Flies

FLIES, the general name for insects of the order Diptera, group Brachycera, class Insecta, phylum Arthropoda; characterized by a massive body and short three-segmented antennae. The freely movable head bears a pair of, in most cases, very large compound eyes, in addition to which there are 2 to 3 simple eyes on the vertex. The mouthparts are piercing-sucking or licking-sucking. A complete set of their parts is present in horseflies; these organs are entirely reduced in botflies; in the majority of flies, they consist of a grooved lower lip (Fig. 1) ending in annular lobes, in which lies the tongue (hypopharynx) pierced by the salivary duct; the groove is covered from above by an elongated upper lip. The tarsi end in a pair of claws with 2 to 3 adhesive pads, thanks to which flies can crawl on glass (Fig. 2). The wings are membranous, transparent, and sometimes entirely reduced. Their venation varies (Fig. 3). The abdomen consists of 5 to 8 visible segments. The digestive tract in the head is equipped with a system of muscles working like a pump. A long tubular crop opens into the anterior part of the esophagus (Fig. 4). The stomach and intestines are thin and long. There are 4 to 5 Malpighian tubules. The salivary glands are long and tubular (Fig. 5); their common duct opens at the beginning of the salivary channel of the tongue. The tracheae expand in places into voluminous air sacs. The male reproductive apparatus (Fig. 6) consists of testes, vas deferens and ejaculatory ducts, a pair of accessory glands, and a copulatory apparatus. The female possesses a pair of ovaries, oviducts, a uterus, vagina, spermathecae, and accessory glands (Fig. 7). Some flies are viviparous. Larvae emerge from the egg while still within the mother's body and in some flies feed on the secretion of accessory glands or by means of special placental adaptations (Fig. 8). Flies reproduce with complete metamorphosis. The larvae lack a distinct, definite head and have mouthparts consisting of two chitinous hooked sclerites (Fig. 10); tracheal spiracles open either at the rear of the body on a special spiracular plate or along the sides of the abdominal rings; anterior stigmata also occur (Fig. 9). The shape and structure of the stigmal plates vary in different species of flies (Fig. 11). Fly larvae live in water, in the soil, in plants, in decomposing animal and plant remains, and in living organisms. During the final molt of the larvae of many flies, the skin is not shed, but forms a barrel-shaped case or false cocoon (puparium) (pupa coarctata) around the pupa (Figs. 12 and 13). Suborder Orthorrapha, straight-seamed. Upon hatching of the fly, the puparium opens anteriorly with a T-shaped slit. Family Stratiomyidae, soldier flies. Family Tabanidae, see Horseflies. Family Bombyliidae, bee flies; there are among them no bloodsuckers, but many larvae parasitize the larvae and pupae of various beneficial and harmful insects. Family Asilidae, robber flies; predatory flies (among them the largest of the Diptera) that attack other insects; they do not touch humans; Satanas, Laphria, etc. Suborder Cyclorrhapha, circular-seamed. Upon hatching of the fly, the anterior end of the puparium pops off in the form of a round lid. Family Phoridae, small flies with parasitic larvae; Phora incrassata infests larvae of the honeybee; Phora rufipes, living in decomposing substances, can enter the human gastrointestinal tract along with spoiled potatoes, mushrooms, etc. (see Myiasis). Family Syrphidae, hoverflies; mostly brightly colored, mimicking Hymenoptera; Eristalis tenax, the drone fly; its larva (called a rat-tailed maggot) with a long breathing siphon and impermeable body skin lives in very polluted waters, burrowing into silt; it is an "indicator organism." Family Tachinidae, tachinid flies, with larvae parasitizing the larvae of various insects, in particular harmful butterflies; important enemies of pests. Representatives of the genus Sarcophaga — S. carnaria (Fig. 14), the flesh fly; its larvae live in decomposing carcasses and spoiled meat; the genus Sarcophila-Wohlfahrtia is characterized by the parasitism of larvae in the living tissues of the host (see Wohlfahrt's fly). Flies of the genera Lucilia (L. caesar—"green bottle fly"; Fig. 15), Cynomyia (C. mortuorum, carcass fly) are scavengers according to their habitat. Genus Calliphora; C. erythrocephala, the common bluebottle fly (Fig. 16); C. vomitoria with larvae living in decomposing meat and carcasses; Cordylobia anthropophaga (West and Tropical Africa, Fig. 17); larvae live in the skin of humans, domestic and wild animals; Cochlyomyia macellaria (Lucilia hominivorax = Calliphora anthropophaga), from the USA to Argentina; larvae in ulcers and wounds of domestic animals, while the larvae of Chrysomyia dux (India, Australia) also occur in humans. Family Muscidae, true flies; bloodsucking and non-bloodsucking forms belong here. Flies lacking a piercing apparatus can also drink exuded blood. Among the non-piercing flies, the house fly is particularly important (see below). The piercing ones include the tsetse fly (see Glossina) and the stable fly (Stomoxys calcitrans). The stable fly is 5–6 mm long (Fig. 18 a, b, and c) and is closely associated in its existence with the horse. It is numerous in late summer and autumn; it painfully bites humans, horses, and cattle. It exhausts animals, reduces milk yield, meat gain, and mechanically transmits anthrax bacilli through its mouthparts during successive feeding on sick and healthy animals. It lays up to 100 eggs about 1 mm long in horse manure and heaps of rotting plant debris. Larvae hatch after a day or later. Mature larvae are 8–9 mm long. The larval stage lasts 2–4 weeks. The false cocoon is rusty-brown; the pupal stage is 12–17 days. The entire development of the stable fly at the latitude of Leningrad lasts 22–31 days, in the south—half as long. For control of the stable fly, see below. Lyperosia irritans, the southern or small cattle stable fly (Fig. 19), and Haematobia stimulans, the common (northern) cattle stable fly, are economically important parasites of cows. L. irritans lays eggs in the freshest cow dung. Muscina stabulans, the house stable fly, is found in rooms, on verandas, galleries, barns, stables, etc. It can penetrate dark rooms to lay eggs. Its larvae develop in feces, manure, and rotting plant substances. Its larvae destroy the larvae of the house fly and Hydrotoea dentipes. M. stabulans can contaminate food substances with bacteria, including pathogenic ones, which it spreads on its feet and proboscis.

Previously classified within the now abolished family Anthomyidae, Homolamyia (Fannia) canicularis can, like the house fly, contaminate foodstuffs with various infectious bacteria and contribute to the spread of certain infectious diseases. - Fam. Scatomyzidae, dung flies. - Fam. Ephydridae; the larvae of Ephydra riparia live in strong salt solutions and brine. - Fam. Drosophilidae, fruit flies - see Drosophila. - Fam. Piophilidae, Piophila casei, the cheese fly (Fig. 20); lays eggs on cheese and in barrels of salted fish; its larvae are known as cheese skippers, as well as "jumpers" because they readily jump by hooking their mouthparts onto the substrate on which they crawl for several tens of centimeters, damaging stocks of salted fish. They are easily swallowed with food by humans and frequently cause rather severe cases of intestinal myiasis (see). When larvae are frequently collected with bare hands, they cause skin irritation. Within the suborder Cyclorhapha, the group Pupipara is distinguished, the pupiparous flies; the larva develops within the maternal organism and pupulates shortly after birth, which explains the somewhat imprecise name of the suborder. Flies of this group are blood-sucking and parasitize mammals and birds, being closely associated with the host due to partial functional or complete reduction of the wings. - Fam. Hippoboscidae, louse flies; Hippobosca equina, parasitizes horses; Lipoptena cervi (Fig. 21) on deer; Melophagus ovinus (sheep ked) (Fig. 22) on sheep, is a vector of sheep trypanosomiasis (Trypanosoma melophagium). Parasitizing birds are Ornithomyia avicularia, Lynchia maura (Fig. 23), a vector of the pigeon hemoproteid (Haemoproteus columbae) in Southern Europe, North Africa, and India; in other places, vectors of the same parasite are other species - L. lividicolor, L. brunea in southern Africa, etc. - Fam. Nycteribiidae (wingless) and Streblidae (mostly winged) contain parasites of bats with a heavily modified external appearance. The utility of flies: 1) Parasitizing many agricultural or sanitary-hygienic slaughterhouse waste, spoiled meat, kitchen garbage, plant residues, as well as sputum, suppurating wounds, manure, etc. A single deposition yields up to 120-150 eggs, and up to 600 eggs over a lifetime. Eggs are about 1 mm long with a broad longitudinal groove, brilliantly white (Fig. 25). Moisture and warmth are required for egg development. The larvae feed on the organic matter of the substrate on which they live. They molt twice, passing through three larval phases (Figs. 26, 27). Their lifespan varies depending on environmental conditions (feeding intensity, warmth, moisture). The periods of metamorphosis of the house fly at various air temperatures. Developmental stages 16° Egg.............. Larval period ..... Pupa.......... . . Period from egg to adult fly.............. 36 hours. 21 days 18 days 40.5 » 40 hours. 26 days 21 days 46¹/₃ days 18° min. max. 27 hours. 10 days 12 » 23¹/₈ days 30 hours. 14 days 15 » 30¹/₄ » 20° 20 hours. 8 days 10 » 18¹/₆ days 30 hours. 10 days 11 » 22¹/₂ days 25° min. max. min. max. 12 hours. 7 days 7 » 14¹/₂ » 30° 20 hours. 8 days 17⁵/₆ » 8 hours. 12 hours. 5 days } 6 days | 4 days 15 » | i"]

and insect relationships; 2) positive role as natural "sanitarians" contributing to the rapid destruction of corpses. - H a r m of f l i e s: 1) Parasitizing humans, domestic and commercial animals; 2) extraordinary ease of practical transition to parasitic life by free-living flies (see Pseudoparasites, Myiasis); 3) transmission of certain blood parasites for which flies are specific, i.e., true hosts in which part of the developmental cycle of the transmitted parasite takes place; 4) mechanical transfer of various pathogenic bacteria, parasitic worm eggs, and protozoan cysts by the legs and proboscis of flies (see below); 5) economic harmfulness of flies due to their spoilage of meat, fish, cheese, and salted fish. The housefly (Musca domestica) is a domestic insect; it keeps to human dwellings, outbuildings, and households. In the dark, the housefly sits quietly. The lower lip of the housefly is transformed into a thick proboscis, the terminal lobes of which are covered with deep grooves with firm edges (Fig. 24). Due to this, the proboscis plays the role of a grater for solid food; material infected with bacteria (e.g., faeces) packs into the grooves when felt by the housefly. It takes food in liquid form, but can also eat solid food by dissolving it with regurgitated digestive juice. It frequently regurgitates ingested food and sucks it back up or leaves it on the substrate. Dried droplets together with the faeces of the housefly constitute those flyspecks with which houseflies "sit over" windowpanes and various objects. The housefly feeds on various human foods, pus, rotting waste, faeces, carrion, etc. Sense of smell plays a substantial role in the orientation of the housefly (search for food, oviposition sites). The housefly reproduces by egg-laying. The most favored place for laying eggs is horse manure, followed by human excrement, bird droppings, etc. Before pupating, housefly larvae often leave their habitat, moving into the ground or into places with a lower temperature. Over a year, the housefly produces up to 7-9 generations. A pair of flies can theoretically produce a total of 191,010,000,000,000,000,000 descendants from April to August. An adult housefly lives up to a month, rarely longer. Adult flies or their metamorphosis stages overwinter. Harm of the housefly. The fly is a universal mechanical vector of many pathogenic bacteria. The structure of the proboscis and legs of the housefly and its constant presence in the kitchen, at dumps, in dining rooms, in lavatories, etc., contribute to the contamination of the fly with infectious agents sticking into the grooves of the proboscis lobes. When wiping its wings and head with contaminated legs, the housefly infects the surface of its body. In addition, it devours various pathogenic bacteria with its food and ejects them outward in a virulent state when regurgitating or with faeces. By landing on food, utensils, human lips, getting into milk, etc., the fly contaminates these objects with bacteria located on or in it and thus contributes to the spread of corresponding diseases. The list of microorganisms spread by houseflies is large. The most important in epidemiological respects: Streptococcus pyogenes was isolated from urban houseflies; Diplococcus gonorrhoeae was detected on the legs of a housefly 3 hours after contamination with secretion; Staphylococcus pyogenes albus was isolated from the mucus-like cover of housefly eggs (as well as Calliphora vomitoria and Lucilia caesar) during egg-laying and from the body of an adult housefly; Staphylococcus pyogenes aureus does not lose its virulence when passing through the intestine of the housefly; Bacillus aerogenes capsulatus and Bact. coli commune were found on the surface of the body and in the intestine of the housefly; Bacillus anthracis spores survive in the organism of the housefly for up to 20 days; Bacillus dysenteriae are spread by houseflies, and a correlation is established between the number of houseflies and the growth of the epidemic; Bacillus enteritidis is found in urban flies; Bacillus leprae and Bacillus mallei can be spread by houseflies; Bacillus paratyphosus A and Bacillus paratyphosus B were isolated from urban houseflies; the latter microorganism can survive in the housefly for 11 days; Bacillus pyocyaneus is found in urban houseflies; if housefly larvae are fed food infected with this bacterium, the flies that subsequently hatch from them disperse the named rods with their excrement; Bacillus tuberculosis can be dispersed with the excrement of the housefly for 13 days; Bacillus tularensis can be alive in the organism of the housefly; Bacillus typhosus lives in the intestine of the housefly for up to 16 days; Vibrio cholerae can be carried about by houseflies on their legs or dispersed with their excrement within a day. Finally, the housefly transmits the causative agent of trachoma by contact and is an important agent in the spread of purulent conjunctivitis. The housefly is of particularly great importance in institutions for infants and severely ill patients in view of their helpless state. The housefly spreads pathogenic protozoa, namely, cysts of the dysenteric amoeba (which, however, quickly perish in dried fly faeces) and cysts of Giardia intestinalis; the transmission mechanism is the same as for bacteria: infection from faeces and transfer to food. The housefly plays an analogous role regarding the distribution of helminth eggs, such as ascarids, pinworms, hookworms, whipworms, etc. The housefly is an intermediate host of the chicken tapeworm Choanotaenia infundibulum and the equine nematode Habronema muscae (horse stomach), the larvae of which can cause granular dermatitis in horses. Flies can transport grain, cheese, and other mites on themselves, as well as pseudoscorpions. - The housefly is blamed for ¹/₂₀ of all cases of tuberculosis and ¹/₅ of all cases of typhoid fever; hence the renaming of the housefly into the typhoid fly propagated in the USA. The very substantial role of the housefly in infant mortality from summer infant diarrhea is undeniable. The harmfulness of the housefly has been taken into account in the USA and in some countries of Western Europe; an extensive and multifaceted struggle is already being waged against it, which is a necessary link in the cycle of measures against the spread of acute infectious intestinal diseases and other illnesses in the dissemination of whose causative agents this insect is guilty. Measures to combat the housefly can be directed at the adult form and at the metamorphosis stages; since the corresponding biotopes are different, these measures are also very diverse. A. Control of the adult housefly. 1) Mechanical protection of dwellings and especially hospitals and such buildings as barracks, etc., with screens in windows and vestibules at the entrance; protection of prepared food and provisions in homes, kitchens, pantries, stores, and especially on open retail trays with bell jars and gauze covers; clean maintenance and reliable washing of utensils; 2) catching flies on "Tanglefoot"—sticky paper smeared with catching glue made of rosin (2 parts) and castor oil (1 part) (melted and mixed); glass and screen fly traps; large Hodge traps are recommended for catching female flies arriving at oviposition sites (traps are installed near stables, cow barns, etc.; they are baited with putrid fish, meat, etc.); 3) poisoning flies with solutions of formalin (1 teaspoon per cup of water) with the addition of milk and sugar; 1% sodium fluoride; fly agaric tincture. B. Control of the larval stage is tied to the treatment of the housefly's location or the complete destruction of the same. 1) Eliminate the accumulation of kitchen waste from everyday life; pour out liquid parts; burn everything harder under the stove or in the furnace; 2) store waste in tight containers with a tightly closing lid on which a flytrap is installed for flies that could hatch inside the container; regularly clean it with the removal of waste outside the settlement boundary; 3) keep all husbandry clean, since man himself creates conditions most favorable for the development and life of houseflies and stable flies; hygienic maintenance of domestic animals is necessary; livestock housing with a solid floor, regular replacement of bedding once every 7-10-15 days; removal of manure into tight, well-closed and periodically cleaned manure pits; rapid drying of manure; laying manure in "ridges" on tamped areas with compaction of the surface and sides of the "ridge" by shovel blows (entails overheating of the interior of the pile to a temperature destructive to the housefly metamorphosis stage);

"self-purification" of manure from housefly larvae on special lattice platforms above cisterns with water and kerosene; before pupating, the larvae migrate downward from the manure heap and fall through the slots of the platform into the water (an installation for state farms and large agricultural enterprises); 4) rationally construct latrines with cleanable receivers, tight walls, a good door, and screens over various openings, and ensure hygienic use of toilets; 5) treat faeces (and manure) with chemicals: bleaching powder, milk of lime, iron sulfate, copper sulfate, potassium permanganate, and others; 6) organize a public and planned campaign against the housefly, since even heroic efforts by a few houses will not lead to the desired result; in addition, 7) widespread sanitary-hygienic propaganda among the population regarding the idea of fighting the housefly as a pest of enormous practical significance, which must be explained to the population using clear and illustrative examples (talks, lectures, exhibitions, sanitary corners, publication of brochures, posters, leaflets, slogans, propaganda in schools, in the Red Army, housing cooperatives, and so on). Natural enemies of the housefly: the fungus Empusa muscae, which usually affects it in autumn; the mite Holotaspis, various spiders (parasitic wasps Alysia manducator and others for Calliphora erythrocephala and other flies), the centipede Scutigera, larvae of the fly Hydrotea dentipes, chickens, rats, toads, and others.