in the feces of the larvae. Bacillus cuniculicida Koch and Gaff'ky, the cause of SEPTICEMIA in rabbits and guinea pigs, was isolated by Scott (1917) from house flies (Musca domestica) caught in Washington, and he looks upon the fly DISEASES BORNE BY NOxN-BITING FLIES 111 as the carrier of laboratory epidemics of rabbit and guinea pig septicaemia experienced for several years. Bacillus diphtheria; Klcbs, the cause of DIPHTHERIA, according to experiments performed by Graham-Smith (1910) may be taken up by flies feeding on infected saliva or sputum and may live in the crop and intes- tines of the fly for over 24 hours, and in fact in one experiment he twice recovered it from the feces of flies 51 hours after feeding on bacilli emulsi- fied in broth. Bacillus clyseniericE "F" Hiss and Russell, one of the organisms found in DYSENTERY and INFANTILE DYSENTERIC DIARRHEA, was experimented with by Tebbutt (1913) who fed, it with blood to larvae of Musca domestica. The eggs from which these larvae were hatched were washed in weak carbolic acid or lysol to disinfect them. Before feeding the larvae on the organism they were carefully washed in weak lysol solution. In a limited number of cases the bacillus was recovered from the pupae and adults of larvse thus fed. The Shiga bacillus, Flexner bacillus and parabacillus of dysentery were all isolated on flies in Macedonia and a decided correlation between the incidence of flies and dysentery was established by Col. Dudgeon (1919) and associates. They found the examination of fly feces the most suitable method for the isolation of dysentery bacilli. Bacillus enteriiidis Gaertner, the cause of FOOD POISONING in man, and epizootic diseases among animals, was experimented with by Graham-Smith (1912), who fed it to the larvae of Calliphora erythro- cephala and Musca domestica, but did not recover it in the adults matured from these larvae. Cox, Lewis and Glynn (1912) isolated a similar bacillus from flies cauglit in Liverpool. Bacillus feccdis alkcdigenes Petruschky, a not infrequent inhabitant of the human intestine, which has been associated with a case of severe gastroenteritis, was isolated by Torrey (1912) from the intestinal con- tent of city caught flies in two different instances. Bacillus ^uorescens liqu^aciens Fluegge, a common organism found in water and air, was fed by Cao (1906B) to larvje of Musca domestica, Calliphora vomitoria, Lucilia casar, and Sarcophaga carnaria, on flesh containing the organisms, and found among the predominant bacteria in the feces of the larvae. He found that this organism taken up by the larvae could persist through the pupal stage and be obtained from the feces of flies immediately after their emergence, and when fed to adults it was demonstrated on their eggs when deposited. Bacillus fluorescens nonliquefaciens Eisenberg and Krueger, found in water and in butter, was fed by Cao (1906B) to larva; of Musca domestica, Ccdliphora vomitoria, Lucilia avsar, and Sarcophaga carnaria, and later demonstrated in the feces of the larvae. 112 SANITARY ENTOMOLOGY Bacillus gasoformans nonliquefaciens was found on the body and in the alimentary canal of Musca domestica caught m London by NicoU (1911). . . , Bacillus griinthal was found on the body and m the intestines of Musca doinestica hy 'NicoW (1911). ^ Bacillus lactis acidi Marpmann, a zymogenic bacillus found in cows milk, was isolated by Torrey (1912) from the surface of city caught flies. Bacillus lactis aerogenes Escherich, which is almost constantly found in milk and is one of the chief causes of souring of milk, was isolated from flies by Cox, Lewis and Glynn (1912). Bacillus lepra; Hanson, cause of LEPROSY, may be carried by Musca domestica, according to Leboeuf (1913). Bacillus mallei Loffler and Shutz may be transmitted by flies according to Rosenau (1916). Bacillus neapolitanus has been found on the body of Musca domestica by Nicoll (1911) and Cox, Lewis and Glynn (1912). Bacillus oxytocus perniciosus Wyssokowitsch, a pathogenic organism found in milk, has been isolated from the intestines of Musca domestica by Nicoll (1911). Bacillus paracoli Duval and Schorer, a pathogenic organism found frequently in the stools of children suffering from summer diarrhea, has been isolated several times by Torrey (1912) in New York, both from the surface and intestines of city caught flies. Bacillus paratypliosus "A" Schottmuller, cause of PARATYPHOID A fever was isolated from the intestinal contents of city caught flies by Torrey (1912). Bacillus paratypliosus "B" Schottmuller, cause of PARATYPHOID B fever, was recovered from the body and intestines of Musca domestica caught in London by Nicoll (1911), with the evidence that it had been carried by the flies at least for 11 days. Bacillus pestis Kitasato, the cause of BUBONIC PLAGUE, although normally carried by fleas, has been shown by Yersin (1894) and Nuttall (1897) capable of remaining in the intestines of flies in a virulent condi- tion for at least 48 hours after infection. Nuttall's experiments indicated that this bacillus is fatal to Musca domestica. Bacillus prodigiosus Ehrenberg, a nonpathogenic, zymogenic, and chromogenic organism, was fed by Cao (1906B) to adult flies of Musca domestica, Calliphora vomitoria, Lucilia casar, and Sarcophaga carnana and was demonstrated in their feces and on their eggs 24 hours later. Larvffi fed on polluted meat contained the germs in their bodies and carried them through pupation and they could be demonstrated in the intestines of the adult up to nine days after emergence. Ledingham (1911) corroborated Cao's findings of the persistance of this bacillus DISEASES BORNE BY NON-BITING FLIES 113 throughout the metamorphosis of Musca domestica. Graham-Smith (1913) found that flies of Musca do^nestica fed on this bacillus may infect milk for several days, while CaUiphora vomitoria flies when infected con- stantly produced infection in milk up to the eighth day and in syrup up to the twenty-ninth day. Bacillus proteus vidgaris Hauser, B. p. mirahilis Hauser, and B. p. zenJceri were fed by Cao (1906B) to larvje of Musca domestica, CaUiphora vomitoria, Sarcophaga carnaria, and Lucilia casar, and were found abundantly in the feces of the larvae so fed. Species of Proteus were also found deposited with the eggs of flies fed on infected flesh. Bacillus proteus vulgaris was isolated by Scott (1917) from Musca domestica caught in Washington. Bacillus pyocyaneus Gessard associated with SUPPURATING WOUNDS in which blue-green pus is present was isolated in two strains from flies caught in Liverpool by Cox, Lewis and Glynn (1912). Bacot and Ledingham (1911) by carefully controlled experiments have proved that the larvfe of Musca domestica fed on infected food retain this bacillus in the gut through the metamorphosis to the adult stage and ma}' dis- tribute it in their excreta. Bacillus radiciformis TatarofF, a saprophytic organism found in water, was fed b}' Cao (1906B) to larvje of Musca domestica, CaUiphora vomitoria, Lucilia casar and Sarcophaga carnaria, and recovered from the feces of the larvse. Bacillus ruber K-ielensis Breunig, a chromoparous (I'cd) bacillus found in water at Kiel, was fed by Cao (1906B) to larvae of Musca domestica, Sarcophaga carnaria, CaUiphora vomitoria, and Lucilia ccesar, and he demonstrated that the larvs could take it up in all stages of growth, and that the bacilli persisted in their bodies through pupation to maturity. Bacillus schafferi Freudenreich, a nonpathogenic, zymogenic organism, found in "puff"y" and "Nissler" cheese, has been found by Nicoll (1911) in London on the body and in the intestines of Musca domestica. Bacillus septicus agrigenus Nicolaier, a pathogenic organism, was fed by Marpmann (1897) to flies, and 12 hours later the contents of the flies were inoculated into mice, producing fatal infection in a large per cent of the inoculations (Nuttall 1899). Bacillus "similcarbonchio" Cao, a pathogenic organism similar to Bacillus anthracis, which produces CARBUNCLES when inoculated, was fed by Cao (1906B) to larvae of Musca domestica, CaUiphora vomitoria, Lucilia caesar and Sarcophaga carnaria and isolated from the feces of the larvae in a very virulent strain. In examinations of many flies cauglit in the laboratory he occasionally isolated a non-pathogenic, mobile strain of this organism. Bacillus subtilis Ehrenberg, an organism frequently found in air,, 114 SANITARY ENTOMOLOGY water, and soil, and seldom pathogenic, was fed by Cao (1906B) to larva? of Musca domestica, Calliphora vomitoria, Lucilia cwsar and Sarcophaga carnaria and was among the predominant bacteria recovered from the feces of the larvfe. Bacillus suipestifer Salmon and Smith, often found in cases of FOOD POISONING and SUMMER DIARRHEA, is recorded by Scott (1917) from the house fly, Musca domestica. Bacillus '^tifosimile'" Cao, a pathogenic organism strongly resembling B. typhosus, was fed by Cao (1906B) to larvae of Musca domestica, Calliphora vomitoria, Lucilia ccesar, and Sarcophaga carnaria and later demonstrated in the feces of the larvae as among the predominant forms in strains of differing virulence. From flies caught around the laboratory he isolated pathogenic strains adhering to the eggs when deposited. Bacillus tuhercidosis Koch, the cause of TUBERCULOSIS, was found in four out of six flies caught by Hofmann (1888) in the room of a tuber- culosis patient, whose sputum had contained many germs. Flies fed artificially with sputum died in a few days. Within twenty-four hours of their being fed on the sputum, the tubercle bacilli appeared in their excreta. A guinea pig inoculated with the intestines of flies developed tuberculosis. Celli (1888) reports Alessi's experiments of inoculating the feces of flies fed on tubercular sputum, and causing the development of tuberculosis in two rabbits. Spillman and Haushalter (1887) were, however, the first to find the tubercle bacilli in the intestines and feces of flies which had fed on sputum. Bacterium tularcnse McCoy and Chapin, cause of a fatal RODENT PLAGUE of which a few human cases are on record, may be transmitted by Musca domestica. Wayson (1915) inoculated the crushed bodies of flies fed on the viscera of an animal dead 48 hours and obtained fatal results in three series of experiments with guinea pigs. Bacillus typhosus Eberth, the cause of TYPHOID FEVER, was first shown by Celli (1888) to be capable of passing through the intestines and into the feces of flies. Many authors have added proofs of the role of the fly in the transmission of this disease and these are ably summarized by Graham-Smith (1913) and Hewitt (1914). Faichnie (1909) proved that flies could carry this bacillus in their intestines for 16 days. Leding- ham has isolated the bacillus from the intestines of Musca domestica which had fed on it in the larval stage, but found that the normal bacilli in the larval intestines usually prevent its successful survival through meta- morphosis. Bacillus vesiculosus, which is very frequently found in human excre- ment, was found on the body of Musca domestica caught in London by Nicoll (1911). Bacillus xerosis Kutschert and Neisser, a presumably nonpathogenic DISEASES BORNE BY NON-BITING FLIES 115 organism, usually found in the eyes, and often associated with conjunc- tivitis, was isolated by Torrey (1912) on the surface of city caught flies. Tliallopliyta: Fungi: Schizomycetes: Spirillaceae Spirillum (Vibrio) cholera; Koch, the cause of ASIATIC CHOLERA, may be carried by flies. The connection of flies with the prevalence of cholera was first noted by Nicholas (1873). Maddox (1885) first per- formed experiments with Calliphora vomitoria Linnaeus and Eristalis tenax Linnaeus as well as other insects and determined microscopically the presence of the motile cholera vibrios in the feces. Tizzoni and Cattoni (1886) caught flies in cholera wards and after several hours obtained characteristic cultures of the organism. Many other authors, as Sawtchenko (1892), Simmonds (1892), UfFelmann (1892), Macrae (1891<), have furnished proofs of fly dissemination of the cholera vibrio, a summary of which can be found in the books by Graham-Smith and Hewitt. SUMMARY OF PLANT ORGANISMS A brief survey of the data presented above will perhaps help to imprint the gravity of the fly menace on all who read this. Sixty-three minute plant organisms have been shown to be transmissible by domestic flies. Forty-four of these organisms have been found on or in flies caught in cities or buildings, in other words, were naturally carried by so-called "wild flies." Among these forty-four organisms naturally carried by flies were several noiTiial inhabitants of milk, also various normal inhabitants of the human and of animal intestines, which could only be taken up from excrement. Some of these organisms are taken from eyes, some from sputum, some from decaying vegetable matter, others from dairy products. The fly containing such organisms betra3^s its habits. We find the organisms of conjunctivitis, infantile diarrhea, sour milk, gas gangrene, enteritis, guinea pig septicaemia, leprosy, paratyplioid A, and paraty- phoid B fevers, bubonic plague, green pus, food poisoning, tuberculosis, typhoid fever, anthrax, rodent plague, gonorrhea, abscesses, erysipelas, bacillary dysentery, and cholera, and possibly cerebrospinal meningitis, normally carried by flies which frequent our houses, visit our bodies and pollute our food with their excreta. We also find experimental evidence that these same flies can carry the organisms of diphtheria, gastroenter- itis, and other pathogenic conditions. In other words, it would seem that non-blood-sucking flies can carry any bacterial or coccal disease in which the organism may be reached by the fly on the body of the person, in his sputum, or his excreta, and undoubtedly the same is true of such diseases of animals. I 116 SANITARY ENTOMOLOGY It is of interest to note that in nineteen species the organism has been proven to pass freely through the intestinal canal of the larvae, in thirty- seven species through the intestines of the adult, and in eleven species to be capable of persisting in the larvje through metamorphosis to the adult. What greater argument could be found that flies are dangerous not only because of what they as flies have fed on, but also because of food they took while larvje, possibly a long distance away? We have not, however, gauged the depth of the fly's infamy, as we have so far only listed the evidence of plant diseases transmitted. DISEASES OF UNSETTLED ORIGIN PROBABLY CAUSED BY MICROORGANISMS PURULENT OPHTHALMIA is said to be carried by flies in Egypt. Brumpt accused Musca domestica of being a carrier of TRACHOMA. Rbsenau stated that flies have been found breeding in open lesions of SMALLPOX, and that flies may transmit MEASLES and SCARLET FEVER. Definite experiments certainly should be carried out with a view to determining the exact relationship of flies to these diseases, seek- ing first the possibility of transmission by fecal contamination. Howard and Clark (1912) found that Musca domestica flies can retain the virus of INFANTILE PARALYSIS or POLIOMYELITIS either in or on their bodies for 24 and 48 hours. The virus may remain alive in the body of the fly six hours after ingestion. The fly can obtain the virus from secretions of nose and throat and discharge of intestines. Very recently Dorset (1919) and associates have experimentally transmitted HOG CHOLERA by inoculating with crushed bodies of infected Musca domestica and Fajwia canicularts, and also by bringing such flies in contact with abraded surfaces. ANIMAL ORGANISMS CARRIED BY NON-BITING FLIES We will now consider in a similar manner the evidence of transmission of animal organisms by these same flies. Protozoa Sarcodina: Ainoehvna: Amoebidae Loschia coli (Losch) (Endamoeha) a supposedly harmless commensal in the alimentary canal of man, where it feeds on the contents of the bowels, may be carried in the encysted form by Musca domestica, accord- DISEASES BORNE BY NON-BITING FLIES 117 ing to Roubaud (1918), who finds that the cysts readily pass through the fly intestines at laboratory temperatures of 15-18° C. (59-65° F.) in 24 hours. It may be carried from ihfectcd stools to food but must be deposited in moist substances, as all cysts dry rapidly in dry fly feces. Ldschia histolytica (Schaudinn), the cause of AMOEBIC DYSEN- TERY, may be carried in the enc^^sted form by Musca domestica and CaUiphora erytlirocepliela according to Flu (1916). Roubaud (1918) has carefully investigated and finds that the free amoeba is quickly digested by the fly, but the cysts may pass readily through the intestines within 24 hours and may be demonstrated up to 40 hours. The cysts die rapidly in dry fly feces, and therefore to live must be placed on moist substances, or on food. Mastigophora: Protomonadina: Bodonidae ProwazeTiia sp. is found in Fannia canicularis (Dunkerly 1912). Mastigophora: Polymastigina : Polymastigidae Giardia intestinalis (Lambl) {Lamblia), the cause of LAMBLIAN DYSENTERY of rodents and man, may be carried in the encysted form by Musca domestica, according to Roubaud (1918), but must be deposited in the feces on moist substances, or directly on food. Mastigophora: Binucleata: Leptomonidae Crithidia calliphorae Swellengrebel is described as a parasite of CaUiphora erythrocephala Meigen. Crithidia muscae-dornesticae Werner is described as a parasite of Musca domestica Linnaeus. Leptomonas calliphorae (Swingle) is a parasite of CaUiphora erythro- cephala Meigen. Leptomonas drosophilae Chatton and Alilaire is a parasite of Drosophila confusa, • Leptomonas homalomyiae (Brug) is a parasite of Fannia scalojis Fabricius. Leptomonas lineata (Swingle) is a parasite of Sarcophaga sarraceniae Riley. Leptomonas luciliae (Strickland) is a parasite of Lucilia sp. Leptomonas luciliae (Roubaud) is described as a. parasite of Lucilia serenissima Walker. Leptomonas mesnili Roubaud is a parasite of Lucilia sp. 118 SANITARY ENTOMOLOGY Leptomonas muscae-domesticae (Burnett) is a parasite of Musca domestica Linnaeus, M. nebulo Fabricius, Fannia scalaris Fabricius, Pollenia rudis Robineau-Desvoidy, Teichomyza fusca Macquart, Lucilia sp., Pycnosoma puioriium Wiedemann, Scatophaga lutaria Fabricius, Neuroctena anilis Fallen, Homalomyia corviim Verrall, and Sarcophaga mums, undergoing complete metamorphosis in the bodies of the flics. Patton (1910) has demonstrated that the disease may be transmitted from fly to fly as follows : the food becomes infected from the feces of the infected flies which have fed on it ; uninfected flies may become in- fected by ingesting either the long flagellates, the short encysting forms, or the cysts, in the feces of other flies, or in food contaminated by other flies. Leptomonas pycnosomae Roubaud is a parasite of Pycnosoma putorium. Leptomonas roubaudi Chatton is a parasite in the Malpighian glands of Drosophila confusa Staeger. Leptomonas sarcophagae (Prowazek) is a parasite in the gut of Sarcophaga haemorrhoidalis Fuller and another species of Sarcoph- aga. Leptomonas soudanensis Roubaud is a parasite of Pycnosoma putorium. Leptomonas stratiomyiae (Fantham and Porter) is a parasite of Stratiomyia chameleon Linnaeus and S. potamida Meigen. Fantham and Porter (1916) proved it experimentally pathogenic by inoculation to Mus muscidus. Leishmania tropica (Wright), the cause of ORIENTAL SORE of man, may be taken up in the crithidial stage by Musca domestica and the organism demonstrated 48 hours after feeding, according to Carter (1909). According to Wenyon (1911) who investigated BAGDAD SORE, Musca domestica may readily feed on the sores and take up Leishmania, but there is no development of the organism and no parasites were found in the feces. On the other hand. Row, working with CAMBAY SORE believed the organism transmissible by Musca domestica up to three hours after the fly had fed on infected sores. He found the gut con- tents of flies infective for a monkey three hours after the fly had taken up Leishmania, but Patton (1912) maintains that Cambay sore never com- mences in a cut, scratch or abrasion, and failed to transmit the disease in this manner in numerous experiments with Musca nebulo and Musca sp. A new investigation, however, is warranted by Row's statement, seeking fecal infection of wounds. Rhynchoidomonas luciliae Patton is parasitic in the Malpighian tubules of Musca nebulo and Lucilia serenissima. DISEASES BORNE BY NON-BITING FLIES 119 Mastigophora: Binucleata: Trypanosomidae < Castellanella evansi (Steel) Chalmers (Trypanosoma) -, the cause of I SURRA, an African disease of horses and other mammals, may be carried by Musca domestica by contact with wounds. CasteUanella hippicum (Darling) Chalmers {Trypanosoma)^- the cause of MURRINA, a disease of horses and mules in the United States and Panama, may be carried according to Darling (1911, 1912) by Musca domestica, Chrysom3'a and Sarcophaga, from wounds by mechanical transmission. He ascertained that the trypanosomes remained alive in the proboscis of the fly at least two hours, and he also successfully inocu- lated a mouse with the crushed portions of a proboscis of a fly which had fed on infected blood. Isolation of tlie animals from fl}' attack, and bind- ing up of wounds wiped out the epidemic. He did not ascertain whether the trypanosome might pass out of the fly's feces and contaminate lesions in this manner, which naturally is the normal method of fly transmission. Mastigophora: Spirochaetacea: Spirochaetidae Treponema pertenue (Castellani), the cause of YAWS, an infectious disease of men, may be transmitted by the house fly, Musca domestica. Castellani in Ceylon (1907) found that flies eagerly crowd around the open sores of yaws patients. In the hospitals as soon as the dressings were removed from the yaws ulcerations, they became covered with flies, sucking with avidity the secretion, which they may afterward deposit in the same way on ordinary ulcers on other people. He conducted experi- ments which proved that the flies do take up the organism, which he recov- ered from the dissected mouth parts. He fed flies on the organism, then removed their appendages and fastened them over scarified areas of skin of monkeys, and obtained in two experiments positive lesions by this organism. Robertson (1908) also definitely obtained this spirochaete from flies collected on yaws lesions. Nicholls (1912) ascribes most of the cases of yaws in the West Indies to inoculation of surface injuries by Oscinis pallipes Loew. Sarcophaga is also considered a carrier. None of the experiments have been directed at obtaining infection through the deposition of the spirochaetes, taken up by the fly in feeding, in its feces on other ulcers or injuries. This would appear to be the most likely method of infection. ^ The classification of the Trypanosomes has recently been modified by Chalmers, including several genera composed of species with similar morphological and bio- logical characteristics. 120 SANITARY ENTOMOLOGY Neosporidia : Myxosporidia: Nosemidce Nosema apis Zander, a bee disease, may be communicated to Calliphora vomitoria and other insects through feeding on the bee excreta around beehives. Protozoa: Neosporidia: Myxosporidia: Thelohamdae Octosporea monospora Chatton and Krempf is a parasite of Fannia scalaris. Thelohania ovata Dunkerly is also a parasite of Fannia scalaris. HIGHER ORGANISMS CARRIED BY FLIES As pointed out in the introduction of this lecture, flies can carry the < eggs of higher organisms. The evidence is presented below, but refer- ence should be made to Dr. Ransom's lecture (Chapter V). Platyhelmia: Cestoidea: Cyclopliyllidea: Taeniidae Taenia {T aeniarhynclius) saginata Goeze, the FAT-TAPEWORM of cattle and rarely of man, has been commonly found in the egg stage in Musca domestica in British East Africa according to Shircore (1916). It is necessary that the eggs, passed in human or animal feces, reach the food or water of the next host (cattle). This may occur by means of insanitary sewage disposal, possibly under exceptional circumstances by the agency of flies. Platyhelmia: Cestoidea: Cyclopliyllidea: Hymenolepididae Choanotaenia infmidibulum (Bloch) Cohn, the FOWL TAPEWORM, developed to the cysticercoid stage in Musca domestica fed on the eggs, and Guberlet (1916) succeeded in infecting new-bom chicks by feeding them on infected Musca domestica. Davavnea cesticiUus Molin, a fowl tapeworm, was tested with negative results by Guberlet (1916), using Musca domestica and Calliphora vomi- toria in his search for the intermediate host. Davainea tetragona Molin, another chicken tapeworm, likewise gave Guberlet (1916) negative results with the same two species of flies. Platyhelmia: Trematoda: Malacotylea: Schistosomidae Schistosoma mansoni Sambon, the trematode worm causing intestinal Schistomiasis of man or BILHARZIOSIS, may be found in the egg stage DISEASES BORNE BY NON-BITING FLIES 121 in Musca domestica, according to Shircore (1916), who recorded eggs of this species in flies in British East Africa. The cercaria stage is passed in a snail. Nemathelminthes : Nematoda : Spiruridae Hahronema muscae (Carter) Diesing, a STOMACH WORM OF HORSES, passes its earlier stages in Musca domestica, according to Ran- som (1913). Either the egg or first-stage larva is ingested by the fly larva breeding in horse manure. Development goes on within the fly larva and pupa, the last stage being found in the proboscis of the adult ^y. It passes to horses through the swallowing of infested flies and probably may also leave tlie proboscis of the fly wliile the insect is feeding on the mucous membranes of the horse. Van Saceghem (1917, 1918) placed flies bred from larvae fed on infected manure, on skin lesions of a horse and produced infections of EQUINE GRANULAR DERMATITIS, caused by the presence of Habronema larvje in the skin. Hahronema microstoma (Schneider) Ransom and H. megastoma (Rudolphi) Seurat have also been shown to pass their developmental stages in Musca domestica. (See Chapter V.) NemathelmintJiLes : Nematoda: Ascaridae Ascaris lumhricoides Linnaeus, the cause of HUMAN ASCARIASIS, does not require an intermediate host. Stiles in 1889 fed Musca domestica larva? on female Ascaris and later found the eggs in diff'erent stages of development in both larvae and adult flies (Graham-Smith, 1913). Shir- core (1916) in British East Africa found the eggs in the intestines of Musca domestica in nature. Nicholls (1912) in St. Lucia found the eggs in the abdomens of flies, Borborus punctipennis Macquart {Limo- sina), taken at fecal matter. (See Chapter V.) Nemathelmvnthes: Nematoda: Oxyuridae Oxyuris Curvula Rudolphi, the EQUINE PINWORM, is recorded by Patton and Cragg (1913), as probably the species of Oxyuris, which in Madras is often found in the embryo stage heavily infesting the larvae of Musca nebulo. Oxyuris vermicularis Linnaeus, the HUMAN PINWORM, can be ingested in the egg stage by flies, according to Grassi (1883). 122 SANITARY ENTOMOLOGY Nemathelminthes : Nematoda: Ancylostomidae Ancylostoma duodenale Dubini, cause of HOOK WORM disease of man, has been found in the egg stage in house flies, Musca domestica, by Shireore (1916) in British East Africa, and it is therefore possible that the eggs may be placed on food, in which the hook worm larva could hatch and be directly conveyed into the body with the food. No develop- ment takes place in the flies. Necator americanu^ Stiles, the American HOOK WORM, was collected in the egg stage in the intestines of Limosina punctipennis in St. Lucia by Nicholls (1912). Galli-Valerio (1905) found that flies could carry on the surface of their bodies not only the eggs but also the larvae of this worm. Nemathelminthes: Nematoda: Trichosomidae Trichiuris trichiura (Linnaeus), the WHIP WORM of man, was col- lected in the egg stage by Shireore (1916) in British East Africa in the abdomen of Musca domestica and by Nicholls (1912) in St. Lucia in the abdomen of Borhorus punctipennis {Limosina) , and the latter succeeded in feeding Musca domestica on the eggs. It probably does not require the flies as immediate hosts, but is undoubtedly distributed in this manner. Thus to the already long list of serious diseases in whose spread the non-blood-sucking flies may play some part we may now add hog cholera, poliomyelitis, amoebic dysentery, Lamblian dysentery, Oriental sore, surra, murrina, yaws, purulent ophthalmia, trachoma, the fat-tapeworm of cattle, the fowl tapeworm, bilharziosis of man, the stomach worm of horses, equine granular dermatitis, human ascariasis (not normal method), equine pinworm, pin itch, two hook worms, and the whip worm, and possibly also smallpox, measles and scarlet fever. We found that the bacteria were only mechanically carried by the flies, except in the case of Bacillus anthracis. Among the protozoa also those organisms parasitic in vertebrates all seem to be mechanically transmitted. The various parasites mentioned, however, pass complete life cycles in the body of the fly. Among the worms, however, there are cases of external mechanical carriage, transmission of eggs through the intestinal canal, retention of the egg from larva to adult fly {Ascaris lumbricoides), and also cases of the fly serving as an intermediate host {Choanotaenia infundihulum, and Hahronema spp.). The last named worms are the only organisms known to be transmitted by the fly which work forward into the proboscis for transmission at time of feeding. , A bibliography of the works cited in the lecture follows : DISEASES BORNE BY NON-BITING FLIES 123 IMPORTANT GENERAL TEXTBOOKS Fantham, H. B., Stephens, J. W. W., and Theobald, F. V., 1916.— The Animal Parasites of Man. Wm. Wood & Co., New York, 900 pp. Graham-Smith, G. S., 1913. — Flies in Relation to Disease. Non-Blood- Sucking Flies. Cambridge Univ. Press, 292 pp. Herms, Wm. B., 1915. — Medical and Veterinary Entomology. The Mac- millan Company, New York. Hewitt, C. Gordon, 1914. — The House Fly, Musca domestica Linn. Its Structure, Habits, Development, Relation to Disease and Control. Cambridge Univ. Press, 382 pp. Hindle, Edward, 1911*. — Flies in Relation to Disease. Blood-Sucking Flies. Cambridge Univ. Press, 398 pp. Patton, Walter Scott, and Cragg, Francis William, 1913. — A Textbook of Medical Entomolog3^ Christian Literature Society for India, Lon- don, Madras and Calcutta, 764 pp. Riley, W. A., and Johannsen, O. A., 1915. — Handbook of Medical Entomology. Comstock Publishing Company, Ithaca, N. Y. SPECIAL REFERENCES Cao, G., 1898.— L'Ufficiale San. Riv. D'Igiene di Med. Patr., vol. 11, pp. 337-348, 385-397. Cao, G., 1906A.— Annali D'Igiene Sper., vol. 16, n. s., pp. 339-368. Cao, G., 1906B. — Annali D'Igiene Sper., vol. 16, n. s., pp. 645-664. Carter, R. M., 1909.— Brit. Med. Journ., vol. 2, pp. 647-650. Castellani, A., 1907. — Journ. Hygiene, vol. 7, p. 567. Castellani, A., and Chalmers, A. J., 1913. — Manual of Tropical Medi- cine, 2nd edit., p. 700. Celli, A., 1888. — Bullet, d. Soc. Lancisiana d. Ospedali di Roma, fasc. 1, p. 1. Cox, G. L., Lewis, F. C, and Glynn, E. E., 1912. — Journ. Hygiene, vol. 12, No. 3, pp. 306-309. Darling, S. T., 1911. — Journ. Infect. Diseases, vol. 8, No. 4, pp. 467- 485. Darling, S. T., 1911.— Parasitology, vol. 4, No. 2, pp. 83-86. Darling, S. T., 1912.— Journ. Exper. Med., vol. 15, No. 4, pp. 365- 366. Darling, S. T., 1912. — Trans. 15th Internat, Congress H3'g. and Demog., Washington. Davaine, C, 1870.— Bullet, de I'Acad. de Med., Paris, vol. 35, pp. 471- 498. 124 SANITARY ENTOMOLOGY Dorset, M., McBryde, C. N., Nile, W. B., and Rietz, I. H., 1919.— Amer. Journ. Vet. Med., vol. 14, No. 2, pp. 55-60. Dudgeon, L. S., 1919.— Brit. Med. Journ., No. 3041, April 12, pp. 448- 451. Dunkerly, J. S., 1912.— Central, f. Bakt., Paras, und Infekt., vol. 62, p. 138. Faichnie, N., 1909. — Journ, Royal Army Med. Corps, vol. 13, pp. 580- 584, 672-675. Fantham, H. B., and Porter, A., 1916. — Journ. Parasit., vol. 2, No. 4, pp. 149-166. Flu, P. C, 1916.— Geneesk. Tijdsclir. v, Nederl.-Indie, vol. 56, No. 6, pp. 928-939. Galli-Valerio, B., 1905.— Centralbl. f. Bakt. Orig., vol. 39, p. 242. Graham-Smith, G. S., 1910.— Repts. Local Govt. Bd., on Public Health and Medical Subjects, n. s.. No. 40, pp. 1-40. Graham-Smith, G. S., 1912.— Forty-first Ann. Rept. Local Govt. Bd. 1911-12, Suppl. Rept. Medic. OfF., pp. 304-329, 330-335. Grassi, B., 1883.— Arch. Ital. de Biol., vol. 4, pp. 205-208. Guberlet, J. E., 1916.— Journ. Am. Vet. Med. Assn., vol. 49, pp. 218- 237. Hofmann, E., 1888. — Correspondenzbl. d. arztl. Kreis- und Bezirks- vereine im Konigr. Sachsen, vol. 44, No. 12, pp. 130-133. Howard, C. W., and Clark, P. F., 1912.— Journ. Exper. Med., vol. 16, No. 6, pp. 850-859. Leboeuf, A., 1913.— Bull. Soc. Path. Exot., vol. 6, No. 8, pp. 551-556. Ledingham, J. C. G., 1911. — Journ. Hygiene, vol. 11, No. 3, pp. 333- 340. MacGregor, M. E., 1917. — Journ. Trop. Med. and Hygiene, vol. 20. No. 18, p. 207. Macrae, R., 1894.— Indian Med. Gazette, pp. 407-412. Maddox, R. L., 1885. — Journ. Roy. Microsc. Soc, Ser. 2, vol. 5, pp. 602- 607, 941-952. Marpmann, G., 1897.— Centralbl. f. Bakteriol., 1 Abt., vol. 22, pp. 127- 132. Morgan, H. deR., and Ledingham, J. C. G., 1909. — Proc. Roy. Soc. Med., vol. 2, pt. 2, pp. 133-149. Nicholas, G. E., 1873.— Lancet, vol. 2, p. 724. Nicoll, W., 1911.— Journ. Hygiene, vol. 11, No. 3, pp. 381-389. Nicholls, L., 1912.— Bull. Ent. Research, vol. 3, No. 1, p. 85. Nuttall, G. H. F., 1897.— Centralbl. f. Bakteriol., vol. 22, pp. 87-97. Nuttall, G. H. F., 1899. — Johns Hopkins Hospital Reports, vol. 8, Nos. 1-2, pp. 1-154. Patton, W. S., 1910.— Bull. Soc. Path. Exot., vol. 3, pp. 264-274. DISEASES BORNE BY NON-BITIXG FLIES 125 Patton, W. S., 1912.— Sci. Mem. Officers Med. & Sanit. Dept., Govt. India, No. 50, 21 pp. Ransom, B. H., 1913.— U. S. Dept. Agr., Bur. Anim. Ind., bull. 163, pp. 1-36. Robertson, A., 1908. — Journ. Trop. Med. and Hygiene, vol. 11, p. 213. Roscnau, M. J., 1916. — Preventive Medicine and Hygiene, pp. 206-252. Roubaud, E., 1918.— Bull. Soc. Path. Exot., vol. 11, No. 3, jjp. 166- 171. Sawtchenko, J. G., 1892. — Review in Ann. Inst. Pasteur, vol. 7. Scott, J. R., 1917. — Journ. Med. Research, vol. 37, No. 164, pp. 115, 121-121-. Shircore, J. O., 1916.— Parasitology, vol. 8, No. 3, pp. 239-243 Simmonds, M., 1892. — Deutsch. med. Wochenschr., No. 41, p. 931. Spillman and Haushalter, 1887. — Compt. Rend. Acad. Sci., vol. 105, pp. 352-353. Tebbutt, H., 1913.— Journ. Hygiene, vol. 12, pp. 516-526. Tizzoni, G., and Cattani, J., 1886. — Centralbl. f. d. med. Wissensch., Berlin, pp. 769-771. Torrey, J. C, 1912.— Journ. Infect. Diseases, vol. 10, No. 2, pp. 169- 176. UfFelmann, J., 1892.— Berliner klin. Wochenschr., pp. 1213-1214. Van Saceghem, R., 1917.— Bull. Soc. Path. Exot., vol. 10, p. 726; 1918, vol. 11, p. 575. Wayson, N. E., 1915.— U. S. Public Healtli Service, Pub. Health Repts., vol. 29, No. 51, pp. 3390-3393. Welander, 1896.— Wien. klin. AVochenschr., No. 52. Wenyon, C. M., 1911.— Kala Azar Bull., vol. 1, No. 1, pp. 36-58. Yersin, A., 1894.— Ann. Inst. Pasteur, vol. 8, pp. 662-667. CHAPTER VIII Important Phases in the Life History of the Non-Biting Flies ^ W. Dwight Pierce In the preceding lecture there was brought together an accumulation of evidence against the common flies that frequent our houses which should convince any one of the absolute necessity of keeping flies from our food, our houses and our bodies. We can only hope to accomplish this object by becoming familiar at least with the more important features in the life history of the flies. From the study of the transmission of diseases we may pick out for example a few points in the biology which need to be stressed, such as feeding habits, regurgitation of food, excreta, breeding places, oviposition, flight, attraction to odor. We are dealing in this lecture not only with the common house fly but also with most of the common flies which frequent our houses and are known as domestic flies. Of the common household flies, only one, the bit- ing stable fly, Stomoxys calcitrans, is omitted for future discussion. Students would do well to examine some book in which the diff*erent species are illustrated, so as to become familiar with the characteristic markings. It will then be a good plan to collect the various flies around the house and determine their species. Fairly good illustrations of common household flies are given by Howard and Hutchinson (1915), and Richardson (1917). The best illustrations of the flies are contained in Patton and Cragg's textbook (1913). Tables to species of common flies and also illustrations are presented by Riley and Johannsen (1915). It is also desirable to know how to identify the fly larvse when found. The best American work on this subject is by Banks (1912). See also Riley and Johannsen, p. 315. For general information on the life history, morphology, and anatomy of the house fly refer to Hewitt (1917). The flies are classified largely on the characters of the proboscis, antennae, wing veins, eyes and the arrangement of hairs. The larva? are classified on the characters of the spiracles, the cephalo-pharyngeal skeleton, tubercles, hairs and processes, ^This lecture was read July 23 and distributed Julj' 29, 1918. 126 PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 127 HOUSE FLY, MUSCA DOMESTICA LINNAEUS " (See Frontispiece) The common house fly, Musca domestica, is that insect charged with the carriage of the greatest number of diseases, and probably justly, be- cause of its frequentation of all types of excreta, garbage and waste, its common visitations to places where foods are handled, and also its visits to the human body. We have shown in the preceding lecture how it and its allies can carr}' disease and what diseases are charged against each. Now we will take a brief review of its life history in order to arrive at important data for handling its control. The house fly adult is jellowish to dark gray in color, with four equally broad longitudinal stripes on the thorax ; first three abdominal segments yellowish with a central black stripe and with two less distinct discal stripes. The males measure 5.8 to 6.5 mm. in length, and the females 6.5 to 7.5 mm. The eyes in the male are nearly contiguous and in the female are widely separated. This fly has been distributed by commerce to almost all parts of the civilized world. Certain features of its anatomy are of interest in the present study. The head is prolonged to form a proboscis which is enlarged at tip into the haustellum bearing apically the oral lobes or labella. These lobes bear a large number of channels kept open by incomplete chitinous rings called pseudotracheae, which are fully described by Graham-Smith (1913). The proboscis of the house fly is adapted to sucking and the absorption of liquid or liquefied food. It cannot take up very large particles of solid food. Nicoll (1911) found that the flies could not ingest particles larger than .045 mm. This therefore determines the size of worm eggs which can be ingested by the adult. We must assume therefore that when flies contain larger eggs, these were taken in by the larva. Normally, however, the food must pass between the bifid extremities of the chitinous rings of the pseudotracheal channels and pass along these to the mouth. These openings measure from .003 to .004 mm. in diameter. Solid par- ticles, however, are heaped up in a slight ridge in the channel between the oral lobes and are probably sucked into ' the oral pit and into the mouth. When the fly feeds on dry substances such as sugar, dried specks of milk, or sputum, etc., it first liquefies the substance b^^ a salivary secre- tion M^hich flows into the oral pit and onto the substance, being dis- tributed by the pseudotracheal channels. The moistening is also aided ° An appeal has been made to the International Commission for Zoological Nomen- clature for the retention of Musca in this sense with domestica as type. 128 SANITARY ENTOMOLOGY by the regurgitation of food from the crop, as proven by Graham-Smith, who fed flics upon carmine colored food, and found carmine stains on semi-fluid material upon which these flies later fed, for 22 hours. The intestinal canal is composed of pharynx, esophagus, crop, pro- ventriculus, ventriculus or chyle stomach, proximal and distal intestine and rectum. The esophagus passes from the pharynx through the cer- vical region into the thorax, in the anterior part of which it opens into the proventriculus, and from this same point a duct which is continuous with the esophagus passes back into the abdomen to the crop which is a bilobed sac, capable of considerable distention. This crop serves as a food reservoir. The fly feeds until it has engorged the crop, and often will continue feeding, the food then passing directly into the proventri- culus. The opening of the proventriculus into the esophagus is ventral. This organ is circular, flattened dorsoventrally. The ventriculus is tubular, narrowest in front and narrowing again in passing through the thoraco-abdominal foramen. The proximal intestine is the longest region of the gut, being considerably coiled. The distal intestine begins at the entrance of the Malpighian tubules, and is only curved once. It is sep- arated from the rectum by a valve. The rectum is composed of three parts, the intermediate of which is swollen to form the rectal cavity into which the four rectal glands empty. Food may remain in the crop for several days, and even when no further food is given, it requires many hours to empty the crop com- pletely. After feeding the fly usually retires to a quiet spot and cleans its head and proboscis. It frequently regurgitates its food from the crop in the form of large drops of liquid Avhich are subsequently slowly drawn up again and probably pass into the proventriculus. These drops of regurgitated food frequently are deposited, often for the purpose of moistening sugar and similar dr}^ foods. We may now see how easy it is for a fly which has fed on infected substances to contaminate other substances for days by regurgitation from the crop, as well as through fecal deposits. Experimental evidence has proven contamination by both the feces and the vomit. The fly's body is externally constructed so as to further aid in disease carriage. There are numerous hairs or seta? on the body, espe- cially on the legs. The last joint of the tarsus of each leg bears two claws and a pair of membranous pyriform pads or pulvilli. These pulvilli are covered beneath with innumerable, closely set, secreting hairs by means of which the fly is able to walk in any position on highly polished sur- faces. These sucker-like pads or pulvilli and the seta? of the legs are excellent bacteria carriers, and not infrequently larger organisms as mites, worm eggs, etc., are thus carried. The sexes of the house fly are about equal in number. Copulation PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 129 ma\^ take place, according to Hutchison (1916), as early as the day following emergence. Oviposition may begin on the third da3\ He cites a large series of observations on the prcoviposition period showing that eggs may be laid from ^\(, to 23 days after emergence, and that the period corresponds to temperature and humidity changes. At Washington the shortest period was obtained at 82° to 8-i° F., and in general the length of period increased with the decrease of temperature. Increase in humidity seems to hasten egg laying. The eggs are white, cylindrically oval, slightly broader at the pos- terior end with two distinct curved rib-like thickenings on the dorsal surface, along one of which the egg splits on hatching. These eggs are laid in masses averaging about 120, and a female may lay as many as four such batches, and probably under favorable conditions more. The eggs usually hatch in less than 24 hours, the time of course depending upon the climatic conditions. At 10° C. (40° F.) the egg period is two or three days; at 15 to 20° C. (59-68° F.) it is 24 hours; at 25-35° C. (77-95° F.) only 8 to 12 hours, according to Hewitt (1917). The larvae are white, smooth, cylindrical maggots, tapering at the head end and considerably enlarged at the tail end. When viewed by trans- mitted light a dark chitinous structure can be seen in the anterior regions. This is called the cephalopharyngeal skeleton and is partially extrusible. Each species of fly larva is distinguished by the form of this skeleton and hence if a slide mount is made of a skin boiled in potash, the species can be identified by this and one or more other characters. The three larval stages differ somewhat in the form of this skeleton so that it becomes possible to determine exactly the stage of development. The body is composed of fourteen segments of which the second is the pro- thorax. This segment at its posterior margin bears the anterior spiracles which are fan-shaped and have six or seven lobes. This segment is fol- lowed by the mesothorax, metathorax, and eight abdominal segments. The ninth and tenth (anal) segments are small and ventral. The anterior portion of the venter of each of the first eight abdominal segments bears spiniferous pads which assist in locomotion. The eighth or last apparent segment bears the spiracular plates. These spiracular plates afford the best means of identification of fly larvae. In the first two stages each plate consists merely of two oblique slits on a slight prominence. In the third stage they are well defined plates, D-shaped, closer together than their width, with flat faces opposed, each with three sinuous slits. In connection with this larval description, we may call attention to errors existing in many larval descriptions. The thoracic spiracles belong to mesothorax but often appear to have migrated to the prothorax. The large terminal spiracles of Dipterous larvae are always on the eighth 130 SANITARY ENTOMOLOGY segment, as in almost all orders of insects. Tlie ninth and tenth seg- ments are apt to be small and obscure and center around the anus, which belongs to the tenth. The larval period varies in response to climatic stimuli, but under favorable conditions is about four days in length. When full grown the larva varies from 10 to 12 mm. in length. Pupation takes place within the last larval skin which shrinks and hardens to form a reddish case or puparium. This period lasts from 3 to 10 days. When the fly is ready to emerge it pushes off the cap or head end. The entire developmental period may require from eight to eighteen or more days. Kisliuk has found pupae of the fly in manure piles at various times during the win- ter, which of course indicates that the developmental period may occupy an entire winter if the pupa is caught by cold weather. Bishopp, Dove and Parman found that adults emerged from immature stages which had been in manure for six months. Hutchison's observations at Washing-ton, D. C, confirm these findings. The adult flies are capable of considerable flight. Parker demon- strated a migration of two miles in his Montana studies. Bishopp and Laake (1919) record the flight of marked house flies of thirteen miles. In this connection the most interesting contribution is that of Ball (1918) in which he shows that house flies apparently migrated with the wind from 46 to 95 miles from mainland to a tin}^ island. The house fly has been found breeding in horse manure, human excre- ment, and hog manure very freely and to some extent in cow and chicken manure. It lays its eggs in a great variety of decaying animal and vegetable materials, such as slops, spent hops, moist bran, ensilage, rotting potatoes, dead animals, excreta-soiled straw, paunch contents of slaughtered animals, soiled paper and rags, etc. THE BLUE BOTTLE FLIES OF THE GENUS CALLIPHORA ^ The large blue bottle fly, Calliphora vomit oria Linnaeus (plate I, fig. 1) and its near relative C erythrocephala Meigen are often found in houses. These flies have also been shown to be dangerous insects because of their ability to transmit disease. In fact they are much more likely to directly transmit disease organisms than the house fly because of their habits of breeding in flesh which gives them also the name blow flies. The adults are grayish on the thorax and dark metallic blue with sug- gestions of silver on the abdomen. In vomitoria the genae are black and beset with golden red hairs, while in erythrocephala the genae are fulvous to golden yellow and beset with black hairs. ' An appeal has been made to the International Commission for Zoological Nomen- clature for the retention of Calliphora in this sense with vomitoria as type. PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 131 These flies are necrophagous and deposit their eggs upon any fresh, decaying or cooked meat, and upon dead insects ; they breed occasionally in human excrement and sometimes will deposit their eggs in open flesh wounds. On the battle fronts of Europe and Asia where the wounded lay for long periods and where many dead bodies remained uncared for, these flies multiplied to tremendous numbers and were largely responsible for the carrying of infections to wounds. When a fly lays its eggs in living flesh and the larva? develop therein, the infection is called myiasis. This subject is of such importance that two entire lectures is devoted to it (Chapters XII and XIII). Important as they are, the blow flies are usually subordinated to the house fly in the discussion of "dangerous flies, but thorough investi- gations of these species are more than likely to greatly increase their standing as disease carriers. The eggs are deposited in masses of as many as 300 and a single fly may possibly deposit three batches. They hatch in from 10 to 24< hours after deposition. The larvae of C. erytlirocephala may be distinguished from the house fly larvjE by having usualh' nine but sometimes up to twelve lobes in the anterior (thoracic) spiracles; an anterior scabrous swollen ring on each of the first eight segments of the abdomen, and a ventral groove on each segment beneath; the stigmal field concave, surrounded by three pair of tubercles above, and two large and one small pair below; the stigmal plates about once and a fourth their diameter apart, each with three straight slits, directed principally toward the opposite jolate; and also, by having an anal pair of tubercles. The larval characters are illustrated by Hewitt and also by Banks. The larval period requires seven and a half to eight days at 23° C. (73.5° F.) and the pupal period fourteen days, according to Hewitt. Bishopp and Laake found the larvae to attain full growth in three to four days and the time from deposition of eggs to emergence of adults was 15 to 20 days. THE SHEEP MAGGOTS OU GREEN BOTTLE FLIES The European sheep maggot fly, Lucilia sericata Meigen, is primarily an outdoor fly but occasionally is found indoors, especially in farm and country houses. It is more brilliant than the Calliphoras, being of a burnished gold with a shining, bluish-green color. The flies are strongly attracted to meat and carcasses in w^hich they lay their eggs. They also occur on human and animal excrement. The larvae breed readily in all these substances. In Europe the flies very commonly lay their eggs in matted wool and on the flesh on the backs of sheep, and the larvae 132 SANITARY ENTOMOLOGY breed in the flesh causing external myiasis. This species attacks ulcers and sores of men and animals. Its most common attack on sheep and calves is made on the soiled rumps of animals suffering from diarrhea. No doubt the flies also serve as distributors of the diarrhea. The larva has eight-lobed anterior spiracles. The same number of tubercles margin the stigmal plate behind as in Calliphora, but they are smaller and sharper. The stigmal plates are about one-half their diameter apart, each with three straight slits, directed somewhat toward each other, but also downward. Undoubtedly under battle front conditions this ^y can be expected to visit human wounds and breed in them even more readily than Cal- liphora. It has been shown by Cao to transmit anthrax with equal ease. Several other species of Lucilia have like habits, and the larvae of two of these, L. caesar Linnaeus (not sericata Meigen), and L. sylvarum Meigen have been described and illustrated by Banks. The larvae of L. caesar measure 10 to 11 mm. in length and have not adequately been separated from Calliphora crytlirocephala. The larval period averages about fourteen da3^s and the pupal stage about the same. Bishopp and Laake state that in Texas, during warm weather, the larval period ranges from three to twelve days, the pupal stage five to sixteen days and the total developmental period eleven to twenty-four days. This fly is illustrated in plate I, Fig. 2. OTHER SCREW WORMS AND BLOW FLIES The question of myiasis, which covers screw worms and blow flies, is to be considered in separate lectures (Chapters XII and XIII), but mention must be made of tliem at present because undoubtedly many infectious diseases are carried by these insects which attack alike live flesh through wounds, and dead animals. I would hardly hesitate to claim that probably all such flies may carry anthrax at least, and probably do carry other diseases. Bishopp, Mitchell, and Parman (1917) describe quite fully the habits- of the common American screw worm, Chrysomya macellaria Linnaeus '^ (plate I, fig. 3, plate II) which breeds in both carcasses and flesh wounds (plate IV). They also treat the black blow fly Phormia regina INIeigen (plate I, fig. 4), and other species. The large hairy blow fly, Cynomyia cadaverina, Robineau-Desvoidy, and the gray flesh flies Sarcophaga texana Aldrich, S. tubcrosa var. sarracenioides Aldrich, S. sarraceniae *An appeal has been made to the International Commission on Zoological Nomen- clature to retain Chrysomya in the sense with macellaria as type. PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 133 Pl.vte I. — Screw worms and blow flies. Fig. 1 (iipf^er left). — The blue bottle fly, Cal' liphora vomitoria. Fig. 2 (upper right). — The green bottle fly, Lucilia caesar. Fig. 3 (lower left). — The American screw worm, Chrysomi/a macellario. Fig. 4 (lower right).— The black blow fly, Phormia regina. (Howard and Pierce, photos by Dovener.) 134 SANITARY ENTOMOLOGY Plate II. — J^ggs ot the American screw worm, Uhrt/domja mactUaria, on meat. (Bishopp.) PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 135 Riley (plate III, fig. 1) and S. robust a Aldrich are also among the most common flesh flies. Froggatt (1915) has given a very fine treatment of the most impor- tant sheep maggot flies and has presented colored illustrations of some of them. All of these flies are likely to be found in houses and markets and when given the opportunity will lay eggs on meat off'ered for sale or exposed in kitchens or mess halls. If this meat is already cooked there is a good chance of the eggs being ingested and giving rise to gastrointestinal myiasis. But the danger from flesh flies is greater than the mere causation of external or internal myiasis. The flies which lay the eggs may have bred in diseased carcasses, and if so, probably will deposit with the eggs a glutinous film containing bacteria from these carcasses, for it will be remembered that the fly larva takes up these bacteria and they may remain in its body until it as a mature fly lays its eggs, and even longer. It must be borae in mind that because conditions in the imme- diate vicinity are sanitary, does not mean that the flies which come are sanitary, because Bishopp and Laake (1919) record the flight of marked Clirysomya macellaria flies for 15 miles, and of Phormia regina for 11 miles. OTHER EXCREMENT BREEDERS Others of our house flies, as the non-biting stable fly, Muscina stabulans Macquart (plate III, fig. 2), the lesser house fly Fannia cani- cuJaris Linnaeus (plate III, fig. 3), and the latrine fly F. scalarts Fabricius breed in decaying vegetables and animal matter. Muscina stabulans looks ver}^ much like the house fly, but it is a little more robust. It is gray and the thorax is marked with four longitudinal black lines. Parts of the legs and scutellum are reddish. The principal diff'erential character is in the wing venation. The larva, however, is easily distinguished from Musca domestica, by the six-lobed anterior spiracles and the anal stigmal plates scarcely elevated, less than their diameter apart, each with three very short slits pointing towards those of the opposite plate. It breeds in decaying and live vege- table matter, human and animal excreta, and has even been reared from insect puparia. It breeds likewise in raw and cooked meats and on car- casses. It is therefore a very potential disease carrier, possessing all the opportunities of the house fly, with which it may already be mixed in medical literature. Fannia canicularis and F. scalaris are two flies commonly found in houses, which greatly resemble the house fly, but the former may be dis- tinguished by the presence of only three dai'k stripes on the thorax instead of the four found in the house fly. The larvae of these flies are very 136 SANITARY ENTOMOLOGY Plate III. — Flies with dangerous habits. Fig. 1 (upper left). — A flesh fly, Sarcophaga snrraceniae. Fig. 2 (upjier right). — The non-biting stable fly, Miixcina sfnhiilam. Fig. 3 (lower left). — The lesser house fly, Fannia canicularis. Fig. 4 (lower right). — The brilliant greea fly, Pseudopyrellia cortiicina. (Howard and Pierce, photos by Dovener.) i PHASES IN THE LIFE HISTORY OF NON-BITING FLIES 137 readily separated by the large number of processes on all the seg- ments. The posterior spiracles are located on raised processes and are not plates as in the species mentioned above. In F. canicidaris there are four lobes to the posterior spiracles and six finger-like lobes to the anterior spiracles (see Hewitt, 1917) (see figs. 14 to 19). These flies breed in excrement, and in all kinds of decaying vegetable matter and are often found in cases of intestinal myiasis. REFERENCES Ball, S. C, 1918. — Migration of Insects to Rebecca Shoals Light Station and the Tortugas Islands, with Special Reference to Mosquitoes and Flies. Carnegie Inst., Washington, Publ. 252. Banks, Nathan, 1912. — The Structure of Certain Dipterous Larvae with Particular Reference to Those in Human Foods. Bishopp, F. C, 1915.- — Flies Which Cause Myiasis in Man and Animals. Some Aspects of the Problem. Journ. Econ. Ent., vol. 8, pp. 317- 329. Bishopp, F. C, and Laake, E. W., 1919.— The Dispersion of Flies by Flight. (Abstract) Journ. Econ. Ent., vol. 12, pp. 210-211. Bishopp, F. C, Mitchell, J. D., and Parman, D. C, 1917.— U. S. Dept. Agr., Farmers' Bull. 857. Froggatt, W. W., 1915.— Sheep Maggot Flies. Dept. Agr., New South Wales, Farmers' Bull. 95. Graham-Smith, G. S., 1913. — Flies in Relation to Disease. Non-blood- sucking Flies. Cambridge Univ. Press. Hewitt, C. G., 1917. — The House Fly. Cambridge Univ. Press. Howard, L. O., and Hutchison, R. H., 1915.— House Flies, U. S. Dept. Agr., Farmers' Bull. 679. Hutchison, R. H., 1916.— U. S. Dept. Agr. Bull. 345. Nicoll, W., 1911.— Journ. Hygiene^ vol. 11, No. 3, pp. 381-389. Parker, R. R,, 1916. — Dispersion of Musca domestica under City Condi- tions in Montana. Journ. Econ. Ent., vol. 9, pp. 325-354. Patton, W. S., and Cragg, F. W., 1913.— A Textbook of Me*dical En- tomology. Richardson, C. H., 1917. — The Domestic Flies of New Jersey. New Jer- sey Agric. Exp. Sta., Bull. 307. Riley, W. A., and Johannsen, O. A., 1915. — Handbook of Medical Entomology. CHAPTER IX Common Flies and How to Tell Them Apart ^ C. T. Greene Only a few of the very common flies have been included in this chap- ter; the flies that are likely to appear near any house or in any camp. All of them may be attracted by the odors of fresh and cooking foods. In the following pages are presented two tables, one to separate the dif- ferent species of the adult flies, and the other to separate the diff^erent larvae or maggots of the flies. All the terms for the different parts of the flies and maggots have been made as plain as possible so that the Mouth F/!RT^. Fig. 10.— Mouth parts of flies: a, Suctorial type; h, biting type. (Greene.) tables can be used by a non-entomologist. In the first table for the adult flies is given the style of the mouth-parts (see fig. 10), that is, whether they are adapted for biting or are simply suctorial, then the common name is given, and then the scientific name. In the second table the larvae or maggots can be separated into diff'erent species. Under the name of each species, the larva or maggot is described in further detail and here mention is made as to where the species will breed. *This lecture was presented September 9, and issued September 11, 1918. It has been somewhat modified. 138 COMMON FLIES AND HOW TO TELL THEM APART 139 All the Sarcophagid or "flesh flies" can be readily separated from all the other flies in the following table because their bodies are entirely gray. The head is rather a bright red, the top of the back has three parallel dark stripes and the top of the abdomen has lighter reflecting areas, giving it somewhat of a checkered appearance. TABLE TO SEPARATE THE ADULT FLIES I. Grayish flies with from two to four longitudinal stripes more or less indicated on the thorax. 1. Dark gray, medium sized fly; top of thorax with four parallel, black stripes; sides of abdomen with a large yellow area (variable in size and never definitely outlined) ; moutli-parts of the suc- torial type (see fig. 10a), never for biting; variable in size but — ^Abdomen Fig. 11. — Diagrammatic sketch of the house fty, Musca domestica. (Greene.) average about one-quarter inch in length. The common house fly (Frontispiece, figs. 11, 12a) also called typhoid fly. Musca domestica Linnaeus. 2. Brownish-gray fly, slightl}^ larger and broader than the house fly. Top of thorax with two long, parallel, black stripes and on each side of these is a large black dot, below which is a black stripe about half as long as the two long stripes. Abdomen with two or three cone-shaped dark brown spots in the center and two or three round spots on each side (fig. 12c). Mouth-parts piercing or biting type (fig. 10b). Stable fly, also called biting house fly (fig. 46). Stomoxys calcitrans Linnaeus. 3. Very dark gray fly, smaller and more slender than the house fly. Abdomen pointed and more conical in shape. Yellow spots on the sides definitely outlined (fig. 12b). ]Mouth-parts are of the suc- torial type (fig. 10a). The small house fly (plate III, fig. 3). Fannia- canicnlaris Linnaeus. 4. Gray fly, a little larger tlian tlie house fly. (About the size of Stomoxys calcitrans.) Top of thorax has two short, black 140 SANITARY ENTOMOLOGY stripes. Joints of legs reddish at base. Abdomen is gray and in certain lights there are paler gray areas which look like spots but there are never any definitely outlined spots. Mouth- parts suctorial type (fig. 10a). Another stable fly (plate III, fig. 2). Muscina stabulans Linnaeus. II. Bluish, or greenish flies. 1. Large blue fly, with grayish thorax (average length three-eighths to seven-sixteenths of an inch). This fly is rather broad and robust and in certain lights the abdomen shows paler, reflecting areas but not definite spots. Mouth-parts suctorial type (fig. 10a). The common blow fly. Lower part of head (cheeks) red- dish and the beard black. Calliphora erythrocephnla ]Meigen. 2. A slightly larger fly than the preceding but more shiny and a deep greenish blue. Abdomen slightly more pointed and of an House Fly MuSC/l OOMESTte/lL Little Hous£ Fly St/ibL£ Tly f^NNI/l CANIZUL/IKIJ. L ^TOMOKYS CALCITR/tNS. Fig. 12. — Abdominal markings of three common house flies: a, the house fly, Musca domestica; b, little house fly, Fannia canicidaris; c, stable fly, Stomoxys calcitrant. (Greene.) In these diagrams the relative size of the abdomen is shown. The light areas in a and h represent yellow markings and are variable in size. In fig. c the markings of the last segment may be present or absent. 4. 5. even coloration (no reflecting spots). Mouth-parts suctorial type (fig. 10a). Lower part of head black and the beard red. An- other blow-fly (plate I, fig. 1). Calliphora vomit oria Linnaeus. Much smaller fly, shiny green with a decided whitish bloom on the thorax and abdomen. Mouth-parts suctorial (fig. 10a). A green bottle fly. Lucilia sericata Meigcn. A slightly smaller fly, shiny, metallic green with a decided bluish tinge and no white bloom. Mouth-parts suctorial (fig. 10a). Green bottle fly (plate I, fig. 2). Lucilia caesar Linnaeus. A dark green fly, little larger than the above species. It is shiny with bluish tinge. Top of thorax with three dark longitudinal stripes. Thorax often has a bronze tinge. (Average length five- sixteenths to three-eighths of an inch.) Mouth-parts of the suc- torial type (fig. 10a). The "screw-worm fly" (plate I, fig. 3). Chrysomya macellaria Fabricius. COMMON FLIES AND HOW TO TELL THEM APART 141 6. Deep, shiny blue fly often with a blackish tinge (about five-six- teenths of an inch in length). Mouth-pai'ts of the suctorial type (fig. 10a). The black blow fly (plate I, fig. 4). Phormia regina ISIeigen. III. Ashen gray to deep gray flies. Top of thorax with three blackish, longitudinal stripes. The abdomen has lighter gray reflecting spots (in certain lights). The diff'erent species vary in size from a small fly up to a half inch in length. Mouth-parts are of the suctorial type (fig. 10a). Flesh flies (plate III, fig. 1). Sarcophagidae. THE LARVAE OR MAGGOTS There is a considerable number of flies whose larva? or maggots either regularly or occasionally live in substances used by man as food. The great majority pass through the intestinal tract Avithout our knowledge, for most of them cause little or no trouble. Many dipterous larvcB occur in decaying fruits and vegetables and on fresh and cooljed meats. The blow fly, for example, will deposit on meats in a pantry; while other maggots occur in cheese, etc. Pies and puddings in restau- rants are often accessible and very suitable places for flies to deposit their eggs and no doubt a great many maggots are swallowed in this way. The occurrence of dipterous larvae in man is known as "myiasis." Various names or divisions are given, as "myiasis externa" or "myiasis dermatosa" for larvae in the skin or wounds ; "myiasis intestinalis" for those in the alimentary canal ; and "myiasis narium" for larva? in the nose. The presence of larva? in the nose is rather accidental in this country and usually due to the "screw-worm." In tropical countries this type of myiasis is quite common. The larvae of the ox-warble or bot-fly {Hypodenna lineata Villers) sometimes occur in man. There are various cases recorded, mostly of children, where, in the Avinter time, a larva is observed under the skin, usually in the neck or shoulders, and upon removal proves to be the larva of the heel fly in the second stage. Bot infestation is sometimes called "creeping worms," and many cases have been recorded by anny surgeons on the Mexican border. These cases are probably contracted by men sleeping in stable yards. Descriptions of larvae or maggots ^ All the larva; mentioned here are broadest near the tip or tail of the body, and taper forward to the head. * In the following discussion the visible body segments are numbered from head to anus irrespective of their scientific nomenclature. — W. D. Pierce. 142 SANITARY ENTOMOLOGY The larva is divided into fourteen parts, of which eleven are distinct, called segments, and the first segment is the head. The head appears to be bilobed, or divided into two parts when viewed from above, and each lobe bears a minute cylindrical tubercle or papilla (fig. 13). Below is the mouth opening; at one side and above it is tlie pair of mandibles or great hooks (fig. 13). The second segment or prothorax bears on each side, in the full grown larvae, a short fan-shaped process called the an- terior spiracle. The eleventh body segment which might be taken for the last is often a fusion of the seventh to tenth abdominal segments. The eighth abdominal segment can always be identified by the stigmal plates ^hgmaf fiyd (conf^ain/ng ^osfen'or sh'^maf pldes) \ /inal f-uUrcU. Vzn-fraf fusiform area. Lahra/ fusiform area |s An^z rior SPirac/e. .s Fig. ]3. — Characters of a muscid fly larva. (Greene.) Segment 1 is the head; 2-4 are thoracic segments; 5-11 are abdominal. Segment 11 really contains the seventh to tenth abdominal segments, the spiracles being on the eighth, the anus in the tenth. or lobes. The ninth and tenth are usually small and ventral and enclose the anus. For further details see fig. 13. Table to Separate the Larvae (Maggots) I. Spiny larvae. 1. A larva with the body flattened; down the middle of the back are two rows of spines or processes, there are also two rows along the under side and a single row of spines along each side. These spines or processes are pointed and covered with many bristles. There are also two stigmal plates on top of the last segment. (Figs. 11^-16.) Fannia canicularis. 9,. The larvae of Fannia scalaris are similar (figs. 17-19), but the processes have fewer side branches. II. Smooth larvae. A. With one great mouth-hook ; slits in stigmal plate winding. 1. Body broadly rounded at rear end, without spines. Stigmal plate with three winding slits (figs. 20 to 22). Musca doinestica. COMMON FLIES AND HOW TO TELL THEM APART 143 2. Body same as above species, stigmal plate with three S-shaped sHts (figs. 23, 24). Stomoxys calcitrans. B. Two great mouth-hooks ; slits in stigmal plate not winding. 1. Body slightly rounded at rear end, faintly spined and with three short, pointed slits in stigmal plate (figs. 25, 26). Muscina stahulans. Fig. 14. — Larva of the little house fly, Fannia canicularis. Greatly enlarged. (Howard and Pierce, drawing by Bradford.) Fig. 15. — Dorsal view of eighth alvdominal segment of the larva of Faniiia canic- nlaris. Very highly magnified. (Draw- ing by Bradford.) Fig. 16. — ^'entral view of terminal seg- ments of Fannia canicularis; the nintli and tenth segments are comprised in the small zone around the anus. Very highly magnified. (Drawing by Brad- ford.) 3. 4. Stigmal plates wide apart, each with three straight slits nearly transverse to the body and a distinct button (figs. 27, 28). Calliphora erythrocephala. Calliphpra vomitoria. Stigmal plates about half their diameter apart, each with three straight slits directed somewhat downward (fig. 31). Lucilia sericata. Stigmal plates less than their own diameter apart, each with three straight slits pointed downward; no button (figs. 29, 30). Chrysomya macellaria. 144 SANITARY ENTOMOLOGY 5. Stigmal plates at bottom of a deep pit ; each plate has three slits pointing downward, plates less than their diameter apart ; no button. Sarcophagidae. Fannia canicidaris Linnaeus and F'Onnia scalaris Fabricius These larvje are brownish yellow in color. The body is quite flattened, narrow and pointed in front. The peculiar spines or projections on the body will separate them from the other species. The lana averages nearly three-eighths of an inch in length (figs. 14-19). (See Chapter vm.) Fig. 17. — Larva of Faiinla scalaris, the latrine fly, greatly magnified. Pierce, drawing by Bradford.) (Howard and Fig. 18. — Dorsal view of eighth abdominal segment of the Fannia scalaris. Very highly magnified. (Drawing by Brad- ford.') Fig. 19. — ^'entral view of terminal seg- ments of Fannia scalaris; the ninth and tenth segments are comprised in the small zone around the anus. Very highly magnified. (Drawing by Brad- ford.') Since the lar\'ae of this genus feed on fruit and vegetables that are just beginning to decay, one can readily see that they are often swallowed by people. There are many records of the passage of lars'se or maggots of this genus. At least some species of this genus breed in human feces, therefore they may be possible conveyers of disease. Musca domestica Linnaeus The larva of the house fly is slender and tapering in front and large and somewhat rounded behind. From above, the head is divided into two 1 COMMON FLIES AND HOW TO TELL THEM APART 145 parts with a tiny papilla on each side (fig. 20) and there is but one great hook. The anterior spiracles (fig. 21) show six or seven lobes; on the under side of the sixth and following segments there is a trans- verse, swollen area, wider in the middle and somewhat pointed toward each end. These areas are provided with minute teeth. The area is slightly prominent and shows two approximate processes. The stigmal field is barely if at all concave and not outlined by tubercles ; the posterior spiracles (fig. 22) are prominent, less than their own diameter apart and each with three winding slits and a button at the base. In some cases two of the winding slits are apparently connected. The second- stage larvjE has two straight slits in each stigmal plate, while in the first larval stage there are two smaller slits on a tubercle each side of the Fig. 20 (left). — Larva of Mhisca dam^stica; dorsal view of head and porthorax. (Greene.) Fig. 21 (center). — Larva of Mnsca domestica; lateral view of terminal segments. (Greene.) The spiracles are located on the eighth abdominal segment. The ninth and tenth segments are ventral and not very distinct, enclosing the anus. Fig. 23 (right). — Larva of Musca domestica; enlarged sketch of right stigmal plate. These plates are less than their breadth apart. (Greene.) middle and in this stage there are no anterior spiracles. (See Chapter vni.) The larva of the house fly is rarely swallowed, but there are records to that effect. It sometimes breeds in decaying fruits and vegetables. The principal breeding place is in horse manure. It also breeds in human excrement and because of this habit it is very dangerous to human beings. Stomoxys calcitrans Linnaeus The larva of this species is very similar to that of the house fly, with a single great hook; the anterior spiracles have five lobes (fig. 23) ; the sixth and following segments have each an area on the under side pro- vided with tubercles ; this area is wider in the middle ; anal area has two submedian tubercles and three each side of these; above them is a row 146 SANITARY ENTOMOLOGY of minute granules, ending each side in a larger granulate tubercle ; there are no tubercles outlining the stigmal field ; the stigmal plates are sub- triangular, about one and one-half times their diameter apart, black, and each with three pale areas containing an S-shaped slit (fig. 24). These slits are never near each other like in the house fly, and there is no apparent button. This larva commonly breeds in manure of various kinds, but also in Fig. 23. — Larva of Stomoxys calcitrans: enlarged sketch of thoracic spiracles. (Greene.) decaying matter, and is not often passed by people, but there is one record. Horse manure, cow manure, and warm, decaying vegetation, like old straw and grass heaps, are common breeding places. Fig. 24. — Larva of Stomoxys calcitrans: enlarged sketch of right stigmal plate. These plates are one and one-half times their breadth apart. (Greene.) Muscina stabulans Fallen Head of larva (fig. 25) divided into two parts from above, no dis- tinct papilla ; two great hooks close together ; anterior spiracles with about six lobes (fig. 25b). The surface of the segments is mostly smooth. Beginning with the fifth segment, on the under side, there is a basal, transverse, swollen area, furnished on the crest with rows of teeth ; each of tliese areas is divided on the median line. On the next to the last segment there is a similar area at the tip, but not divided. The seg- ments below also show a transverse line before the middle. The last segment has the anal basal area with spines, but not very prominent, and bears a median and three lateral tubercles with spines. The tubercles COMMON FLIES AND HOW TO TELL THEM APART 147 are nearly in a transverse row. The rounded tip of the body (fig. 25c) shows, across the middle, faint traces of four low cones. The stigmal plates (fig. 26) are scarcely elevated, black, less than their own diameter apart, and each with three very short slits pointing towards those of the opposite plate. This larva is common in decaying vegetable matter; and has been reared from rotten apples, pears, squash, mushrooms and dead insect o. Fig. 25. — Larva of Muscina stabulans: a, Side view of head and prothorax; b, an- terior or thoracic spiracles; c, side view of terminal segments of abdomen. (Greene.) larvje. In one case a considerable number were passed by a child suf- fering with summer complaint. Laboulbene records larvae of this species vomited by a person suffering from bronchitis. Fig. 26. — Larva of Muscina stabulans: enlarged sketch of right stigmal plate. These plates are less than their breadth apart. (Greene.) CallipJiora erythrocepTiala Meigen The head of this larva is distinctly divided into two parts from above (fig. 27, side view of head) ; each part or lobe has a tiny papilla. There are two well separated mouth hooks. The anterior spiracles have from nine to twelve lobes. Beginning with the third, each segment shows an apical swollen ring or girdle, whose surface is scabrous (roughened like a file) ; these rings are broader below than above, and are here notched on the posterior middle. Each ventral segment, beginning with the fifth, is divided by a transverse groove near the middle. The anal area shows a smooth median process, divided in the middle, and at each outer comer is a cone. The stigmal field is rather concave, the upper lip with three small tubercles on each side, the lower lip with two larger tubercles on each side, and a median pair smaller and lower down. The stigmal plates are about once and a fourth their diameter apart, each with three 148 SANITARY ENTOMOLOGY simple straight slits directed slightly downward but mostly toward those of the opposite plate; the button is distinct (fig. 28). The blow-fly deposits eggs on dead animals, and also on fresh and cooked meats. As such are often accessible to them in pantries, it is readily seen that many larvae are swallowed by people each year; there are, however, comparatively few records published, probably because the polluted food causes no trouble. CalUphora vomitoria Linnaeus This larva appears to be identical with that of CallipJiora erythroceph- ala. There seem to be no visible characters to separate it from this latter species (figs. 27 and 28). The habits are about the same. Fig. 27. — Larva of CalUphora erythrocephala: side view of head and protliorax. (Greene.) Lucilia sericata Meigen Body rather stout, not slender in front. The head is distinctly divided into two parts or lobes, with distinct papilla(figs. 31a, b). The Fig. 28. — Larva of CalUphora erf/thiorephala: enlarged sketch of left stigmal plate. These plates are one and one-quarter times their breadth apart. (Greene.) two great mouth hooks are well separated. The anterior spiracles are provided with about eight lobes. The surface of the body is mostly smooth; the sides of segments 3, -1 and 5 are bilobed; beginning with segment 6 there is a basal ring girdle, roughened. These girdles on seg- ments 6 to 9 are widened on the middle of the under side of the larva; the sides are also swollen, but not plainly bilobed, except those near the tip. The under sides of the segments are transversely divided by a line or furrow in the middle. The last segment is short, the stigmal field occupying most of the tip. The stigmal field has a slightly de- pressed, upper lip with three sharp tubercles on each side, the interme- diate one hardly smaller than the otliers ; and a lower lip with two large, 1 COMMON FLIES AND HOW TO TELL THEM APART 149 sharp tubercles on each side, and a median pair more remote from the margin (fig. 31c). The anal area is rather sunken with a small rounded tubercle at each outer corner. The stigmal plates are about one-half their diameter apart, each with three straight slits, directed somewhat towards each other, but also downward. a. Ir. c. Fig. 31. — Larva of Lucilia sericata: a, dorsal view of head and prothorax; b, lateral view of head and thorax; c, lateral view of last abdominal segments. (Greene.) This larva is mentioned on account of the adult which is very likely to be met with. This larva is mostly injurious to sheep. Meinert has reared another Lucilia (L. nobilis Meigen, of Europe) from larvas taken from the ears of a sailor. Fig. 29. — Larva of Chrysomya macellaria: enlarged sketch of side of head and pro- thorax. (Greene.) Chrysomya inacellaria Fabricius The head from above is distinctly bilobed (fig. 29). There are two distinct hooks. The anterior spiracles are very short, and contain only Fig. 30. — Larva of Chrysomya macellaria: enlarged SKetch of left stigmal plate. These plates are less than their breadth apart. (Greene.) 7 lobes (fig. 29). The posterior upper part of segment 1 is swollen and with many spines (fig. 29). Each of the following segments (except 2) has a basal, swollen ring, armed with teeth pointing backward, the teeth of the front rows are always larger. Beginning with segment 6 the under 150 SANITARY ENTOMOLOGY part of each ring is much broadened and divided transversely by a narrow smooth space. On segments 5 to 10 there is on each side behind a fusi- form swollen area pressing against the swollen ring of the next segment ; this area also has spines. The tip of the body shows on the dorsal part a great cavity, in the bottom of which are the stigmal plates, each with three straight slits, those of one sub-parallel to those of the other ; there is no button (fig. 30). Behind this cavity is a higli, transverse, spiny crest ; and the ventral part of the tip shows an area covered with spines bearing two rather widely separated, prominent, smooth tubercles. The upper edge of the tip shows four small conical tubercles. Plate IV. — Screw worm injury to a yearling calf. (Biahopp.) The larva of this insect is called the "screw-worm," and occurs in sores and wounds of domestic animals and also in man. There are various records of its presence in the ears and nose, or nasal cavities, of people ; in swellings near the nose ; in a boil under the arm ; under the skin of a child ; and in the navel of a child. It is hardly a possible factor in intestinal myiasis of man, and most of such recorded cases probably belonged to some species of Sarcophaga whose larvje are very similar in appearance to those of the screw-worm. Sarcophagidae The Sarcophagidae have two great hooks, and the posterior stigmal plates have three slits as in Calliphora erythrocephala and Lucilia seri- COMMON FLIES AND HOW TO TELL THEM APART 151 cata. However, these slits are not directed toward those of the opposite plate but are sub-parallel to them. The stigmal field is strongly depressed to form a deep pit, and the stigmal plates are at the bottom of this pit. The segments of the body bear complete rings of spinose areas, and often supplementary pads on the sides. Sarcophaga larvae prefer animal matter, breeding extensively in car- casses. They have been found in cheese, oleomargarine, pickled herring, dead insects, and human feces. A species was also reared from decaying vegetables. BIBLIOGRAPHY Banks, N., 1912. — The Structure of Certain Dipterous Larvae with Par- ticular Reference to those in Human Foods. U. S. Dept. Agr., Bur. Ent., Tech. Bull. 22. Hewitt, C. G., 1910. — The Structure, Development and Bionomics of the House Fly, Musca domestica Linn. Howard, L. O., 1910. — A Contribution to the Study of the Insect Fauna of Human Excrement. Proc. Wash. Acad. Sci., vol. 2, pp. 541- 604-. Howard, L. O., and Hutchison, R. H., 1915.— House Flies. U. S. Dept. Agr., Farmers' Bull. 679. Howard, L. 0., and Hutchison, R. H., 1917.— The House Fly. U. S. Dept. Agr., Farmers' Bull. 851. Lallier, P., 1897. — Etude sur la Myase du Tube Digestif chez I'Homme. These Faculte de Medecine de Paris, pp. 120, 1 pi. Lintner, J. A., 1882. — Injurious Dipterous Insects. 1st Rept. Inj. Ins., New York, pp. 168-227, figs. 45-67. (Anthomyiida?.) Lowne, B. T., 1892, 1895.— Tlie Anatomy, Physiology, Morphology, and Development of the Blow-fly {Cnlliphora erythrocephala) . 2 vols., London, 778 pp. 52 pis., 108 figs. Newstoad, R., 1907. — Preliminary Report on the Habits, Life-cycle, and Breeding Places of the Common House Fly {Musca domestica), as Observed in the City of Liverpool, with Suggestions as to the Best Means of Checking Its Increase. Liverpool, 23 pp., 14 figs. Packard, A. S., 1874. — On the Transformation of the Common House Fly, with Notes on Allied Forms. Proc. Bost. Soc. Nat. Hist., vol. 16, pp. 136-150, 1 pi. Patton, W. S., and Cragg, F. W., 1913.— A Textbook of Medical Entomology. Perez, C, 1910. — Recherches Histologiques sur la Metamorphose des Muscides (Calliphora erythrocephala). Arch. Zool. Exp., 274 pp., 16 pis. 152 SANITARY ENTOMOLOGY Riley, W. A., and Johannsen, O, A., 1915. — Handbook of Medical Entomology- Walsh, B. D., 1870. — Larvae in Human Bowels. Amer. Ent., vol. 2, pp. 137-139. (Homalomyia.) CHAPTER X The Control of the House Fly and Related Flies * W. Dxcight Pierce We have now come to one of the greatest problems in Sanitary Entomology ; the control of the treacherous flics that visit our homes but to bring sickness and death. The anti-fly measures may be classed as repressive and palliative, and of course the first are the most impor- tant. THE FLY MUST BE FOUGHT WHILE BREEDING AND BE- FORE IT HAS A CHANCE TO SPREAD DISEASE. Many persons object to the anti-fly-breeding measures because of cost, but no cost is too great if thereby we prevent epidemics and the loss of thousands of lives. Inasmuch as we are dealing with the fly as a municipal, industrial, rural, home, and army problem, the subject will have to be handled topically. REPRESSIVE MEASURES Striking the Source Manure The house fly normally breeds in horse manure, but may also breed in the manure of other domestic animals. It is apparent that this then is the first and most difficult point to strike. The disposal of manure is a matter which must be controlled in all municipalities and wherever there are large congregations of people. For this reason it is an acute problem of army camps and cantonments. In cities it is most acute in stockyards, sales stables, livery stables, and contractor camps. It is a problem on every farm and with every individual who owns a horse, or hog. Chemical Treatment . — Manure is a valuable product and every eff'ort should be made to conserve and utilize it, first rendering it unfit for flies. Realizing this, the United States Department of Agriculture had * This lecture was read August 5, 1918, and has been more or less modified to its present form. 153 154 SANITARY ENTOMOLOGY a long series of careful studies made of many chemicals which might be applied to manure, in order to determine the effects upon the fly larva^, the bacterial activity of the manure, and the fertilizer value of the manure. The results have been published in various bulletins by Plutchison, Cook, and Scales with the principal recommendation in favor of the daily treat- ment of fresh manure with poxcdcred horax at the rate of 1 pound to 16 cubic feet, or 0.62 pound per 8 bushel of manure. This will kill about 90 per cent of the larvae, and is harmless to the manure. Larger amounts, however, may have a deleterious effect. They also found that a water extract of hellebore, prepared by adding ^ pound of powder of hellebore to 10 gallons of water, which after stirring is left for 24< hours, is effective at the rate of 10 gallons to every 8 bushels (10 cubic feet). Likewise a mixture of 1{> pound of calcium cyanamid and l/) pound of acid phosphate to each bushel of manure gives a larvicidal action of 98 per cent. Unfortunately these last two remedies are not available at the present writing. Creosote has been recommended by British authorities, but the investi- gators mentioned above have found a deleterious effect upon the manure. If the primary essential is destruction of fly breeding, and the other chemicals are not available for treatment, creosote treatment is effective, and there will still unquestionably be fertilizing value to the manure. Army sanitarians, especially, can not always use the most approved methods, but must rather obtain immediate results with materials and means at hand. Maggot Traps. — Hutchison discovered an application of the habit of the fly maggots of migrating from the manure piles before pupation, when he developed the maggot trap which consists of a slatted platform over a cement or metal water-filled basin (fig. 32). Such platforms can be built of sufficient size and number to hold the accumulations of manure for a period of about two weeks, after which time it is unfavorable for house fly development. The lai-vae migrate from the pile and fall into the water and drown (plate VIII). Storage in Bins. — The house fly is averse to darkness and various contrivances have been devised for the dark storage of njanure, in pits, tightly closed boxes, windowless rooms, etc. (see plate V). For small stable accumulations, especially in cities, perhaps this furnishes one of the best means of temporary storage. It is a good plan to use fly traps in connection with manure bins (see fig. 33). Stacking. — Manure may be stacked in such a way as to greatly mini- mize, if not entirely prevent fly breeding. A stack built up by the driving of the wagons over the pile and dumping thereon becomes very compact and the internal heating is quite destructive to the fl}^ larvae. The sides of such a pile should be compacted and the loose materials on the ground CONTROL OF THE HOUSE FLY AND RELATED FLIES 155 ■«ij^^'" Fig. 3;^. — A maggot trap for house-fly control. View of the maggot trap, showing the concrete basin containing water in which larvae are drowned, and the wooden platform on which manure is heaped. (Hutchison.) From U. S. Dept. Agr. Bull. ^00, plate 1 (larger), or farmer's bull. 851, fig. 14. (as above). Plate V. — Manure box with fly trap attached. (Bishopp.) 156 SANITARY ENTOMOLOGY thrown onto the pile or raked up and burned. The edges of the pile and the ground around it may be treated with borax or oiled with creosote or crude oil. In Panama it is a custom to set fire to the manure pile and burn it down about a foot, thus covering the entire pile with ash. Broadcasting. — Often on farms it is practicable to take the daily accumulation of manure and spread it over the fields. When the weather is dry, or very hot, or too cold for fly breeding, this method is a very desirable means of handling the manure problem, but the broadcasting of fresh manure on moist ground in cloudy or moist weatlier mav give rise to great quantities of flies unless it is spread very thinly and the larvae are not well matured when the manure is scattered. An illustration of a manure spreader is given in plate \T. An undesirable method of spread- ing manure is shown in plate YIII. Collection of Manure. — It is important that manure be collected and removed from the vicinity of habitations at regular periods, sufficiently frequent to remove the possibility of its becoming a source of fly breeding. In army camps it is imperative that manure be daily removed from all stables, picket lines and stable yards. In cities the ordinary accumula- tions of private stables should be required to be removed once each week, but in the meanwhile it must be either stored in bins or on maggot traps, or daily treated with borax. The accumulations of large stables, livery and feed stables, stockyards, etc., should be required to be removed daily. We may obtain some of our best illustrations of the proper handling of manure from army practices followed during the Great War. Army discipline makes it possible, when the command is properly educated to the importance of it, to control the manure problem more effectively than under any other condition on a large scale. Tremendous quantities of manure were produced in cantonments and shipped in car or train loads daily. Most of the larger cantonments that were located in pro- gressive rural sections were able to fann out the manure to individual farmers or to sell to contractors who shipped it by the carload daily and distributed it to the rural population. When unable to do this the army officials were compelled to resort to storage or destruction of the manure as discussed in other paragraphs. Loading platforms for shipment of manure need to be carefully watched and kept under strict supervision. If these platforms are loosely built of framework elevated above the cars, much of the manure falls through the cracks and over the edges, and great accumulations arise at the sides of the tracks and between the tracks. A properly constructed loading platform should have a cement base with the tracks imbedded in the cement and should be daily flooded, the washings being swept into piles and oiled, and burned when dry enough. The writer has found the CONTROL OF THE HOITSP: FLY AND RELATED FLIES 157 Fig. 33. — Use of flytrap in connection with manure bin. A. Block of wood set in ground to which lever raising door is hinged. (Bishopp.) From Farmer's Bull., U. S. Dept. Agr., No. 734, fig. 6. 1^1. All: \'l. — .Manure spreaA ' ^ ^*"*^3*i?^jj^^ ^ / ^HJII^^^^^^^^^Hf « \ Plate X. — Horse bot flies. Fig. 1 (upper). — GfistrophUus intestinalis, the common bot. Fig. 3 (lower). — Oastrophilus haemorrhoidalis, the nose fly. (Dove.) 184 SANITARY ENTOMOLOGY ^M Plate XT. — Phases of the life cycle of hot flies. Fig. 1 (upper right). — Empty eggs of the cattle hot, Hi/poderma Ihwafa. Fig. 3 (upper left). — Eggs of the common horse hot, Gasfrophilus intestinaHn. Fig. 3 (center). — Full grown larva of Hy- poderma lineata. Fig. 4 (lower rigiit). — Empty puparium of Hiipoderma lineala. Fig, 5 (lower left). — Empty puparium of Gastrophilus intestinalis. (Bishopp.) MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 185 Plate XII. — Method of attack by the common horse hot, Gastrophilus intestinalis. Fig. 1 (upper).^ — Eggs on horse's legs. Fig. 2 (lower). — Larvae attached to walls of stomach, showing lesions caused by removed bots in center. (Bishopp.) 186 SANITARY ENTOMOLOGY Plate XIII. — Method of attack by the cattle hot, or heel fly, Ht/poderma lincata. Fig. 1 (upi)er right). — Fly ovipositing on cow's leg. Fig. 3 (upper left). — Portion of cow's back showing larvae, empty holes and pus exudate. Fig. 3 (lower). — Heav- ily infested cow. (Bishopp.) 1 I MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 187 These infestations probably come about through the accidental depositions of eggs on the bodies or clothing of man, especially children. The possibility of this method of infestation is emphasized through the experience of Dr. Glaser, who while studying ox warbles in Germany had a fly deposit an egg on his trousers which in due time hatched and the young larva penetrated the skin of his leg. Later its presence in the oesophageal region was detected by an uncomfortable feeling. The larva apparently passed up the oesophagus and later was extracted at the base of one of the molar teeth. In instances where the Oestrid fly of the genus Gastrophilus attacks man the conditions surrounding the infestation as well as the exact identity of the lai'va are less well understood. It is supposed that the young larvag are in some way brought in contact with the mucous mem- FiG. 37. — Full grown larva of the human hot, Dermatobia homhm. (Drawing by Bradford.) Actual length 14.5 mm. branes of the lips, mouth or eyes and penetrate them, later appearing under the skin and moving about in a manner somewhat similar to Hypoderma. The life history of the species of this genus will be dis- cussed under intestinal myiasis. America. — In America in addition to the Hypodermas we have among the lower mammals dermal myiasis produced by several different species of Ocstrids in the genus Cuterebra. These are most commonly met with in rabbits, squirrels and certain field mice. Usually they appear to cause no serious injury except in the case of one form, which is prone to attack the testicles of squirrels and was given the name of Cuterebra emasculator Fitch (equals C. fontmella Clark). In South America a very interesting and more important form of myiasis in man occurs. This is produced by the Oestrid, Dermatobia hommis (Carl Linne, Jr.) {noxialis Goudot, cyaniventris, Macquart) (fig. 37). This form appears to be normally the parasite of cattle, horses, donkeys and certain wild animals. It is reported as being a serious pest 188 SANITARY ENTOMOLOGY of cattle, in some cases causing the death of many calves, especially when the cutaneous tumors become infested with larvae of Chrysomj'a. The life history and habits of the species have not been fully eluci- dated, although a number of important contributions have been made. It is generally concluded that the infestation of man is brought about in the following indirect but very interesting manner : The eggs of the fly are deposited on the bodies of certain bloodsucking insects, especially the mosquito known as Psorophora lutzi Theobald (JantJiinosoma), or attached to leaves frequented by these insects whence they adhere to them. The eggs are attached vertically on the under side of the abdomen or the legs. The embryos appear to remain dormant thougli fully developed within the egg and when the bloodsucking dipteron finds a host, the heat of the animal or the blood taken up stimulates the larvas to break from the shell and penetrate the skin of the host. Dermal tumors are formed by the larvae, a well-marked hole opening to the outside as in the case of the ox warble. When the grubs become full growni they leave the host, drop to the ground and transform to adults. The period in the host ranges from two to six months. During this time there is more or less inflammation and sometimes acute pain. This form is widely distributed through tropical America. Lieut. L. H. Dunn has recorded cases of apparent transmission of the eggs by ticks. In South America Dr. J. C. Nielson has reported the occurrence of the Anthomyid flies {Mydaea anomala and M. torquens) as producing subcu- taneous tumors in various birds in parts of Argentina, and Dr. C. H. T. Townsend records M. spermophilae as parasitic on nestlings in Jamaica. Europe. — Several cases of dermal myiasis have been reported, espe- cially from Russia. These are attributed to infestations of larvae of Hypoderma and Gastrophilus. The infestation of reindeer in Lapland and farther south in Nonvay by larvae of the Oestrid fly, Oedemagena tarandi Linnaeus, should be mentioned. The infestations are almost analogous to those in cattle caused by Hypoderma. The eggs are laid on the hair during the spring and later the larvae appear in the submucous tissues of the back. As many as 300 have been reported as occurring in a single animal. This same species no doubt infests the reindeer in Alaska and Canada. Africa. — In Africa the outstanding form of dermal myiasis is pro- duced by the Muscid fly, Cordylohia anthropophaga Griinberg, commonly spoken of as the Tumbu fly (figs. 38, 39). The larv^ae are known as "Ver du Cayor." These develop in the skin of man and various other hosts including dogs (probably the preferred host), cats, horses, and other domestic and wild animals. The attack is painful but not serious, though no doubt when numerous specimens are present unpleasant symptoms fol- low. The life history of this form has not been entirely elucidated, but t MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 189 it. is generally believed that the eggs are deposited on the ground in places frequented by hosts and the larvae hatch and penetrate directly through the skin. In some cases it appears that eggs have been deposited on clothing, especially if moist with perspiration. They appear in March ^^fffgg Fig. 38. — Full-grown larva of the Tumbu-fly (Cordylobia cmthropophaga, Griinberg). Ventral view. X 6. (From Austen.) ^=5s^554 F^iG. 39. — The Tumbu-Fly {Cordylobia anthropophaga, Griinberg). Female. (From Austen.) X 6. and diminish until some time in September when they entirely disappear. Experiments conducted by Roubaud indicate that the choice of host depends mainly on body temperature, the high temperature of hogs and fowls being fatal to the larvse. Cordylobia rodhaini Gedoelst is the cause of cutaneous myiasis in the 190 SANITARY ENTOMOLOGY forest regions of Africa. Man is an accidental host, the species normally infesting thin skinned wild mammals. According to Rodhain and Bequaert, who have given much attention to the biologies of this and related species, the eggs are deposited on the ground in the burrows fre- quented by the animals, the larvae hatch out and penetrate the skin when the hosts are lying upon them. The larvoe develop within the host in twelve to fifteen days. The pupal stage, which is passed in the ground, ranges from twenty-three to twenty-six days, the life cycle being about forty days. Another Muscid genus, Bengalia (especially B. depressa Walker) , causes cutaneous myiasis in man in Rhodesia and other parts of Africa. The eggs are deposited on the clothing or person of man and on the hair of animals. Another interesting form is Neocuterehra squamosa Griinberg, which develops in the adipose tissues in the soles of the feet of the African elephant. INTESTINAL AND UROGENITAL MYIASIS There is every reason to believe that myiasis of the intestinal tract and urogenital openings results largely from careless modes of living. The types of myiasis included in this group should not be confused with urogenital myiasis caused by Chrysomya and related forms. A large per- centage of these cases is purely accidental and there is no doubt that a great many larvae are ingested with food which never produce symptoms to attract attention to their presence. Several different families of flies have been recorded as causing intestinal myiasis, one of the most com- mon being the rat-tail larvae of the family Syrphidae. Records of intes- tinal myiasis due to Sarcophagidae are also numerous, but it should be borne in mind, especially with this fly, that there are many opportunities for mistakes. With little doubt, in many instances, the larvae are not passed, but are deposited in the excrement by flies which have the habit of visiting and depositing larvae almost instantly after defecation. The whole group may be subdivided into those forms which are directly parasitic, such as horse bots, and others which are more or less acci- dental. America. — The importance of the horse bots in infesting equines is such that brief discussion is necessary. In this country there are three species, all of which are of considerable economic importance. These are the common horse bot, Gastrophilus intestinalis DeGcer, the chin fly or throat bot fly, G. nasalis Linnaeus and the nose fly, G. liaemorrhoidalis Linnaeus (plates X, XII). These three species are widely distributed throughout the world and were met with as pests in many of the recent war theaters. Certain other species are also present in European and Asiatic countries but these are of less impoi'tance. MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 191 The life history of the common bot fly is about as follows : The eggs are attached to the hairs of the host, mainly on the legs, but frequently on other parts. These are ready to hatch in from nine to forty days. The larva? are removed from the eggs by the biting and licking of the host. The}' take up their abode in the stomach, remaining attached to the mucous coatings of the pyloric end of this organ until fully grown sev- eral months later. They then detach and pass out with the manure, pupate near the surface of the ground and produce the so-called bot flies three to six weeks later. The cycle is completed in about a year. The life histories of the nose fly and throat bot are similar but diff"er especially in the method of oviposition. The fonner deposits its eggs, which are nearly black, on the very minute hairs around the lips. The young larvae gain access to the mouth and develop as in the common bot fly, but before passing out they usually catch hold of the mucous membrane of the rectum and are often seen protruding from the anus a few days before dropping. The annoyance produced by the oviposition of this fly is very severe. The throat bot deposits its eggs mainly under the jaws and the larvae are often found in the duodenum and also attach in the stomach. In addition to the annoyance produced at the time eggs are deposited, heavy infestations in the stomach interfere with digestion and cases are recorded where the larvae caused death by stopping the pyloric opening. The irritation of bots, which may be present in numbers exceeding 1,000, must be detrimental to the host. The throat bot also attaches in the pharynx in its early stages and is accredited with causing the death of animals from this habit. Cases of dermal myiasis in man attributable to these species have already been mentioned. European writers have also reported the occur- rence of larvae of Gastrophilus in the eye of man. Passing to those forms w^hich are more or less accidental, the Sar- cophagidae demand first attention. Hasseman has reported a case in which an entire family was infested with the larvae of Sarcopliaga haemor- rhoidalis, the maggots being passed in considerable numbers during warm weather. Numerous other similar instances have occurred and in prac- tically every instance they are traceable to leaving foods exposed to flies between meals. Since the Sarcophagids deposit living larvae on meats, etc., they may be easily overlooked. Cases of intestinal myiasis due to Eristalis larvfe are common in this country. A good summary of these cases has been made by Hall & Muir. it appears that they sometimes give rise to acute colicky pains but no serious symptoms. As is well known, the rat-tail larva* arc to be found in decaying vegetation and in water, and the source of infestation must be through the swallowing of uncooked and poorly cleaned food such as watercress and lettuce, and the drinking of unclean water. The follow- 192 SANITARY ENTOMOLOGY ing species have been recorded in this connection : Eristalis tenax Lin- naeus, E. arhustorum Fabricius, E. dimidiatus Wiedemann, and Heloph- ilus pendulinus Meigen. The cheese maggot or skipper Piophila casei Linnaeus, is referred to in a number of instances as tlie cause of intestinal myiasis, often pro- ducing intense colic, and this form has also been recorded from the nose. On account of the common habit of this fly of depositing its eggs in cheese and smoked meat, it is no doubt often eaten in considerable num- bers and the cases where it gives trouble must be comparatively few. This insect passes its complete life cycle in the foods mentioned above, usually attaining the adult stage in about three weeks. It is world-wide in distribution. Species of Muscina, especially M. stabulans Macquart, have been met with frequently in cases of intestinal myiasis, especially in Europe. Mydcea vomiturationis Robineau-Desvoidy is charged with a case of fatal intestinal myiasis. Hydrotaea meteorica Linnasus, a fly probably normally predaceous in the larval stage, has been found to produce intestinal myiasis, in which case blood is sometimes passed accompanied with severe pain. Larvae of the common house fly have been passed in living condition, sometimes preceded by pain. Most of these cases have been in infants and the larvae no doubt usually gain access through the anus. These cases usually result from improper care. The cluster fly, Pollenia rudis Robineau-Desvoidy of the family Muscidae, has been reported in a case of intestinal myiasis. It is difficult to see how this form could gain access to the human alimentary tract since it is normally found only as a parasite of earthworms. In certain parts of tropical America and the West Indies, India, Cey- lon, and the Malay States, the small Phorid, Aphiochaeta ferruginea Brunetti, has been found infesting the human intestinal canal in many instances. Brunetti states that specimens of this fly were sent to the Indian Museum by Crombe with a statement that "eggs, grubs, and flies were all voided together." This occurrence, together with observations made by Baker and reported by Austen, indicate that the flies are capable of living and depositing eggs in the human intestines. This is also sub- stantiated by the fact that larvae of this fly may be passed with excre- ment for as long as a year with symptoms similar to those of beri-beri. Other members of the family Phoridae have been found in human corpses buried for two or more years ; living larAVT, pupae, and adult flies being found together. Aphiochaeta ferruginea breeds in excrement and often frequents various foods including fresh meat. It also breeds in carrion. Its small size enables it to pass through ordinary screen wire and thus increases its potentialities for producing disease. MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 193 The AnthomA'id flies of the genus Fannia have been recorded as caus- ing serious gastric disorders. Among the symptoms are abdominal pains, nausea, and vomiting, and sometimes vertigo, headache, and bloody diar- rhea. Fannia canicularis (plate VII, fig. 3; text figs. 14-16), commonly called the lesser house fly, and Fanma scalaris (text figs. 17-19) are widely distributed and breed in various types of decaying vegetable mat- ter and excrement. We find that the larvae will feed upon and penetrate meat, and they may attack the living tissues to some extent. In the urogenital infesting group the above-mentioned species of Fannia, which are also known as the latrine flies, figure most prominently. These species are rather strongly attracted to human excrement, espe- cially urine. This habit is undoubtedly responsible for the infestation of the genitalia. Such infestations must certainly be attributed to the exposure of the genitals in sleep by drunken or careless persons, or occa- sionally infants. Robineau-Desvoidy has reported a case in which an Oestrid larva was passed from the bladder by a woman. Kollar has re- ported the occurrence of a large number of larvae of the common house fly in the vagina of a diseased woman. Chevral has brought together a number of records of cases of myiasis of the genitalia. Europe. — Nearly all the above-mentioned forms are to be encoun- tered in parts of Europe. In the Mediterranean countries one would expect to find a greater number of forms leading to these types of myiasis. Africa. — Several of the previously mentioned forms occur in Africa. The Oestrid larva, Pliaryngoholus africanus Brauer, commonly attaches to the walls of the esophagus of the African elephant, and an Oestrid of the genus Cobboldia (C loxodontis Brauer and C. chrysidiformis Rodhain and Bequaert) are found in the stomach of the African ele- phant, and C. elephantis (Steel) Cobbold, attacks the Indian elephant in a similar way. Species of Girostigma in the same family infest the stomach of the Rhinoceros. Anthomyia disgordiensis is said to be not infrequently passed from the intestines of man in Angola. FORMS PRODUCING MYIASIS IN HEAD PASSAGES All of the species included in this group are normally parasitic on animals, and infestation of man, altliough not uncommon, must be con- sidered accidental. In the lower animals the attack of these larvag is often quite injurious tliough not usually fatal in itself. In man the principal injury sustained is in the eff'ects on the eye when it happens to be attacked. America. — In the United States as well as in all parts of the world, the sheep head maggot, Oestrus oris Linnaeus, is the most important 194 SANITARY ENTOMOLOGY form in this group. The fly deposits living larvae on the nose of the sheep and the young maggots work upward through the nasal passage, later entering the head sinuses. The maggots arc (juite spinv and hence must produce much irritation. They appear to subsist upon the mucous secretions of the head cavity. Several months are passed in the host and the larvas drop out and pupate in protected places on the ground, producing flies a few weeks later. I know of no record of the attack of man by this species in the United States, but in other countries it frequently attacks the eyes, nose, mouth, and ears. The fly deposits the larvae so quickly that there is little opportunity to protect one's self. The most serious symptoms develop from infestation of the eye where larvse produce severe conjunc- tivitis and in some cases, if not promptly removed, cause the loss of sight. In this country the Cervidae (deer, elk, etc.) are attacked by Oestrids of the genus Cephenomyia (C. pratti Hunter, and C. phobifer Clark). The larv-^aB of these flies are found in the head passages, pharynx, and even in the lungs. Europe. — The sheep head bot has a wide distribution in Europe and is responsible for loss among sheep and infestation of man as above described. Probably the most important species in this group is Rhinoestrus purpureus Brauer, which ' is a very common parasite of the horse in Russia, Hungary, and Italy. This form is also responsible for cases of myiasis in the eyes of man, the attack apparently being similar to that of Oestrus ovis. Horses are infested by the flies which deposit lar\'ae in the nose or eyes. They are much annoyed by the deposition of the insect and the larvjE give rise to fits and other symptoms, mistaken for strangles, sometimes resulting in death. The species is also knoAvn to attack the zebra. Cases of the occurrence of this species in the eyes of man have been reported from Jerusalem, and are not infrequent in southern Russia. The reindeer in Europe are subject to the attack of Cephenomyia trompe Linnaeus in a way similar to the infestation of sheep by Oestrus ovis. Nativig reports the finding of as many as 100 larvae in the nasal cavity and larynx of a young reindeer, Africa. — In Algiers, especially, Oestrus ovis is very destructive to sheep and many cases have been reported by the Sergents and others of the infestation of man by this species. The horse head bot, Rhinoestrus ptirpureus, occurs in the Egyptian region. The camels are infested by the Oestrid, Cephalomyia maculata Wiedemann {Cephalopsis titillator Clark). Larvae thought to be Rhinoestrus nasalis are common in the head sinuses of cattle in parts of Africa. MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 195 Many species of Oestrids occur in the head passages of African animals. Rhinoestrus hippopotami Griinberg occurs in the skulls of lii}>popotami and apparently -this species attacks hogs. Tlie genera Gedoelstia and- Kirkioestrus each contain species which infest the head sinuses of African wild niannnals. BLOODSUCKING FORMS This mode of attack is not generally considered myiasis but it seems to have a logical place in this discussion. All of the species having bloodsucking habits developed among tlieir larv?e are to be found in the family Muscidae. Up to the present time there seems to be com- paratively little importance attached to them, although such forms as the Congo floor maggot may be responsible for the introduction of disease germs into man. America. — The only representatives of this group found in North America are Phormia azurea (Fallen) Villeneuve and P. chrysorrlioca (]\Ieigen) Rodhain and Bequaert. The first mentioned species is found commonly in Europe where it was first recorded as feeding in the lai-^^al stage on nestlings of the sparrow and other birds. This same habit has been observed in the United States. The second form, which is quite common in the nests of larks and other birds in the southwestern states, appears to cause a definite dermal myiasis as the larva; are frequently found partially imbedded in the wings, legs and body tissues of fledglings. The fly, Mydaea pici Macquart, is reported as infesting young birds in a similar way in Brazil." Europe. — Phormia azurea (above mentioned) is quite common in the nests of birds in France and P. sordida (Zetterstedt) Roubaud has similar habits. Africa. — The form which is especially interesting and important in this group is the African floor maggot, Auchmeromyia luteola (Fab- ricius). This fly appears to be very closely associated with man. The adults are found in the dwellings and about latrines in tropical and sub-tropical Africa. The eggs are deposited on the dry soil of the floors of native huts, especially under sleeping mats. The larvae come out at night and attack the sleepers, filling with blood in a very short time. The adult is also a blood-sucker. The larval .stage occupies about fif- teen days and the pupal stage about eleven days. The larvae do not burrow into the tissues but simply attack the skin with the mouth hooks and suck the blood. ^ Plath has reported recently on the occurrence in the nest of a robin la/vae of a new species, Phormia mefri/lira Townsend. He also discovered in birds' nests, larvae of a new species of Anthoniyidae, Hi/lemyia nidicola Aldrich. The latter probably feeds on dead birds onlv. 196 SANITARY ENTOJNIOLOGY The related genus Choeroniyia contains three or four species includ- ing C. choerophaga Roubaud and C. boueti Roubaud which occasionally bite man but normally live in the burrows of such hairless animals aS the warthog and ant bear. The habits are similar to the floor maggot. Certain birds are attacked by tlie larvae of Passeromyia heterochaeta Villeneuve in a way similar to that reported for Phormia. This form occurs in Central Africa and also in China. SOME BIBLIOGRAPHICAL REFERENCES Austen, E. E., 1912. — British flies which cause myiasis in man. Repts. Local Govt. Bd. on Pub. Health, and Med., n. s., No. 66, pp. 5-15. Bishopp, F. C, 1916. — Flies which cause myiasis in man and animals. Some aspects of the problem. Journ. Econ. Ent., vol. 8, No. 3, pp. 317-329. Bishopp, F. C, and Laake, E. W., 1915. — A preliminary statement re- garding wool maggots of sheep in the United States. Journ. Econ. Ent., vol. 8, No. 5, pp. 466-474. Bishopp, F. C, Mitchell, J. D., and Parman, D. C, 1917. — Screw-worms and other maggots aff'ecting animals. U. S. Dept. Agr., Farmers' Bull. 857. Carpenter, G. H., and Hewitt, T. R., 1915.— The warble flies. Fourth Rept., Journ. Dept. Agric. & Tech. Instr. for Ireland, vol. 1'5, 30 pp. Chevral, Rene, 1909. — Sur la Myase des voies urinaires. Arch, de Parasit., vol. 12, pp. 369-450. Cooper, W. F., and Walling, W. A. B., 1915. — The effect of various chemicals on blow-fly. Annals of Applied Biology, vol. 2, Nos. 2 and 3, pp. 166-182. July. Coutant, A. F., 1916. — The habits, life-history, and structure of a blood- sucking Muscid larva. Journ. Parasit., vol. 1, pp. 135-150, 7 figs. De Stefani, T., 1915. — Notes on myiasis in animals and man. II Rin- novamento Economico-Agrario, Trapani, vol. 9, Nos. 5 and 6, May- June, pp. 89-92, 110-113. Dove, W. E., 1918.- — Some biological and control studies of GastropJiilus haemorrhoidalis and other bots of horses. U. S. Dept. Agr., Bull. 597. Dunn, L. H., 1918. — Studies of the screw-worm fly, Clirysomyia macel- laria F., in Panama. Journ. Parasit., vol. 4, No. 3, pp. 111-121. Foreman, F. W., and Graham-Smith, G. S., 1917. — Investigations on the prevention of nuisances arising from flies and putrefaction. Journ. Hyg., vol. 16, No. 2, pp. 109-226. MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 197 Froggatt, W. W., 1915. — Sheep-maggot flies. Dept. Agric. New South Wales, Fanners' Bull. 95, 52 pp. Froggatt, W. W., and Froggatt, J. L., 1917. — Sheep-maggot flies, No. 3. Dept. Agr. New South Wales, Farmers' Bull. 113, 37 pp. Froggatt, W. W., and Froggatt, J. L., 1918. — Sheep-maggot flies. No. 4. Dept. Agr. New South Wales, Farmers' Bull. 122, 24 pp. Fuller, C, 1914. — The skin maggot of man. Agric. Jouni. Union S. Africa, vol. 7, No. 6, pp. 866-874. Glaser, Hans, 1912-13. — Uber Dasselfliegen mit des ausschusses zur Bekampfung der Dasselfliege. Nos. 3, 4, 5. Hadwen, S., 1915. — A further contribution on the biology of Hypoderma Imeatum and Hypoderma bovis. Parasit., vol. 7, pp. 331-338. Hadwen, S., and Bruce, E. A., 1916. — Obser\^ations on the migration of warble larvae through the tissues. Health of Animals Branch, Dept. Agr. Canada, Sci. Ser., Bull. 22, pp. 1-14. Hall, C. M., and INIuir, J. T., 1913. — A critical study of a case of myiasis due to Eristalis. Arch. Internat. Med., vol. 11, No. 2, pp. 193- 203. Hewitt, C. Gordon, 1912. — An account of the bionomics and the larv* of the flies Fannia canicularis L. and F. scalaris Fab., and their rela- tion to myiasis of the intestinal and urinary tracts. Repts. Local Govt. Bd. on Pub. Health and Med. Subjects, n. s.. No. QQ, pp. 15-22. Keilin, D., 1917. — Recherches sur les Anthomyides a larves carnivores. Parasit., vol. 9, 125 pp., 11 pi., 41 figs., May. Knab, F., 1916. — Egg disposal in Dermatohia liominis. Proc. Ent. Soc. Wash., vol. 18, pp. 179-183. Lallier, P., 1897. — Etude sur la myasc du tube digestif chez I'homme. These F'aculte de Medecine de Paris, 120 pp., 1 pi. Lefroy, H. INI., 1916.- — The conti-ol of flies and vermin in Mesopotamia. Agric. Journ. of India, vol. 11, pt. 4, pp. 323-331. Lutze, 1915.— Diseases caused by flies and their larvae. Deutsch. Tierarzt. Wochenschr. Hanover, vol. 23, No. 46, pp. 395-397, 7 figs., Nov. Marlatt, C. L., 1897.— The ox warble. U. S. Dept. Agric, Bur. Entom, n. s., Cir. 25, 10 pp. Neiva, Dr. A., and De Faria, G., 1913. — Notes on a case of human myiasis caused by larvae of Sarcophaga pyopliila, sp. n. Mem. Inst. Oswaldo Cruz, vol. 5, No. 1, pp. 16-23. Nielson, J. C, 1913. — On some South American species of the genus Mydaea, parasitic on birds. Vidensk. Meddell. fra Dansk naturh. Foren., vol. 65, pp. 251-256, 4 figs.. May. Palazzolo, G., 1916. — Hypoderma bovis and the fly Dermatobia noxialis 198 SANITARY ENTOMOLOGY or cyaniventris of Brazil. Nuovo Ercolani, Turin, vol. 21, Nos. 26- 27, pp. 433-437, Sept. Patton, W. S., and Cragg, F. W., 1913.— A Textbook of Medical Entomology. Phelen, J. M., 1917. — U. S. Army Methods of disposal of camp refuse. Amer. Joura. Pub. Health, vol. 7, No. 5, pp. 481-484, May. Portchinsky, I. A., 1913. — Oestrus ovis L. ; its life history and habits, the methods of combating it and its relation to human beings. Mem. Bur. Ent. Sci. Comm. Cent. Bd. Land Admin, and Agric, St. Peters- burg, vol. 10, No. 3, 63 pp., 28 figs. Portchinsky, I. A., 1914. — A review of the spread of the chief injurious animal pests in Russia in 1913. Yearb. Dept. Agric. for 1913, Petrograd, 14 pp., 4 figs. Portcliinsky, I. A., 1915. — Rhinoesirus pur jm reus Br., a parasite of the horse, injecting its larvjp into the eyes of men. Bur. Ent. Sci. Comm. Central Bd. Land Admin, and Agric, Petrograd, vol. 6, No. 6, 42 pp., 9 figs., 1 pt. Portchinsky, I. A., 1916. — Wohlfahrtia magtiifica Schin., and allied Rus- sian species. The biology of this fly and its importance to man and domestic animals. ]Mem. Bur. Ent. Sci. Comm. Agric, Petrograd, vol. 11, No. 9, 108 pp., 39 figs., 2 pi. Rodhain, M. J., 1915.— On the biology of Cordylohia rodhaini Gedoelst. C. R. Hebdom. Ac. Sci., Paris, vol. 161, No. 11, pp. 323-325. Rodhain, J., and Bequaert, J., 1915. — On some Congo Oestrids. Bull. Soc Path. Exot., Paris, vol. 8, No. 9, pp. 687-695. Rodhain, J., and Bequaei't, J., 1916. — Materials for a monograph on the parasitic Diptera of Africa. Bull. Sci. France et Belgique, Ser. 7, vol. 49, No. 3, pp. 236-289, 14 figs., April 29. Rodhain, J., and Bequaert, J., 1916. — Materials for a monograph on the parasitic Diptera of Africa. Second Part. A revision of the Oestrinae of the African Continent. Bull. Sci. France et Belgique, Ser. 7, vol. 50, Nos. 1-2, pp. 53-165, 29 figs., 1 pi., November 25. Rodhain, J., and Bequaert, J,, 1919. — Materials for a monograph on the parasitic Diptera of Africa. Third Part. Bull. Sci. France et Belgique, vol. 52, No. 4, pp. 379-465, 21 figs., 3 pis. Roubaud, E., 1913. — Researches on Auchmeromyia, Calliphorine flies with blood-sucking larvae from tropical Africa. Bull. Sci. France et Belgique, Ser. 7, vol. 47, fasc. 3, pp. 105-202, 2 pis., 32 figs., June 24. Roubaud, E., 1914. — Stomach- and sinus-inhabiting Oestrids of French West Africa. Bull. Soc Path. Exot., vol. 7, No. 3, pp. 212-215, March 11. I MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 199 Roubaud, E., 1914. — Studies of tlic parasitic fauna of French West Africa. Part I. The producers of myiasis and simihir disorders in man and animals. Paris: Masson & Co., 251 pp., 4 coL pis., 70 figs. Roubaud, E., 1915. — Muscids, the larvae of which bite and suck blood. C. R. Soc. Biol., Paris, vol. 78, No. 5, pp. 92-97, 2 figs., March 19. Sambon, L. W., 1915. — Observations on the life history of Dermatobia hominis. Rept. Adv. Com., Trop. Diseases Research Fund for 1914, London, pp. 119-150. Sergent, Ed., and Sergcnt, Et., 1913.— "Tamne"— the "Thimni" of the Kabyles — the human myiasis of the Taureg ]\Iountains in the Sahara, caused by Oestrus ovis. Bull. Soc. Path. Exot., No. 7, pp. 487-488, July 9. Ward, Henry B., 1903. — On the development of Dermatobia hominis. Rep. from the jNIark Anniversary Volume, Article XXV, pp. 483-512, plates 35-36. CHAPTER XIII Myiasis — Its Prevention and Treatment ^ F. C. Bishopp In the preceding lecture the habits and biologies of the various species concerned in myiasis in man and animals have been briefly outlined. An accurate knowledge of the species concerned and a good general idea of its biology and habits are essential to the proper handling of myiasis, especially when the cases are numerous. In discussing control of the flies concerned and tlie treatment of cases the same general grouping as made in the previous lecture will be fol- lowed. Wliere various species of Mow flies and related forms are numerous, immediate steps should be taken to determine the source of supply and energetic measures applied to prevent it without waiting for the appearance of cases of myiasis in man or animals. TISSUE-DESTROYING FORMS Prevention of Breeding. — Since practically all species concerned in the production of this form of myiasis develop ^\^thin decaying animal matter, first attention must be given to this point. Burning of Carcasses. — The carcasses of large animals are sources of tremendous numbers of flies. We have estimated that over a million specimens may be produced in the body of one cow. Nothing is as satis- factory as complete destruction of carcasses by burning. This not only prevents fly breeding but reduces the chances of the propagation of such diseases as black-leg, anthrax and tuberculosis. Carcass burning can be carried out under practically any condition with which the sani- tary entomologist will have to deal and the process is by no means difficult nor expensive. Various methods have been advocated but we have found nothing equal to the following: Dig a trench about eighteen inches wide, twelve or fourteen inches deep and equal to the length of the carcass to be burned (plate XIV). This trench should be dug with the direction of the prevailing wind and along the back of the car- cass ; fill the trench with wood and then turn the animal over on top of it. Start the fire in the windward end of the trench and no further ^This lecture was presented November 18, 1918, and distributed January 20, 1919. iOO MYIASIS— ITS PREVENTION AND TREATMENT 201 attention is necessary for several hours, when tlie extremities ina^^ be piled in the center to complete burning. The placing of wood on top of the carcass and addition of wood after the fire has started are unnecessary. About one-quarter of a cord of wood is adequate, and where wood is scarce, burning may be accomplished by using crude oil. Of course a few sticks of wood beneath the carcass will help hold the heat but this is not necessar3\ Ten to twenty-five gallons of crude petroleum are sufficient. The odor from carcass burning is not very objectionable, especially if the animal is destroyed soon after death. In cities it is usually feasible to have all large carcasses promptly Plate XIV. — Trench prepared for burning carcass. ( Bishop]). removed and effectually destroyed by commercial rendering and fertilizer plants. These establishments should be subject to sanitary inspec- tion. Carcass Burial. — Burial is generally unsatisfactory, especially if bodies are well infested with maggots. We have found that at least twenty-four inches of finely packed earth are necessary to prevent their escape. The free use of quicklime on the body after it has been placed in the grave helps to destroy the maggots and reduce chances of disease spread. We have not yet undertaken experiments with the treatment of carcasses before burial with creosote oil, but judging by results obtained from treating those on the surface, this should be a good method of destroying larvae, reducing odor and killing disease organisms. 202 SANITARY ENTOMOLOGY Treating with Chemicals. — Nearly all maggots of this class of flies are exceptionally resistant to the action of chemicals. We have found some to survive submergence in very destructive insecticides. Foreman and Graham-Smith, working in England, have found that creosote oil, which is one of the higher distillates from coal tar, is quite efficacious in the treatment of carcasses. Two things are accomplished— the majority of the lan^ae are actually hit by the spray and destro^'ed and decomposi- tion is practicall}'' stopped with corresponding reduction in odor. In recent experiments conducted at the Dallas Laboratory, we have found that several American makes of creosote oil are excellent for this pui-pose. Small carcasses thoroughly sprayed before infestation takes place will remain free from infestation, the flies being repelled by the substance and odor practically prevented. The carcass usually shrinks and as- sumes a mummified condition. Such creosote oils are manufactured by a number of concerns and usually sold at prices ranging from sixty- five cents to one dollar per gallon, according to the per cent of coal tar acids contained. Rather high percentage of these ingredients (at least 12 per cent) is best. Since direct sunlight is a powerful destructive agent in the semiarid and arid regions, if burning cannot be accomplished, tlie carcasses should be left in the most exposed place possible- — not in a gully under shade as is usual. This will often result in about 85 per cent control. Disposition of Garbage. — The question of garbage disposal has been discussed briefly in other lectures (Chapters X, XI). Nearly all gar- bage is attractive to blow flies as well as other forms and the bone and meat scraps become infested. Where incineration is practicable it is most desirable. When fed to hogs the bones should be picked out and placed in a screened compartment or treated with borax or creosote oil. Destruction of Flies. — In general the destruction of flies should be considered as secondary to the elimination of breeding places, but under certain conditions this method of attack has its place. Traps. — Various types of traps have been devised for destruction of flies but a careful comparison of many diff^erent forms in experiments car- ried out at the Dallas Laboratory shows that there is much difl'erence in their efficiency and also that some minor changes in the construction of a trap may greatly improve the size of the catch. As a result of these experiments the fly trap described in Farmers' Bulletin No. 734* is being recommended by the Bureau. This trap appears to be the best all round form for catching both house flies and blow flies. Of course the framework of the trap need not be made of hoops and barrel heads, as suggested in that bulletin, although those prove very satis- factory. The essential principles are to have the high cone, comparatively MYIASIS— ITS PREVENTION AND TREATMENT 203 large opening at the top of tlie cone, screened area over the cone to admit light from above, screened sides so as not to cast shadow around the bait, and legs about one inch higli. The tent traps are not as efficient as the cone traps and this inefficiency is especially marked in some makes of traps now being furnislicd the Army, which are built with a broad bottom on either side of the tent. This repels the flies to such an extent as to make the traps almost worthless. For blow flies this dark- ened area is not so objectionable as for the house fly. While not strictly a trap, the method of covering carcasses with burlap as recently sug- gested by Froggatt in Australia may be of value. Four stakes are driven into the ground around the carcass, and the tops of these are connected with a heavy wire. A canopy is then put over the stakes, brought to the ground and dirt piled on the edges. When the flies emerge they are imprisoned and soon die. If the canopy is not sufficiently large, there is danger of many escaping through the migratory habit of the larvae. Kind of Bait to Use. — This point has been discussed in a previous lecture. Animal matter is best for blow flies, and the packing-house ref- use known as "gut slime" is best of all. It is removed from intestines when sausage casings are made. Good baits and proper attention to kill- ing and rebaiting are essential to best results. Poisons. — It is possible to destroy large numbers of flies by means of poisoned baits. Arsenic solution (made by boiling arsenic in water) mixed with defibrinated blood, gut slime, or some other attractive bait will kill large numbers. This bait may be placed in covered containers to prevent dilution by rain. Cobalt may be substituted for arsenic. When carcasses can not be burned, Froggatt has advocated slashing them and spraying with arsenic solution. This poisons large numbers of flies and maggots and reduces the attractiveness of the carcass ; so much so, in fact, that birds and animals will not touch it. Avoidance of Attack on Man. — To prevent fly attack it is necessary to have wounds promptly and properly dressed. Man should avoid exposure by sleeping in the open during hot weather, especially if there is any trouble from catarrh or nose bleeding. Properly screened hos- pitals are of much importance and individual blow flies found within should be promptly killed. Avoidance of Attack to Animals. — In preventing screw-worm attack in cattle and other livestock, there are several important points to be considered. Breeding should be done so as to have calves come during fall, winter or early spring months. Branding and surgical operations should also be done out of screw-worm season. Care should be taken to avoid mechanical injury to stock. As the screw-worm flies are worst in brushy pastures, clearing out all underbrush will be found beneficial. Since many cases develop from infestation of ticks and mange, the de- 204 SANITARY ENTOMOLOGY struction of ticks and mange mites on animals is important. Care should be taken to guard against extensive saddle or harness sores on army animals. Methods of preventing blowing of* wool on sheep hardly need to be discussed fully here. Shearing early in the spring, avoiding the soiling of wool, raising hornless breeds and the crutching, that is clipping the wool at the vent and behind the hind legs greatly reduces infestation. Treatment of Infestations in Man. — Nasal myiasis is the most dif- ficult to handle. The larvae should be removed mechanically as far as possible. A number of different treatments have been resorted to, the administration of chloroform into the nose being the most used. After all larva? have been taken away, it is usually necessary to exercise care to prevent breaking of blood vessels which are frequently greatly exposed by destruction of the surrounding flesh. In most wounds the larvae are quite easily removed. Of course the details of the care of the patient are to be determined by the physician in charge. Treatment of Woumds in Animals. — Chloroform is the most generally used of all reagents and is usually satisfactory. The chloroform is poured directly into the holes and the wounds closed up. This benumbs the larvae so that they can be taken out with a forceps. Carbon tetra- chloride is also satisfactory for this use and considerably cheaper. After the larva? have been taken out antiseptic astringent dressing should be applied and pine tar or pine oil and vaseline applied to the outside to repel flies. Oil of camphor is an excellent fly repellent and aids in the healing process. Bleeding wounds should be dusted with tannic acid before applying the repellent. SUBDERMAL MIGRATORY SPECIES The reduction of the number of ox warbles in cattle is important from the standpoint of the raiser as well as to lessen the chances of infestation of man and horses. The most feasible method yet devised consists in the squeezing out of the larvjc from the backs of the animals after they have formed the subcutaneous tumors. This should be done at intervals of about three weeks, all animals being gone over carefully. The period for beginning extraction varies according to latitude from October 15 to March 1. The question of controlling Dermatohia hominis in tropical America, and also its African analogue, Cordylohia anthropophaga, has not been sufficiently worked out to make satisfactory recommendations. No doubt where livestock are under control, systematic extraction will reduce the number of these, both in animals and man. When humans become in- fested it is usually advisable to allow the larva to become stationary and MYIASIS— ITS PREVENTION AND TREATMENT 205 then remove it through the hole in the skin. It may be necessary to en- large the hole to get it out more easily. In tlie case of the American forms the bite from various bloodsucking Diptera should be prevented as far as possible. Having the body well protected with clothing will also probably reduce injury from both of these species. On account of the probability that some of the African parasites of this class deposit eggs on exposed clothing, especially if wet with perspiration, this should be guarded against. SPECIES CAUSING INTESTINAL AND UROGENITAI. MYIASIS Control of Truly Parasitic Species. — In Animals. — There are three principal methods of attack against the bots of horses. The de- FlG. 40. — Nose protection for horse against attacks of the nose fly, Qastrophilus haemorrhoidalis. (Dove.) struction of eggs will accomplish much good in the case of Gastrophilus intesfinalis and is applicable to some extent to G. nasalis, but apparently can not be practiced in G. haemorrhoidalis . Dove has found that the common practice of washing the legs of horses ^vith kerosene oil has but little beneficial effect. The creosote derivatives containing about two per cent phenols destroyed the eggs readily. A miscible creosote com- pound reduced with water to this strength and applied with a rag or brush at the time the horses are groomed will destroy practically all eggs present. Such treatment repeated weekly should accomplish almost complete control. In this way horses and mules may be kept practically free from infestation. Of course the grooming itself will tend to hatch 206 SANITARY ENTOMOLOGY eggs and get rid of larvae. Clipping of the hair oh the legs has also been recommended but is not entirely satisfactory. Dove has experi- mented with certain halter devices for the protection of horses in pas- tures and also with various types of guards to be used on horses in harness to prevent the attack of the nose fly (fig. 40). In the first case he used a halter, from whi(^i is suspended a box-like arrangement tliat covers the nose when the horse has its head up, but permits of grazing and drinking. A canvass extends back under the jaw to prevent deposi- tion of eggs by the throat bot, and of course the covering of the mouth prevents the ingestion of eggs of the common bot. The main difficulty has been the production of a durable device of this kind. The nose fly attack is best prevented by a rectangular piece of belting being suspended from the bit rings immediately below the lips, when horses are at work. The internal treatment of infested animals with carbon disulphide has been found to be very effective if properly done. Three three-dram doses at hourly intervals are given in capsules succeeding a period of starvation and followed by a purgative. Pre: ention of Attack in Man. — The reduction of the number of hots by treatment of the lower animals will greatly reduce the chances of in- festation in man. Care should be taken not to ingest eggs or larva; when infested horses are being clipped or groomed. Prevention of Attack by Other Forms. — This group includes those species accidentally infesting man such as the ]Muscids Mnsca domestica, and Muscina spp., Fannia, and Syrphus flies. Destruction of Breeding Places. — Since most of these forms are breeders in excrementitious matter and decaying vegetation, the proper care of manure of all kinds is important. This has been discussed in other lectures. Since some of the species, especially Fannia, breed in accumu- hitions of decaying vegetation such as straw, roots, etc., these should receive attention, especially when close to camps. Destruction of Flies. — The use of traps is eff*ective against most of the species concerned except the small Phorids and Syrphids whicli are not inclined to enter traps baited with usual baits. Poison baits and fly paper will also destroy some species other than the house fly. Food and Water. — The careful preparation of uncooked food such as cress, lettuce, etc., is important. No doubt many of the cases of infes- tation by Fannia and Eristalis have been due to the eating of improperly washed foods of this kind. Drinking promiscuously from streams and pools should not be permitted. During the Great War the provision of a good water supply for the men received first consideration. Of course this is im})ortant to prevent infestation with various disease organisms. Distillation, filtration and chlorination are the preferred methods of MYIASIS— ITS PREVENTION AND TREATMENT 207 producing pure water. Where it is essential that water must be taken from streams care should be exercised not to drink near vegetation. Use of Screens. — Proper screening of houses will do much to protect foods after preparation from infestation, although some of the small forms can not be kept out in this wa}'. A coarser mesh than 16 per inch should not be used. Tlie use of screened toilets of course can not be too strongly emphasized. Cleanliness and Careful Habits. — Many infestations of the digestive system and genitalia could be avoided by not sleeping in unscreened places in an exposed condition. Prompt attention to infants is important. SPECIES INFESTING HEAD PASSAGES Infestations in Animals. — The parasitic forms are very difficult to control and no very satisfactory control measures have been devised. Nearly all of the recommendations made are of little value. Some of these consist of the use of repellents in the case of sheep to protect them from infestation by Oestrus ovis. Pine tar is most frequently used and this is applied by the sheep themselves. Holes in logs are used for salting and the sides are smeared with tar. The provision of plowed furrows where the sheep can protect their noses probably gives some relief. For very valuable animals screened pens are no doubt warranted, the animals being placed in these during the portion of the day when the flies are most active. There seems to be considerable difference in eff'ect of attacks on breeds. Attempts to remove the larvae from the nose by causing sneezing or with fumigants are more likely to drive the larva3 deeply into the head than to remove them. Trepliining the skull and removing the larvae in that way may give some relief but is usually not advisable as other infestations are likely to follow and all the grubs can not be reached. Destruction of adults has been advocated and is especially applicable to plains areas, as in such places flies are inclined to congregate on any objects which extend well above the ground. The flies assemble on such objects and remain there except during the warmer part of the da}'^ and many can be killed. ]\Iany of the control measures suggested for the control of the sheep bot can be used against the horse infesting species, Rhvnoestrus pur- pureus. It might also be possible to utilize nmzzles similar to tliose advo- cated for the horse bots to protect against infestations from tliis species. Infestations in Man. — Infestations of man are so infrequent that pre- ventive measures need receive little attention. Where such infestations either by the sheep head maggot or horse head maggot arc common the use of nets on tlic hats similar to those used by apiarists would give protection. jMedical attention should be given promptly for re- moval of larv,T, especially if in tlie eye. 208 SANITARY ENTOMOLOGY BLOODSUCKING SPECIES In Birds. — Since these dipterous parasites are often highly injurious to birds, and especially to certain beneficial varieties, control measures should be considered although nothing has been done along this line. In the Southwest it is stated that the mortality among birds is very high ownng to these parasites. Possibly trapping of the adults in connection with the control of other destructive species would be feasible. In Man. — The Congo floor maggot is the only species in this group requiring special attention. The use of beds instead of sleeping mats laid directl}'^ on the floor will give immediate relief. Wiiere beds are not at hand hammocks may be used. The avoidance of sleeping in huts is advisable. Thorough cleansing and disinfection of the floor should destroy many maggots and the elimination of cracks in the dirt will check their breeding. Where sleeping mats are used by the natives they should be sunned and aired frequently. It is said that the maggots are carried from one hut to another in these mats, so that moving the place of abode does not eliminate the trouble. CHAPTER XIV Diseases Transmitted by Bloodsucking Flies-"^ W, Dwight Pierce As stated before it was necessary to discuss the transmission of diseases by flies in three lectures, non-bloodsucking flies, mosquitoes and other bloodsucking flies. This is therefore the second lecture on fly- borne diseases, and embraces quite a diff'erent category of diseases. For convenience of reference and study it will be likewise handled from the standpoint of the organism transmitted. The most important volume on the subject of this lecture is by Hindle. PLANT ORGANISMS CARRIED BY BLOODSUCKING FLIES Thallophyta: Fungi: Schizomycetes: Bacteriaceae Bacterium tidarense McCoy and Chapin, the causative organism of a RODENT PLAGUE, is probably normally carried by fleas, but Wayson records some interesting experiments with the stable fly, Stomoxys cal- citrans Linnaeus. He found that a fly after biting an acutely diseased guinea pig eight times, if applied to a healthy animal within an hour, will cff'ectively transmit the disease to the healthy animal and cause its death in five to nine days. Washings of the flies in normal salt solution, and also washings of the flies slightly crushed, when injected subcutaneously will produce similar results. The transmission by bites occurs only from those animals having an advanced stage of the bacteremia, as indicated by their death within 24 to 48 hours after the fly feeding. The flies have not been proven infective as long as 24 hours. This same organism has been isolated from cases of DEER FLY FEVER or PAHVANT VAL- LEY PLAGUE in Utah by Francis (1919). The disease is local and one case in 1919 was fatal. The fever, lasting from 3 to 6 weeks, is said to be initiated by the bite of deer flies (Chrysops). Bacterium anthracis Davaine, the causative organism of ANTHRAX or charbon, can be carried by bloodsucking flies. Nuttall (1899) cites many early references to the role of bloodsucking flies in the transmis- ^This lecture was presented Octobe'* 7, 1918, and distributed October 19. It has been somewhat modified for the present edition. 209 210 SANITARY ENTOMOLOGY sion of anthrax, the earliest being by Montfils in 1776. Hintermayer (1846) studied an epidemic whicli raged among the deer in the Park of Duttstein. The horse flies, Tahanus bovinus Loew, Haemotopota plu- vialis (Linnaeus), and Chrysops coecutiens (Linnaeus) assembled usually in thousands on the carcasses of the fallen animals and sucked the pro- fluvia which escaped from tlie mouth, nose, and vent. Leaving the bodies they immediately sought the healthy animals, thrust their proboscides soiled with the virus into the skin and in this way inoculated the poison of the disease. Mitzmain (lOl-i) proved that Tahanus striatus Fabricius and the stable fly, Stomoxys calcitrans Linnaeus, can transmit the disease by their bites. Schuberg and Kuhn (1912) transferred anthrax infection from a cadaver to a living animal through the bite of Stomoxys cal- citrans. Morris (1918) working on anthrax in Louisiana proved that the horn fly Lyperosia irritans Linnaeus (Haemafobia) when biting an in- fected guinea pig four hours or less before its death and up to fifteen minutes after death can transmit infection. One hundred and eighty- four experiments on different guinea pigs were made during these time limits and infection was conveyed in 34 per cent of the cases. Forty experiments outside of these time limits were unsuccessful. One out of two tests with the flies feeding on an infected sheep thirty minutes before death yielded infection in a guinea pig, and all tests of biting in the quar- ter hours before and after death of the sheep yielded infection in guinea pigs- He also tested a species of Tahanus and proved transmission in 40 per cent of 70 cases in whicli the flies bit between four hours before death and five minutes after death. Virulent cultures of anthrax were obtained in nature by Morris from Tahanus attains Fabricius caught feeding on a- carcass. This species will feed on a carcass thirty minutes or more after death. He likewise determined the spores in the feces of the Lyperosia up to six hours after feeding, of the Tabanus one to twelve hours after feeding, and of mosquitoes 48 to 72 hours after feeding. The above cited evidence should be sufficient to emphasize the absolute necessity of isolating and protecting from bloodsucking insects, animals sick with anthrax. Valuable animals should likewise be kept in screened buildings during outbreaks of the disease. Thallophyta: Fungi: Schizomycetes: Coccaceae Staphylococcus pyogenes albns and aureus Rosenbach, the causative organisms of various types of SEPTICAEMIA, were obtained by Joly (1898) from a Tabanus on a heifer near a municipal vaccine station. DISEASES TRANSMITTED BY BLOODSUCKING FLIES 211 Streptococcus sp., causative organism of SEPTICAEMIA, was re- corded from Stomoxys calcitrans Linnaeus bv Schuberg and Boing (1914). DISEASES OF UNKNOWN OR UNCERTAIN ORIGIN PAPPATACI FEVER, also known as Three-day and Phlebotomus fever, a disease of the Mediterranean regions, which has caused consid- erable disability to the troops, especially in Egypt and Greece, is trans- mitted by the bite of the sand fly, Phlehotomus papatasii Scopoli, and possibly other species in the genus. This disease is considered very closely related to dengue, if not identical, by ]Megaw (1919) and others. Its transmission has been clearly demonstrated by Doer, Franz and Taussig (1909). The blood is infective for only about 2-i hours. During this period the flies become infected by feeding on the patient. After ingesting the virus, there is an incubation period of seven to ten days before the insects become infective, and beyond this after an indeterminate period the}' may again become non-infective. Following the bite of an infected fly, there is an incubation period in man of from 31 l' to 7 days, during which time the patient is non-infective. The virus is filterable. Lizards and reptiles are the wild reservoirs of the disease. VERRUGA PERUVIANA, or Carrion's disease, a Peruvian disease, thought to be caused by Bartonella haciUiformis Strong, Tyzzer, Brues, and Sellards is claimed by Townsend (1916) to be carried by Phlebotomus verrucarum Townsend, and he advances evidence to support his claim. EQUINE INFECTIOUS ANEMIA, or swamp fever of horses, a disease caused by a filterable virus in Japan, was thought to be carried by Chrysops japonicus Wiedemann, Chrysozona pluviatilis Linnaeus (Haemofopota tristis Bigot), Tabanus chrysurus Loew, T. trigonus Coquillett, T. trigeminus Coquillett, and Atylotus rufidens Bigot, ac- cording to the Horse Administration Bureau (1914) ; and in America was claimed by Scott (1915) to be carried by Stomoxys calcitrans Linnaeus. Howard (1917) conducted an experiment with Stomoxys cal- citrans which indicated the probability that this fly transmitted the disease. HOG CHOLERA, a disease caused by a filterable virus, has recently been transmitted by inoculating animals with infected Stomoxys calci- trans (Dorset, ct al., 1919). GLANDERS is associated by Fuller (1913) with Stomoxys cal- citrans outbreaks. POLIOMYELITIS, or infantile paralysis, a disease of unknown origin, has been suspected by various authors of being transmitted by biting insects, especially Stomoxys calcitrans and Tabanids. Rosenau 212 SANITARY ENTOMOLOGY and Brues (1912) conducted experiments with this fly and reported suc- cessful inoculations of six monkeys by bites of the flies. Anderson and Frost (1912) repeated these experiments and as a result three monkeys exposed daily to the bites of several hundred Stomoxys, which at the same time were allowed daily to bite two intracerebrally inoculated mon- keys, developed quite typical symptoms of poliomyelitis eiglit, seven, and nine days, respectively, from the date of their first exposure. Autopsy of all proved the presence of typical poliomyelitis lesions. On the other hand these same authors in further experiments (1913) and Sawyer and Herms (1913) record negative results with this fly. Fuller (1913) re- ports that it has been shown that epidemics of infantile paralysis usually occur with an abundance of the stable fly. PELLAGRA, a disease of unknown origin, introduced from Europe to America, was for a long time thought to be caused by eating spoiled corn. At present sentiment seems to favor considering that it is caused by lack of vitamines. However, it is important that we discuss in this lecture rather briefly the theories propounded regarding bloodsucking flies as possible transmitters of the disease. Sambon (1910) brought forward the theory that the disease is car- ried by the bufl'alo gnats Simulium spp. Jennings and King (1913b) and Jennings (1914) are inclined to believe that the incidence of this genus and of pellagra aff'ords sufficient evidence to exclude Simulium from the consideration. On the other hand Jennings and King in their three papers point out very strongly the possibility of Stomoxys calcitrans being concerned in the transmission of the disease. RICKETTSIA MELOPHAGI Noller, a body similar to those found in typhus, trench fever, etc., is found in the bodies of Melophagus ovinus, the sheep tick, but is not known to be associated with any disease. ANIMAL. ORGANISMS TRANSMITTED BY BLOODSUCKING FLIES Protozoa Mastigophora: Binucleata: Haemoproteidae Haemoproteus columhae Celli and San Felice, the cause of PIGEON MALARIA or haemoproteasis of Columha livia, is transmitted by the pigeon flies Lynchia maura Bigot in Algeria and India, and L. brimea Olivier in Brazil. Mrs. Adie (1915) worked out the complete life cycle in the fly, and Acton and Knowles (191'1) in the pigeon. Mrs. Adie succeeded in transmitting the disease to uninfected pigeons by the bites of Lynchia flies. The flies used were dissected and found to contain DISEASES TRANSMITTED BY BLOODSUCKING FLIES 213 zygotes and sporozoites. Parasites were found in the blood of the pigeons 28 days after the flies were first put on them. In the pigeon the asexual cycle is passed. The sporozoites are inocu- lated by the bite of the fly. They enter the red blood corpuscles in tlie lung capillaries where they develop into trophozoites and schizonts and divide into merozoites, which may continue the asexual cycle by entering other corpuscles and becoming trophozoites. On the other hand they may remain in peripheral circulation and develop into the sexual forms, the macro- and microgametocytes. These forms may persist in the pigeon's blood over winter. They are ultimatel}^ taken up from the MOCULATION 0* PiCEON BY Sire OF FLV CYCLE OF Schizogony in Columba Livia [PlOtONJ. CYCLE or Sporogony in Lynchia Maura. (Fly). LIFE CYCLE OF HAEMOPROTEUS COLUMBAE The Cause Of Pigeon Malaria. Fig. 41. (Pierce.) pigeon's blood by the fly and pass from its proboscis into the gut. They develop into gametes which conjugate to form zygotes in the lower por^ tion of the mid-gut. These become ookinetes and develop into oocysts in the gut wall. The oocysts divide into a multitude of sporozoites which find their way through the body cavity into the salivary glands and are ready for inoculation. The life cycle is graphically shown in the chart (fig. 41) which should be compared with that of Plasmodium (fig. 47) in the lecture on mosquito-borne diseases. Haemoproteus mansoni Sambon, the cause of HAEMOPROTEASIS OF THE RED GROUSE, is transmitted by the grouse fly, Ornithomyia lagopodis Sharp in which Sambon found ookinetes in the stomach. 214 SANITARY ENTOMOLOGY Certain species of Haomoproteus are mentioned in another lecture as transmitted by mosquitoes (see Chapter XVII). Mastigophora: Binucleata: Leucocytozoidae Leucocytozoon lovati Sambon and Seligman, the cause of LEU- COCYTOZOASIS OF THE RED GROUSE, Lagopus scoticus, is sup- posed by Fantham to be likewise transmitted by the grouse fly, Orni- thomyia lagopodis Sharp, in which he found vcrmicules. Mastigophora: Binucleata: Trypanosomidae As has been mentioned before, Chalmers' new classification of Trypan- osome genera is used in this volume, although criticized by Mesnil. The value of this classification can be seen in the various lectures in that it groups together species with similar host relationships. The two genera involved definitely in biting fly transmission are Castellanella and Dut- tonella. In the former the final stage in the insect takes place in the salivary glands, and'in the latter, elsewhere in the anterior portions of the insects. Those species which can not be definitely assigned to a genus are left in Trypanosoma (sens. lat.). Castellanella armamense (Laveran), cause of an EQUINE TRY- PANOSOMIASIS in Annam, is believed to be carried by Tabanidae and Hippoboscidae according to Castellani and Chalmers. CastellaneUa brucei (Plimraer and Bradford) Chalmers, cause of NAGANA, an African disease affecting many wild and domestic animals, is transmitted normally by bites of the tsetse flies, Glossina morsitans Westwood, G. hrevipalpis Newstead, G. pallidipes Austen, G. tacJiinoides Westwood, and G. fusca Walker, and may also be transmitted by the horse flies Atylotns nemoralis Meigen, and a Tabanus, and by the stable flies Stomoxys calcitrans Linnaeus, and S. glaucn. The organism must undergo part of its development in the alimentary canal of the fly. When fully developed it is found in tlie proboscis and is then capable of being inoculated into, animals by the bite of the fly. Trypanosoma sp., cause of AINO, an African disease of cattle probably identical with C. brucei, is suspected by Brumpt to be carried by Glossina longipennis Corti. Castellanella dimorplion (Laveran and Mesnil) Clialmers, cause of an African ANIMAL TRYPANOSOMIASIS, is carried by the tsetse flies, Glossina palpalis Robineau-Desvoidy, G. tachinoidcs Westwood, G. mor- sitans Westwood, and G. longipalpis Wiiedemann, and possibly by Lyperosia. The trypanosomes upon being taken up by the fly become established in the hind intestine and gradually extend forward until tliey reach the proboscis, when they become fixed and assume the leptomonad or crithidial form. DISEASES TRANSMITTED BY BLOODSUCKING FLIES 215 Castellanella eqmperdum (Doflein) Chalmers, cause of DOURINE of horses, has been experimentally transmitted by interrupted feedings of the stable fly, Stomoxys calcifrans Linnaeus and Atylotus tomentosiis Alacquart by Sergent and Sergent (1906). Castellanella evansi (Steel) Chalmers, cause of SLTRRA of cattle and horses, has been experimentally transmitted by bites of Stomoxys calci- trans Linnaeus, S. geniculatus Bigot and S. nigra Macquart. Either experimental evidence or strong suspicion points to transmission by the horse flies, Tabanus tropicus Linnaeus, T. striafus Fabricius, T. lineola Fabricius, T. atratus P'abricius, T. fumifer Walker, T. partitus Walker, HosrH (M/sn) Ho9TE(Tse:TS!:Ky) H0!rl(TsE,5tF..) Host I (A.T..OP.) W.LO Reservoir LIFE CYCLE OF TRYPANOSOMA GAMBIENSE. The Cause OfGambian Sleeping Sickness OpMan Host I TR.sELA-HuisPE.ei (^^^pl). H0SrI.EGu.SS,~A P.URA^IS (tsetse FLv). HostH. HoMOSAPiENj (Man). Fig. 43. (Pierce.) T. vagus Walker, T. mvnimus Van der Wulp, and other species of Tabanus and Haematopota. Certain writers have also suspected Lyperosia minuta Bezzi, Philaematomyia crassirostris Stein and Lyperosia exigua Meigen {Haematobia). The parasite has also been found in the stomach of Stomoxys geniculatus. Castellanella evansi mborii (Laveran), cause of INIBORI, a camel trypanosomiasis of Africa, is believed to be carried by Tabanus taeniatus Macquart and T. biguttatus Wiedemann. Castellanella gambiense (Dutton) Chalmers {nigeriense Macfie), cause of GAMBIAN AND NIGERIAN SLEEPING SICKNESS of man, has wild animals for its reservoir, and is principally transmitted by Glos- sina palpalis Robineau-Desvoidy and its variety fuscipes. Experimental 216 SANITARY ENTOMOLOGY evidence indicates that it can be carried by Glossina morsitans West- wood, G. fusca Walker, G. longjpennis Corti, G. pallidipes Austen, G. brevipalpis Newstead, G. tachin'oidcs Westwood, as well as Stornoxys calcitrans Linnaeus, and the mosquitoes mentioned in another lecture. After the trypanosomes are ingested in the blood of the fly, multiplication begins, usually in the midgut (fig. 42). After the tenth or twelfth day, many long, slender trypanosomes are found which gradually move for- ward into the provcntriculus. Such long, slender forms represent the limit of development in the lumen of the main gut. The provcntriculus type, developed about the eighth to the eighteenth or twentieth day, is not infective ; it may occur in the crop, but is not to be found permanently there. Between the tenth and fifteenth days multinucleate forms of trypanosomes are found, and may be styled multiple forms. Some of these latter may be degenerative. Long slender forms from the provcn- triculus pass forward into the hypopharynx. They then pass back along the salivary ducts, about sixteen to thirty days after the fly's feed. In the salivary glands they become shorter and broader, attach themselves to the surrounding structures and assume the crithidial facies. They remain attached to the wall and multiply. These crithidial stages diff'erentiate into the short, broad trypanosome forms, capable of swim- ming freely. These forms only are infective. After inoculation into the vertebrate these forms multiply by longi- tudinal division. Repeated division occurs until the blood swarms with parasites. They then disappear from the blood and become latent non- flagellate bodies in the intestinal organs. These latent bodies again become flagellate and enter the general circulation, and may be taken up by a bloodsucking fly. The above life cycle was worked out by Miss Robertson as well as other workers and briefed by Fantham, Stephens and Theobald. Castellanella pecaudi (Laveran), cause of BALERI, a fatal equine trypanosomiasis of Africa, is usually spread b}^ Glossina longipalpis Wiedemann and G. morsitans Westwood, but G. tachimoides Westwood and exceptionally G. palpalis Robineau-Desvoidy may be infected. Stomoxys calcitrans Linnaeus and S. nigra Macquart are recorded as possible carriers. The incubation period in G. longipalpis is 23 days. The trypanosomes multiply in the fly intestine up to 48 hours after ingestion in a modified form, called by Roubaud the "intestinal try- panosome form." Under favorable conditions these multiply very rapidly and in seven to nine days invade the whole of the intestine as far as the pharynx. These flies are not infective until the parasites have invaded the proboscis and passed through the crithidial and leptomonad phases. These proboscis forms multiply and some reach the hypopharynx, where DISEASES TRANSMITTED BY BLOODSUCKING FLIES 217 they assume the "salivary trypanosome form" and are then capable of infecting any susceptible animal (Hindle). Castellanella rhodesiense (Stephens and Fantham) Chalmers, cause of RHODESIAN SLEEPING SICKNESS of man, is carried by Glossina morsitans Westwood, G. palpalis Robineau-Desvoidy, and G. bretnpalpis Newstead. The insect becomes infective after an incubation period of about 14 days and is infective throughout tlie remainder of its life. The life cycle is not completely worked out, but it is known that the try- panosomes first become established in the intestines and later invade the salivary glands (Hindle). Castellanella soudanense (Laveran) Chalmers, cause of TAHAGA of dromedaries in Sudan, EL DEDAB of dromedaries in Algeria, and ZOUSFANA of horses in Sud Oranais, has been experimentally trans- mitted by Stomoxys calcitrant Linnaeus, S. nigra Macquart, Atylotus nemoralis Meigen, and A. tomentosus Macquart. .Duttonella caprae (Kleine) Chalmers, cause of an African goat Try- panosomiasis, is transmitted by Glossina hrevipalpis Newstead and G. morsitans Westwood. Duttonella cazalbojii (Laveran) Chalmers, cause of SOUMA, an African animal trypanosomiasis, is principally carried by the tsetse flies Glossina palpalis Robineau-Desvoidy, G. longipalpis Wiedemann, G. mor- sitans Westwood, and G. tachinoides Westwood, but may also be trans- mitted by Stomoxys calcitrans Linnaeus, Tahanus higuttatus Wiede- mann, and T. taeniatus Macquart, and possibly Stomoxys nigra Mac- quart. Development of the organism is restricted to the proboscis of the tsetse fly, the flagellates never multiplying in any other part of the alimentary canal. They may change in the proboscis into lep- tomonad or crithidial forms, attach \o the walls of the labrum and under- go rapid multiplication. Under the influence of the salivary secretion some of these fixed flagellates develop into small, actively motile try- panosomes closely resembling the blood forms. This becomes infective from six to ten or more days after ingestion of the parasites. Duttonella cazalboui pigritia (Van Saceghem), cause of ZAMBIAN SOUMA of cattle, is carried by Haematopota perturbans according to Van Saceghem who found the organism in the intestinal tract of flies taken on infected animals. Duttonella congolense (Broden) Chalmers, cause of GAMBIAN HORSE SICKNESS, is carried by Glossina morsitans and possibly by G. palpalis and species of Glossina, Tabanus and Stomoxys. The various forms of the parasite have been demonstrated in the alimentary canal of G. morsitans 23 days after ingestion. Duttonella nanum (Laveran) Chalmers, cause of a fatal BOVINE TRYPANOSO]MIASIS of Africa, is carried by Glossina palpalis, and 218 SANITARY ENTOMOLOGY possibly G. morsitan^. The development in the gut of palpalis is similar to that described above for T. gambiense. Multiplication begins in the hind intestine and by the tenth day numerous parasites are found in the hind and middle intestine. The slender forms begin to be produced from the tenth to the fourteenth day onward, and the proventriculus is usually invaded about the twentieth day. About the 25th day they invade the proboscis, where they may be found attached to the labrum, often lying in clusters. They then pass through the crithidial phase, many of them being extremely long and slender. Subsequently trypanosome forms are produced which may be found free, sometimes in the hypopharynx and at other times in the labrum. The salivary glands never become infected. (Taken from Hindle who summarizes the work of Duke and others.) Duttonella pecorum (Bruce, Hamerton, Bateman and Mackie), cause of a WILD ANIMAL TRYPANOSOMIASIS, is carried by Glossina morsitans, G. tachinoides, G. palpalis, and G. brevipalpis, in the alimen- tary canal of which it undergoes its cyclical development, Duttonella simiae (Bruce, Harvey, Hamerton, Davey and Lady Bruce), cause of SIMIAN TRYPANOSOMIASIS, is carried by Glossina morsitans and G. brevipalpis . Duttonella uniforine (Bruce, Hamerton and Mackie), a fatal TRY- PANOSOMIASIS of cattle, with wild animal reservoirs, is naturally carried by Glossina palpalis, which becomes infective in from 27 to 37 days. The infection of the fly is always limited to the proboscis. Duttonella vivax (Ziemann) Chalmers, cause of a bovine and ovine TRYPANOSOMIASIS, is carried by Glossina tachinoides, and probably by G. palpalis and G. inorsitans. Stomoxys and Lyperosia are suspected carriers. The incubation period of the fly is from five to eight days. Trypanosoma franki Frosch, cause of a TRYPANOSOMIASIS OF WILD GAINIE in Europe, is believed to be transmitted by Hippoboscidae and Tabanidae. Trypanosoma gallinarum, cause of FOWL TRYPANOSOMIASIS of the domestic fowl, is carried by Glossina palpalis, according to Duke (1912). Trypanosoma grayi Novy, cause of CROCODILE TRYPANOSOMI- ASIS in Africa, is carried by Glossina palpalis and G. brevipalpis. Trypanosoma tlieileri Laveran, thought to cause GALL SICKNESS of cattle by some authors, was experimentally transmitted by Theiler in South Africa by bite of Hippobosca rufipes Von Olfers and H. maculata Leach. Trypanosoma tullochi Minchin is native to Glossina palpalis in Africa, and no vertebrate host is as yet known. DISEASES TRANSMITTED BY BLOODSUCKING FLIES 219 Mastigophora: Binucleata: Leptomonidae Crithidia melopliagia Flu is normally a parasite of the sheep tick fly, Melophagus ovinus Linnaeus, and has been experimentally transmitted to rats and mice. Flu (1908) describes in the fly an asexual and sexual reproduction. The latter is characterized by a process of reduction, followed by conjugation with the formation of an ookinete and the infec- tion of the eggs of the insect, which may cause a second generation of flies to carry the organism. Crithidia nycterihiae Chatton is found in the parasite fly, Cyclopodia sykesi Westwood. Crithidia pangoniae Rodhain, Vandenbranden, Bequaert and Pons occurs naturally in Tabanus hilaris Walker, T. striatus Fabricius, and a Tabanus sp. Crithidia tenuis Rodhain, Pons, Vandenbranden and Bequaert is native to Haematopota duttoni Newstead, and H. vandenhrandeni Rod- hain, Pons, Vandenbranden and Bequaert in Belgian Congo. Leishmania brasiliensis Vianna, cause of BOUBA or oral leishmaniasis of Brazil and Paraguay, is believed by Brumpt and Pedroso to be carried by bloodsucking flies, either Tabanidae or Culicidae. Leishmania tropica (Wright), cause of BISKRA SORE in Algeria, and BAGDAD SORE in Bagdad, is believed by Wenyon (1911) and Sergent and Sergent (1914) to be transmitted by Phlebotomus minutics africanus Newstead. Leishmania uta Escomel, cause of UTA, a dermal lesion peculiar to the western face of the Andes in Peru, is believed by Townsend to be carried by Forcipomyia utae Knab and F. townsendi Knab. Leptomonas minuta (Leger) occurs naturally in the intestine and Malpighian tubules of Tabanus tergestinus Egg. Leptomonas phlebotomi (Mackie) occurs in nature in Phlebotomus minutus Rondani in India. Leptomonas simuliae (Georgewitch) occurs in nature in Simulium columbaczense Schonberg in Europe. Leptomonas subulata (Leger) attacks Haematopota italica Meigen in Southern France. Mastigophora: Spirochaetacea: Spirochaetidae Spiroschaudmnia glossinae (Novy and Knapp) occurs in the stomach of Glossina. Telosporidia: Haemogregarmida: Haemogregarinidae Haemogregarina francae Dc Mello, a parasite of the dove, Columba livia, is suspected of being carried by Lynchia maura Bigot. 220 SANITARY ENTOMOLOGY Haemogregarina sp. passes its sporogony in Glossina palpalis but its vertebrate host is unknown. Metazoa Nemathelminthes: Nematoda: Filariidae Filaria (Loa) loa (Guiyot), cause of a human filariasis, was found by Ringenbach and Guyomarc'h in the Congo to pass part of its life cycle in Chrysops centurionis Austen, and by Leiper in West Africa in Chrysops dimidiata Van der Wulp, and C. silacea Austen. Leiper obtained a slight degree of infection but development was unequal and slow in Haematopota cordigera Bigot and Hippocentrum trimaculatum Newstead. He obtained only negative results with Stomoxys nigra Macquart, iS*. calci- trans Linnaeus, Glossina palpalis Robineau-Desvoidy, Tabanus par Walker, T. socialis Walker, T. fasciatus Fabricius, and T. secedens Walker. Thus it will be seen that many of the most dangerous diseases of animals and some of the most dreaded human diseases are carried by bloodsucking flies, and furthermore, that the transmission is principally biological, that is, the insect is a necessary intermediate host. In this case the parasite invariably passes its cycle of sporogony in the inver- tebrate and its cycle of schizogony in the vertebrate, if it passes through such a cycle. A number of organisms found only in the insects are recorded. It is quite possible that some of these will ultimately be linked up with pathological species. Any one studying disease transmission must know in advance what organisms he might encounter in the insects he is studying. BIBLIOGRAPHY Anderson, J. F., and Frost, W. H., 1912.— U. S. Treas. Dept., Public Health Report, vol. 27, No. 43, Reprint No. 99, 5 pp. Anderson, J. F., and Frost, W. H., 1913.— U. S. Treas. Dept., Public Health Report, vol. 28, p. 833. Brumpt, E., 1902. — Arch, de Parasit., vol. 5, p. 158. Castellani, A., and Chalmers, A. J., 1913. — Manual of Tropical INIedi- cine, 2nd edit. Doer, Franz, and Taussig, 1909. — Das Pappatacifieber. Franz Deuticke, Leipzig and Wien. Dorset, M., McBryde, C. M., Nile, W. B., and Rietz, I. H., 1919.— Amer. Journ. Vet. Med., vol. 14, No. 2, pp. 55-60. Duke, H. L., 1912.— Proc. Roy. Soo., vol. B 85, No. B 580, pp. 378-384. DISEASES TRANSMITTED BY BLOODSUCKING FLIES 221 Fantham, H. B., Stephens, J. W. W., and Theobald, F. V., 1916.— The Animal Parasites of Man. William Wood & Co. Flu, P. C, 1908.— Arch. f. Protistenk, vol. 12, pp. 147-153. Francis, Edward, 1919. — U. S. Treas. Dept., Public Health Reports, vol. 34, No. 37, pp. 2061, 2062. Fuller, C, 1913. — Fly Plagues. An unusual outbreak of Stomoxys cal- citrans following floods. Union of South Africa, Dept. Agr., circ. 32, 1913. Hindle, E., 1914. — Flies in Relation to Disease. Blood-Sucking Flies. Cambridge Univ. Press., 398 pp. Hintermayer, 1846. — Centralarchiv. f. d. gesamte Staatsarzneikunde, Band 3, pp. 437, 441. Horse Administration Bureau, 1914. — Tokyo. Reviewed in Bull. Inst. Pasteur, vol. 12, No. 14, p. 634. Howard, C. W., 1917.— Journ. Parasit., vol. 4, pp. 70-79. Jennings, A. H., 1914. — Journ. Parasit., vol. 1, pp. 10-21. Jennings, A. H., and King, W. V., 1913. — (1) Journ. Amer. Med. Assoc, vol. 65, pp. 271-274; (2) Amer. Journ. Med. Sci., vol. 146, pp. 411-440. Joly, P. R., 1898. — Importance du role des insectes dans la transmission des maladies infectieuses et parasitaires. — Du formol comme insecti- cide. Bordeaux. Imprimerie du Midi. 90 pp. Thesis. Leiper, R. T., 1914. — Rept. Advis. Comm. Tropical Research Fund for 1913, London, p. 86. Megaw, J. W. D., 1919.— Indian Med. Gaz., vol. 54, No. 7, pp. 241-247. Mitzmain, M. B., 1914. — U. S. Treas. Dept., Hygienic Laboratory, Bull. 94, 53 pp. Morris, Harvey, 1918. — Blood-Sucking Insects as transmitters of Anthrax or Charbon. La. Agr. Exp. Sta., Bull. 163, 15 pp. Nuttall, G. H. F., 1899. — On the Role of Insects, Arachnids and Myria- pods as carriers in the spread of bacterial and parasitic diseases of man and animals. A critical and historical study. Johns Hopkins Hospital Reports, vol. 8, Nos. 1, 2, pp. 1, 152. Ringenbach, J., and Guyomarc'h, 1914. — Bull. Soc. Path. Exot., vol. 7, pp. 619-626. Rosenau, M. J., and Brues, C. T., 1912.— Mo. Bull. State Bd. Health Massachusetts, vol. 7, No. 9, pp. 314-317. Sambon, L. W., 1910.— Journ. Trop. Med. and Hyg., vol. 13, No. 19. Sawyer, W. A., and Herms, W. B., 1913. — Journ. Amer. Med. Assoc, vol. 61, pp. 461-465. Schuberg, A., and Boing, W., 1914. — Arb. Kais. Gesundheitsamte, Band 47, Heft. 3, pp. 491-512. 222 SANITARY ENTOMOLOGY Schuberg and Khan, 1912. — Arb. Kais. Gesundheitsamte, Band 40, Heft 2, pp. 209-234. Scott, J. W., 1915.— Science, vol. 42, No. 1088, p. 659. Sergent, Ed., and Sergent, Et., 1900. — Ann. Inst. Pasteur, vol. 20, pp. 665-681. Sergent, Ed., and Sergent, Et., 1914. — Bull. Soc. Path. Exot., vol. 7, pp. 577-579. Townsend, C. H. T., 1916.— Journ. Parasit., vol. 2, pp. 67-73. Townsend, C. H. T., 1916.— Bull. Ent. Res., vol. 6, pt. 4, pp. 409-411. Wayson, N. E., 1915.— U. S. Public Health Service, Public Health Reports, vol. 29, No. 51, pp. 3390-3393. Reprint No. 242. Wenyon, C. M., 1911.— Kala Azar Bull., vol. 1, pp. 36-58. J CHAPTER XV Biological Notes on the Bloodsucking Flies^ W. Dwigh t Pierce Mr. Webb, in his lecture which follows (Chapter XVI), has given us a very comprehensive view of the life history and habits of the horse flies of the genus Tabanus. In another lecture we presented the data on transmission of diseases by the bloodsucking flies and by reference to this (see Chapter XIV) it will be seen that quite a number of genera be- longing to several families of flies are concerned in disease transmission. It will be the aim of this lecture to present some of the salient biological facts concerning these genera so as to prepare the sanitarian for controlling those species in his territory, which might cause disease. The insects we have especially to deal with in this lecture are the sand flies of the genus Phlebotomus, in the family Psychodidae ; the horse flies of the genera Tabanus, Atylotus, Haematopota, Chrysops, and Chrysozona, of the family Tabanidae ; the biting flies of the genera Stomoxys, Lyperosia, Haematobia, and Glossina, of the family Muscidae ; and the parasitic flies of the genera INIelophagus, Lynchia, Hippobosca, and Omithomyia, of the family Hippoboscidae. There are of course many other genera of bloodsucking flies which may contain potential disease carriers. Interesting discussions of these flies are to be found in the books by Hindle, and Patton and Cragg. FAMILY CHIRONOMIDAE Midges The little midges of this family are often mistaken for mosquitoes, to which they are somewhat related. Their young are the well-known blood worms in streams and stagnant pools. Of the five subfamilies only one, the Ceratopogoninae, contains bloodsucking forms. The eggs of Chironomidae are small and ovoid, or long and pointed at their extremi- ties, and are laid either in a gelatinous string of mucus or separately. The larva consists of thirteen segments, with head directed downwards, and mandibles well developed. On the ventral surface of the eleventh * This lecture was presented October 14, and issued October 23, 1918. 223 224 SANITARY ENTOMOLOGY segment and the extremity of the twelfth, there are delicate finger-like processes, usually four in number, which serve as tracheal gills. The pupa is free and either lives floating in water without any movement or rests on the bottom of the pool. It has a tuft of delicate white threads on the dorsum of the thorax, which serve as breathing tubes; or it may have a pair of respiratory trumpets. Tersesthes torrens Townsend, a mountain form in North America, is a voracious bloodsucker, attacking man and animals, usually on the head, ears, and eyes. Its life history is unknown. Mycterotypus hezzii and M. irritans of Southern Europe are vora- cious bloodsuckers, biting human beings, as well as animals, and causing inflammatory swellings. Ceratopogon is a large genus containing a number of bloodsucking gnats called "punkies," found in various parts of the world. Some of the Asiatic species attack bloodsucking mosquitoes and draw blood from them. It is therefore possible that these insects may play a role in disease transmission. They are very small, measuring less than 3 mm. in length. Only the females are bloodsuckers. They bury themselves often among the hairs of the host and are not recognized until they become replete with blood. They often cause great distress on account of their num- bers and the irritation produced by their bites. The different species choose different parts of the host for attack, as for example, some select the face, especially the margins of the ears and eyes, while others may attack the arms or legs. Forcipomyia utae Knab is thought by Townsend to cause the South American disease, uta. Forcipomyia is considered to be a subgenus of Ceratopogon. Larvas have been found in crab holes and below the algal crust on the sand along the seashore in South America. Culicoides is another large genus of midges very similar to Cera- topogon, and contains many bloodsuckers. Only the females bite. The larvae are found in water under various conditions. When searching for larvae where the adults are abundant, they may be found by gathering in a white tray some of the green vegetable matter found at the edges of streams. The flies can be bred by placing the pupje on moist filter paper in tubes closed with moist cotton. The genera Johannseniella and Haematomyidium also contain blood- sucking midges. FAMILY SIMULIIDAE Buffalo Gnats The buffalo gnats of the genus Simulium are sometimes also called sand flies and turkey flies. This is a large genus of voracious flies which often are so numerous as to cause great distress and even death to men BIOLOGICAL NOTES ON BLOODSUCKING FLIES 225 and animals, Sambon considered Simulium as the carrier of pellagra, but his theory has not been substantiated. Jobbins-Pomeroy has given quite a full treatment of the life history of several species of this genus, and Malloch has presented a classification of our American forms. The larvae breed usually in swift-flowing water. The eggs are small, rather triangular or ovoid objects, and somewhat yellowish in color after a few days. They are laid in masses on grass blades, or leaves, or on stones and other forms of debris at the surface of the water or under the surface. The egg stage varies in each species according to the temperature, but in Jobbins-Pomeroy's studies of five Fig. 43. Larva of a buffalo gnat, Simulmm. (Jobbins-Pomeroy.) species, the incubation period ranged from 7 to 13 days. A single female may lay from 500 to 1500 eggs according to published claims. The larvae are invariably aquatic, and are quite characteristically marked by the possession of two large appendages on the head in front of the antennae, which are provided with fans of long hairs. These fans serve to brush food particles into the mouth of the larva (fig. 43). The mesothorax is provided with a single retractile proleg armed at its apex by a circular row of short booklets or spines. This pseudopod with its sucker is used by the larva in attaching itself to objects. A simi- lar but larger sucker-like disk is situated on the caudal extremity of the larvtT. Respiration takes place through rectal gills located dorsally to the caudal sucker. These gills are retractile into the rectum, but are 226 SANITARY ENTOMOLOGY usually extended in running water. They function both as blood gills and tracheal gills. The structure of these gills affords characters of value for the identification of the species. The larvae attach themselves by the caudal suckers and float in the stream, catching their food by means of the fan-like processes on the head. When disturbed, or if the stream diminishes, the larva* let them- selves float down the stream attached by a silken thread to a permanent object, by which they can regain their former position. When about to pupate the larva spins over itself a pocket-shaped pupal case. The pupae are provided with respiratory organs on each side of the thorax. These are composed of long chitinous tubes with a single main stalk and four or more divisions. Good specific characters for identification are found in the structure of these respiratory organs (plate XV). The development period of Simulium in South Carolina is about 7 days for the egg, 17 days for the larvae, and 4 days for the pupae. The number of generations depends upon the species and the season and may range from one to six or more generations. FAMILY PSYCHODIDAE Pappataci Flies The owl midges are small moth-like flies. Only the genus Phlebotomus contains bloodsucking flies, Which are often called sand flies. T!h,d pappataci fly, Phlebotomus papatasii Scopoli, cause of pappataci fever; P. minutus Rondani, a possible carrier of Bagdad sore, and P. ver- rucarum Townsend, supposed carrier of verruga, are the only species definitely charged with carriage of disease. Only the females suck blood. They deposit their eggs in damp, dark places, in clusters or singly, to the number of from 30 to 80. The eggs are covered with a thin coating of a sticky substance which causes them to adhere to any surface. They are very elongate, dark bro\vn, with longitudinal, black, wavy lines. The incubation period is from six to nine days. The larvae live in damp earth. They are very peculiar, having large, well marked heads with big jaws, which have four distinct teeth. The body is covered with toothed spines and the posterior end bears two pairs of very black caudal bristles, one pair of which are as long as the body. The larva feeds on semi-decaying vegetable matter. The pupa is remarkable for the large ridges and excrescences on its thorax. The larval skin usually remains adhering to the caudal extremity. These flies breed in crevices of stone walls and fissures between rocks in caves, in dirty, damp cellars, and on the damp walls of latrines and cesspools, and wherever there is damp ground in dark places. Lizards fre- BIOLOGICAL NOTES ON BLOODSUCKING FLIES 227 Plate XV. — Pupae of Simidium. Fig. 1. — Respiratory filaments of pupa of SimuUum vittatnm. Fig. 2. — Pupa of Simnlium vemtstum, in pupal case. Fig. 3. — Pupa of SimuUum hracteatum : A, side view of filaments. Fig. 4. — Pupa of SimuUum jen- ningsi. Fig. 5. — Pupa of SimuUum pictipes, in pupal case. All greatly enlarged. (After Jobbins-Pomeroy.) From U. S. Dept. Agr. Bull. 329, Plate V. 228 SANITARY ENTOINIOLOGY quently serve as blood hosts and are considered the reservoirs of the fevers carried, especially pappataci fever. FAMILY CULICIDAE The mosquitoes which in an orderly arrangement would be treated here have been considered in other lectures (Chapters XVII to XIX)., The families so far discussed belong to the Nematocera; the next family belongs in the Brachycera. FAMILY TABANIDAE Horse Flies The family Tabanidae contains the horse flies, gad flies, deer flies, many genera and species of bloodsuckers. The males throughout the family are flower feeders or feed on vegetable juices, and so likewise are the females in many genera. The eggs of Tabanidae are commonly laid in large, shapely masses on the leaves and stems of plants growing in marshy ground, or overhanging water. In some species they are deposited on stones or rocks above the water of streams, and are very difficult to discover. Mr. Webb has discussed for us the habits of Tabanus (Chapter XVI). We have seen also that species of Tabanus can carry the animal diseases anthrax, nagana, souma, surra, and mbori. The genus Atjdotus can carry nagana and dourine ; Haematopota, surra and equine infectious anemia ; Chrysops and Chrysozona are probable carriers of equine infec- tious anemia. Various other genera are bad bloodsuckers, especially Pangonia. Tabanid larvae grow very slowly, feeding at first on small crustaceans which are abundant in water and moist earth. The larger larvae of many species feed almost exclusively on earth worms, whose body juices they suck out. Although the larval stage may require months for development, the pupal stage will usually be short. FAMILY MUSCIDAE The flies of the family IMuscidae are mostly not bloodsucking flies. Principal among these genera which have the mouth shaped for sucking blood are the genera Glossina, Stomoxys, Lyperosia, Philaematomyia and Haematobia. Bloodsucking Fly Larvce The genus Auchmeromyia of Africa is very peculiar in that both larvae and adults are bloodsuckers. The adult flies are sensitive to light and are 4 BIOLOGICAL NOTES ON BLOODSUCKING FLIES 229 usually found in the darkest parts of the native huts. The females have two periods of oviposition about one month apart, and may deposit a total of as many as 83 eggs. They oviposit on the ground in the huts, preferably Avhere urine has been voided. The lar\^ag are exclusively blood feeders. They are able to resist starvation for long periods. If fed regu- larly they may mature in about 15 days. They remain in hiding during the day and suck the blood of sleepers at night. Pupation occurs in the puparium or last larval skin. The fly is probably spread from village to village in the egg or larval stage in the dirty mats which the natives carry about with them. Travelers in Africa should always avoid sleeping in native huts or on the ground in the vicinity of corrals or native villages, because of these larA'ae and also many other venomous and disease-bearing pests. The African genus Choeromyia also has bloodsucking larvae, the. attack of which is not to be confused with the myiasis caused by the larvae of related genera, because these larvae are free living and do not remain attached to the host. Biting Species of Musca The genus Musca apparently is a transitional genus as it contains both non-bloodsucking and bloodsucking flies. Musca pattoni Austen, M. gibsoni Patton and Cragg, M. convexifrons Thomson, M. nigrithorax Stein, M. hezzii Patton and Cragg and M. corvina Fabricius, all of India except the last, which is European, are bloodsucking. But these flies are incapable of puncturing the skin of an animal. They feed on the blood and serum exuding from the bites of other bloodsucking flies. These flies breed in cow dung. M. pattoni always deposits in dung where it is collected in heaps, while gibsoni and convexifrons deposit in isolated patches of cow dung. True Biting Flies The true biting Muscids belong to the subfamilies Stomoxydinae, Glossininae and Philaematomyinae. Philaematomyia is a genus closely resembling Musca in appearance. It contains three Asiatic species, of which the best known is P. insignis Austen, which only attacks cattle. It breeds in cow dung where it is collected in heaps. Both sexes feed on blood although they have also been seen feeding on cow dung. This habit would surely make it possible for the fly to mechanically carry infectious diseases from dung to blood. It breeds quite rapidly. 230 SANITARY ENTOMOLOGY Stable Flies Stomoxys is a genus found principally in Asia and Africa, although S. calcitrans Linnaeus, the well-known biting stable fly, is almost world- wide in its distribution (figs. ^^-^Q, plate XVI). Tliis species is capable of carrying rodent plague, anthrax, septicaemia, nagana, souma, dourine, surra, baleri, and Gambian sleeping sickness, and has been connected by Scott with the transmission of equine infectious anemia and seriously suspected as a possible carrier of poliomyelitis and pellagra. A very complete bulletin by Bishopp is available for free distribution, describing the life history and control of the stable fly, so that it is not Fig. 44 (left). — Eggs of the stable fly (Stomoxys calcitrans) attached to a straw. Greatly enlarged. (After Bishopp.) Fig. 45 (center). — The stable fly: Larva or maggot. Greatly enlarged. (After Bishopp.) Fig. 46 (right). — The stable fly: Adult female, side view, engorged with blood. Greatly enlarged. (After Bishopp.) From U. S. Dept. Agr., Farmers' Bull. 540, figs. 1, 2, 5. necessary to give a full discussion in this lecture. It generally breeds in moist straw and hay. Stacked straw which has been wet and partly rotted and hence is no longer available for stock food is a very favorable place for the fly to breed. Such straw should be dried as soon as possible by scattering, and then either be burned or plowed under. The stable fly does not often develop in manure, but where it does it may be con- trolled by measures taken against the house fly. This species is very annoying to mules, horses, and cattle and often to man. Horses and mules often become frantic in their eff'orts to escape the flies. As much care should be taken to prevent the breeding of the stable fly as the house fly. They are carriers of entirely diff'erent series of diseases and both are dangerous. Especial care must be observed to BIOLOGICAL NOTES ON BLOODSUCKING FLIES 231 nH ^ ' Plate XVT. — The stable fly, Stomoxys calcitrans. Fig. 1 (upper). — Eggs in straw. Fig. 2 (lower right). — Pupae in straw. Fig. 3 (lower left). — Adults on leg of cow. (Bishoi)]).) 232 SANITARY ENTOMOLOGY prevent breeding in straw which falls out of the stalls and windows of the stables. Where the stables adjoin a road, considerable straw may fall out of the windows and remain outside the building in a place where the horses do not come, and no one may think of removing this straw with the daily removal of manure. Here is an excellent place for Stomoxys to breed. Wherever marine weeds and debris are washed ashore and form considerable masses, Stomoxys is likely to breed. In plate XVII is shown the proper method of stacking straw to prevent fly breeding. "fcaa^Siii pjf/i^v-i^ir .■^ESissss^.-.-i ."^■i«.:-:"«ts*^ Plate X\'II. — Straw stack sliowing proper metliod of building strawstack. (Bishopp.) Horn Flies Haematohia sanguisugens is an Indian bloodsucker, which attacks cattle and horses. The principal species of horn flies belong to the genus Lyperosia,^ of which L. irritans Linnaeus (plate XVIII) and L. exigua Meijere are the two commonest bloodsuckers. The latter is oriental. The horn fly was treated very fully by Marlatt in a circular now out of print. This species is so called because of the habit of the adults of clustering on the base of a cow's horn. The flies also cluster on other parts of the animal and cause great annoyance. Even when not feeding the flies rest on the cattle. The eggs are laid singly on the surface of wet dung. The moment the dung is dropped a swarm of flies dart from the animal to the dung and remain there a few seconds, during which time - Dr. J. M. Aldrich does not recognize Lyperosia, but places our American species in Haematohia. — W. D. Pierce. BIOLOGICAL NOTES ON BLOODSUCKING FLIES 233 Plate XVIII.— The horn fly, Lifperosia vrritans. Fig. 1 (upper).— Flies on cow. Fig. 2 (lower).— Cow pasture showing droppings improperly left to breed flies.. (Bishopp.) 234 SANITARY ENTOMOLOGY many eggs are deposited. The flies immediately return to the cow. The larvae migrate from the dung when about to pupate and the puparia are usually found at some distance away or under the sides of the patch of dung. The horn fly in America requires about 17 days from egg to adult. Protection of the animal from the horn fly by the use of repellents is suggested. In this connection Graybill's bulletin on repellents should be consulted. Dipping vats and the cattle dip of the Bureau of Animal Industry (see Chapter XXXI, p. 442), now used in the control of the Texas fever tick, aid materially in reducing horn fly numbers. Two practical methods are available for attacking the larvae and pups'. One is to throw lime on the dung, but the better method is to spread out the dung so as to favor its rapid drying or to allow a number of pigs to run with the cattle. In their eff^orts to obtain undigested food particles the pigs will eff'ectively destroy the dung as breeding places for the fly. Tsetse Flies The tsetse flies of the genus Glossina are among the most dreaded in- sects of Africa. Thej'^ are the carriers of three or more types of sleeping sickness, of aino, nagana, souma, horse sickness, balcri, and other trypanosomiases of many domestic and wild animals. There are quite a number of species, and probably all are important, but G. morsitans Wcstwood and G. palpalis Robineau-Desvoidy, are the best known. Excel- lent discussions of each of the important species and tables for differen- tiation are given in the textbooks of Hindle, and Patton and Cragg. The reproduction in this genus is very remarkable, resembling that of the Pupipara and is probably the result of their exclusively blood- sucking mode of life. The female lays a single larva at a time, which is retained and nourished in the oviduct until it is full grown. After the larva is born it at once burrows into the ground and pupates. The lai-va is generally of a yellowish white color and bears at its posterior extrem- ity a pair of large dark-colored protuberances between which is a depres- sion into which open the spiracles of the eighth segment. It pupates within the puparium or last larval skin. The puparium is broadly ovoid in shape and by its caudal appendages aff^ords a means of distinguishing the species. The habitats of the various species should be rather thoroughh'' studied by any one expecting sei'vice in the African tropics. In general the flies are found in moist forest regions, especially along river courses, but the temperature, moisture, and shade requirements seem to vary for the different species. BIOLOGICAL NOTES ON BLOODSUCKING FLIES 235 PUPIPARA The suborder Pupipara is composed of several families of the queerest flies in the order. The insects of the families Nycteribiidac, Streblidae and Hippoboscidae are all ectoparasites on warm blood vertebrates. All of the Streblidae and Nycteribiidae of which the life history is known, are parasitic on bats and some of them are quite probably the carriers of bat diseases. In the family Hippoboscidae we find the genera Lynchia, Hippobosca and Omithomyia, mentioned as carriers of disease, and also Melophagus to which belongs M. ovimis Linnaeus, the sheep tick. The flies of the genus Lynchia which carry pigeon malaria, live almost exclusively on pigeons. They deposit larva? in the pigeon houses ; these larA^ae become puparia in an hour. Hippobosca is composed principally of species parasitic on mammals, one of Avhich is thought to carry the gall sickness of horses in South Africa. The females deposit larva? which are incapable of movement. They slowly darken until the puparium resembles a seed. Lipoptena cervi is parasitic on deer. Melophagus ovinus, which is wingless, lives on sheep, sometimes proving to be an important pest. This insect may be eradicated by giving two thorough dippings at 24<-day intervals in lime-sulphur-arsenic solution or in stand- ard coal tar-creosote or crcsol dips, or nicotin solution (Imes). Outside of the stable fly and sheep tick, control measures for biting flies are not well worked out. Of course the primary essentials are protection of the animals from the bites of the flies and prevention of breeding. REFEREXCES Bishopp, F. C, 1913.— The Stable Fly. U. S. Dept. Agric, Farmers' Bull, 540. Available for free distribution. Graybill, H. W., 1914. — Repellents for Protecting Animals from the Attacks of Flies. U. S. Dept. Agric, Bull. 131. Hindle, Edward, 1914. — Flies in Relation to Disease. Blood-Sucking Flies. Cambridge Univ. Press. Imes, Marion, 1917. — The Sheep Tick and Its Eradication by Dipping. U. S. Dept. Agric, Farmers' Bull. 798. Available for free dis- tribution. Jobbins-Pomeroy, A. W., 1916. — Notes on Five North American Buffalo Gnats of the Genus Simulium. LT. S. Dept. Agric, bull. 329. Malloch, J. R., 1914. — American Black Flies or Bufl'alo Gnats. L". S. Dept. Agric, Bur. Entom., Tech. Bull. 26. Marlatt, C. L., 1910. — The Horn Fly. U. S. Dept. Agric, Bur. Entom., Circ. 115. Patton, W. S., and Cragg, F. W., 1913.— A Textbook of Medical Ento- mology. CHAPTER XVI Biolog}^ and Habits of Horse Flies ^ J. L. Webb In various parts of the United States and in many foreign countries horses, cattle, and similar animals suffer severely from the bloodsucking habit of the so-called horse flies of the genus Tabanus (plate XIX). Plate XIX. — Tabanidae attacking cattle: Tabanus phaenops on cow's jaw, and T. punctifcr on top of shoulder. (Blshopp.) The life history and liabits of different species may vary greatly. Yet there are certain conditions common to all species. In general, the flies of this genus are to be found in or near swampy areas of the counti-y. *This lecture was read October T, 1918. 236 BIOLOGY AND HABITS OF HORSE FLIES 237 The larval stage of most species is passed in the ground, and a certain degree of moisture is necessary for proper growth and develop- ment. Most species require very wet, or saturated soil, others are able to develop in moderately moist earth. EGGS AND EGG XAYIXG The eggs are deposited by the female fly in clumps of several hundred each, on vegetation, rocks, or other objects overhanging suitable places for development of the larvae. When the eggs hatch, the young larvae drop to the soil or water beneath and disappear from sight. Here they remain for several months, sometimes for one or two years, when, after passing through a short pupal period, they emerge as adult ffies. In some cases the •egg mass as well as the place of oviposition is characteristic of the species, and renders identification eas}'^, once the observer sees one of which he knows the identity. In the Sierra Nevada Mountains of Eastern California where I havd been studying tabanids for the past two years, the egg masses of the two most important species are very easily distinguished. The egg mass of Tabanus piinctifer Osten Sacken is oblong, somewhat pyramidal in shape, and about the size of the end of a man's little finger (plate XX, fig. 1). It is usually deposited upon a bullrush or coarse grass stem, and from one to thi'ee feet above the surface of" the soil or water. When deposited, as is the case with all horse fly eggs, tlie mass is milk white. In a day or so, however, the color darkens to a mottled gray and white. Eggs of this species are found most abundantl}'^ along lake shores. The egg mass of Tabanus phaenops Osten Sacken is to be found on grass blades, three or four inches above the soil in swampy places in meadows. This mass is considerably smaller than that of Tabanus punctifer, is elongate, and usually contains but two layers of eggs, while the other species usually has about five layers. The egg mass of T. phaenops is black a day or two after oviposition. This mass is inconspicuous and extremely hard to locate in nature. In the Egyptian Sudan, Harold King found the eggs of Tabanus k'ingi Austen deposited in rounded masses on rocks rising from the edge of a stream, generally overhanging the water, and from 6 inches to 15 inches above the water level. He also found the masses of Tabanus ditaeniatus Macquart on grass growiiig in rain pools. The shape of the egg mass of this species was variable, — some being long and narrow, others short and broad. The same worker secured ovipositions of Tabanus par Walker in a cage, on the under sides of leaves of a water weed growing in a vessel of water. He also secured the egg masses of Tabanus taeniola Palisot