Muscidae

Adult muscids are 4-8 mm long and have a wing span of 13-15 mm; they are strong flyers. The body is usually blackish gray to black and their sponging mouthparts are well developed. The eyes are widely separated in the female and usually contiguous in the male. Females deposit eggs, but some species deposit first-stage larvae on suitable substrates. Larvae are smooth, cylindrical, and anteriorly tapered; larvae ofFannia have lateral processes. Larvae are 6-8 mm long, and feed as scavengers, but some are carnivorous on other insects in their food substrate. Development is rapid and overwintering may be as an adult, full-grown larva, or pupa. There are many domestic and peridomestic pests in this family. Most of the common species are cosmopolitan.

Pest status is based on their association with organic waste material and the transfer ofpathogenic organisms to humans and food, and on the ability of some species to bite and suck blood. Many of these flies, especially the Musca species, do not bite, but are simply a nuisance around animals and humans. Muscids travel 2-3 km from their breeding site to find food or habitats for oviposition. Hydrotaea larvae are primarily saprophagous (exceptfor the final instar), and the adults are mostly sweat flies with a preference for mammalian blood. Muscids in the urban environment often utilize garbage and excrement as a food source, and they have been associated with humans for centuries. Several species are active throughoutthe year, but develop slowly in cold months.

Durnfly, Dasyphoracyanella Adults are about 9 mm long and greenish blue; the thorax has two longitudinal dark stripes. This metallic muscid looks like a bluebottle fly (Calliphoridae). Eggs are laid in batches of 25-30 eggs, and deposited below the surface of cow dung in fields. Hatching occurs in 1-3 days. Larval development is completed in about 28 days, and the pupal period lasts 21-28 days. Adults are active from May to November, after which they hibernate indoors in buildings. They seem to prefer large and open structures, such as barns. This species is distributed in the UK and northern Europe.

Little house fly, Fannia canicularis (Fig. 7.1 i) Adults are about 6 mm long and the body is blackish gray with brownish-yellow markings on the abdomen; the thorax has three brown longitudinal stripes. Full-grown larvae are 7-8 mm long and yellowish white to reddish brown, and slightly flattened; there are projections on the lateral and dorsal aspect of most segments. The anterior end is tapered and the posterior end is rounded. The anterior spiracles have six or seven lobes; the posterior spiracles are on small tubercles. Eggs are laid directly on the substrate, and are morphologically adapted for wet conditions. Hatching is in 30-40 h during warm temperatures of summer, and 3-4 days at other times. Development is complete in 8-10 days, and the pupal period lasts 9-10 days. Full-grown larvae leave the substrate and move to dry locations to form the puparium. Adults overwinter in protected locations outdoors and indoors, but they usually overwinter as pupae in the soil. In temperate regions, overwintering adults become active in late February, and emergence from overwintering pupae usually occurs in March. Natural populations of F. canicularis and other closely related species occur in nests of bees (Bombus spp.), decaying snails, and vegetation, and sites that have nitrogenous droppings and rich, decaying organic material. Males and females are attracted to honeydewand are often found ataphid-infested trees and shrubs. This fly is cosmopolitan, and it is one of the most abundant of all the flies associated with humans. They are found indoors and out, associated with excreta, vegetables, fruits, and beverages. It is usually more abundant in spring and fall; high temperatures and dry breeding media suppress populations.

Latrine fly, Fannia scalaris Adults are about 7 mm long. The thorax and abdomen are bluish black, and the abdomen has a dark median stripe. The middle tibia has a tubercle near the middle, and the coxae on the midlegs have two apically bent setae. Full-grown larvae are 6-8 mm long and may be brown to yellowish brown; the body is flattened. There are long lateral projections on all segments, and the projections on segment 8 are longer than the length of segment 7 and 8. Eggs are deposited directly on the substrate; hatching occurs in about 24 h. Development is completed in about 6 days, and the pupal stage lasts about 9 days. This species is cosmopolitan and it is associated with animal and human excrement. It resembles F. canicularis and has similar larval morphology and habits. The life cycle is similar to F. canicularis;andthelarvaeoccur in excrement, cadavers, bird nests, and decaying fungi. When it occurs indoors it is usually associated with human or animal feces.

Other Fannia Several species are found in the urban environment and associated with human or undisturbed habitats. F. benjamini is a pest in suburban and recreational areas of California; here they annoy people by their attraction to perspiration and mucous secretions. F.femoralis is a small fly and it occurs throughout the USA and northern South America. F. incisurata occurs in North America, Canada, and from Iceland to Japan and North Africa, and from Mexico and neotropical regions. It is common in excrement and wet substrates. F. leu-costica is found in North America and Europe, and it prefers dry excreta.

Sweat fly, Hydrotaea metorica Adults are 4-6 mm long; the males are shining black, females are dull gray. Wings are light gray and the halteres are black. The abdomen is dull gray with a median black band formed from connected triangles. Eyes of the male are narrowly separated. The full-grown larva has transverse rows of setae on abdominal segments 2-8; there are three prospiracular lobes, and the posterior spiracles are weakly sclerotized. Larval development takes about 39 days in summer. The puparium is pale orange, and slightly shining; pupal respiratory horns are very long, and bright orange red. Overwintering is in the larval stage. In Europe there are two generations per year, with adults appearing in May and June, and in August and September. Adults are attracted to perspiring cattle and humans. This species is distributed from Spain and Majorca to northern Scotland, to Sweden and Finland eastwards to Siberia and south to Israel. In North America it occurs from Arizona and New Mexico to British Columbia and Maine. It is a pest in Siberia, where it enters houses to feed on perspiration and blood. A related species, H. pelluscens, breeds in cow dung and the adults are a persistent sweat-fly around humans.

Hydrotaea dentipes Adults are about 6 mm long and shining black to dull gray. Full-grown larvae are about 13.6 mm long and yellowish white; the posterior spiracles are reddish brown and elevated. Eggs are laid in batches beginning in late March; fecundity is 170-200 eggs. Development to the third-stage larvae requires 1-2 days, and this stage is predatory on other insects in the substrate. Third-stage larvae complete development in about 7 days, and the pupal period lasts 2-3 weeks. Development is completed in 23-25 days at 16-28 ° C. There are usually two generations per year. In the agricultural environment, larvae breed in organic material, including dung of pig, horse, cow, and humans. In the urban environment larvae are in rubbish dumps, cesspools, carrion, and manure heaps. Third-stage larvae are predators of Musca domestica, Stomoxys calcitrans, and the larvae of other pest species of flies in animal dung. This species is nearly cosmopolitan, exceptfor subarctic tundra and desert regions.

Facefly, Musca autumnalis Adults are 4-6 mm long and resemble the house fly. Eyes of the male face fly are nearly contiguous at the top; in the house fly they are not. Eggs are laid singly or in batches of 7-36, and females produce four or five batches in their lifetime; fecundity is about 230 eggs. Hatching occurs within 24 h. Larvae complete development in 5 days at 20 °C, and 2.5 days at35-40 °C. Full-grown larvae move to drier sites to form the puparium; the pupal period is 7-10 days. Adults live about 10 days, but those of the last generation live for several months. Adults are attracted to undisturbed cattle excrement within 2 h after deposit; they usually do not visit manure that is in piles, or mixed with straw, hay, or urine. Face fly fecundity is affected by the entomoparasitic nematode Paraiotonchium autumnalis. This nematode is host-specific and infests face fly larvae in dung. Infected adult flies have one or more nematodes in their hemocoels, and eventually nematode larvae invade and disrupt the ovaries of female flies. M. autumnalis is native to Europe, western Asia, and eastern Africa, but now occurs in Canada and northern USA.

Face flies hibernate in large numbers as unmated adults in buildings, mammal burrows, and in other protected places, whether heated or not. Both sexes exhibit adult facultative diapause, which is characterized by fat hypertrophy and cessation of ovarian development. Overwintering groups have a sex ratio of 1:1. Mating occurs after they emerge from the overwintering site; females then disperse for egg-laying. Face flies tend to aggregate and overwinter in the same sites year after year; perhaps they are stimulated by or attracted to volatile chemicals remaining in the habitat. However, houses with continued problems with overwintering face flies may not be in areas where there are herds of cattle. The adults of M. autumnalis can fly long distances to find or return to suitable hibernation sites.

Mild winter temperatures may limit their overwintering ability, especially along the Atlantic and Gulf Coast of the USA. Warm temperatures in winter may exhaust the metabolic reserves of post-diapausing flies, and reduce the number ofreproductive adults the following spring. Fluctuations in populations may be linked to a variety of environmental factors.

House fly, Musca domestica (Fig. 7.1h; Fig. 7.5a, b) Adults are 4-8 mm long and there are four stripes lengthwise on the thorax; the wings are translucent. Full-grown larvae are 12-13 mm long and yellowish white; the body is smooth and slightly shiny. There is a patch of small spines ventrally between abdominal segments 1 and 7, but absent on the thoracic segments. Anterior spiracles are yellowish white and have six or seven orange-yellow openings, but not on distinct lobes. The posterior spiracles have a complete peritreme and the 3 openings are sinous. This is probably the most widely distributed insect pest, and it is associated with humans around the world. It is most abundant during the warm season, but it may overwinter as adults in temperate regions and remain a pest throughout the year. In North America and Europe it is common from July through September; in South America and Australia it is common from October through February and March.

Eggs are deposited in batches of 75-150; they are usually piled into masses and there are several deposits at intervals of 3-4 days. Females may depositas many as 21 batches of eggs for 31 days after emergence. Females need mate only once to fertilize all the eggs laid in their lifetime. Under warm conditions the eggs hatch in 8-12 h. Larvae complete development in about 5 days, and the pupal period lasts about 4 days. Larvae spend 3-4 days in a migratory stage prior to forming the puparium. During this time, they usually move to a substrate that is drier than their feeding place. Adult flies live about 30 days during warm months, but this may extend to 60 days. Overwintering occurs as a larva, pupa, or an adult; in protected and moist locations, adults may live from October to April. The potential distance for adult dispersal is 27-1080 m in urban habitats, and 270-1530 m in rural habitats, but a distance of 9 km has been recorded. In urban localities, the usual distance traveled by M. domestica is about 400 m. Adults are inactive at temperatures below 7.2 °C, and temperatures below 0 °C are lethal. They remain alive for long periods at temperatures in the range of 10-26.6 °C.

Adult activity is diurnal, and reaches a peak between 14:00 and 16:00 h, which usually corresponds to the hottest and driest portion of the day. Adults are inactive and at rest during night, but they will move to artificial light during the day or night. Flightoccurs atan air temperature ofii.6 °C, and reaches maximum intensity at 32.2 °C. Above 32.2 °C, flight declines rapidly and ceases at the thermal death point of 44.4 °C. High and low temperatures are lethal to M. domestica adults when humidity is high. Adults live longest at 15.5 °C and 42-55% RH, and they require two or three feedings of liquid food each day. Their sponging mouthparts restrict them to utilizing liquids or foods soluble in salivary secretions. Adult food sources include milk, sugar, blood, and other substances, such as feces and decaying organic matter; a source of water is also important. Adult flies do not emerge from puparia when exposed to temperatures below 11 °C for 20 days, or 8.8 °C for 24 h.

Larvae of M. domestica survive best in compost-like mixtures of decaying vegetable material enriched with dung or animal material, which is the basic formula for household garbage. Feeding larvae prefer a temperature range of30-35 °C. Larvae prefer dung of pigs, horses, and humans to that of cows, which is preferred by the closely related species M. autumnalis. The long-term association between M. domestica and the production of garbage in the human household gives this species a secure future in the urban environment.

Morphological differences exist between M. domestica populations throughout the world. M. d. nebulo and M. d. vicina, sometimes called the Egyptian house fly, are two notable subspecies. M. d. nebulo is a common house fly throughout the Ethiopian ecological region, and is found in outdoor markets and houses, and is the most common household fly in southern India. M. d. vicina breeds primarily in horse dung in urban areas, and in donkey dung in rural areas.

In the development of insecticide resistance, the house fly is one of the most mutable pest species. It has the ability to develop resistance to representatives of all the major classes ofchemical insecticides. All ofthe resistance-related mechanisms, which include enhanced metabolic degradation, diminished target site sensitivity, reduced rates of cuticular penetration, sequestration of toxicants, and behavioral changes enabling avoidance oftoxic residues, have been demonstrated in this species. In many cases, several of these resistance factors exist concurrently.

Bazaarfly, Muscasorbens Adults are about 6 mm long and the thorax is grayish black. The female abdomen is grayish black; the terminal abdominal segments of the male are yellowish brown. Full-grown larvae are about 12 mm long and yellowish white; the puparium is pale orange. Eggs are laid closely packed and cemented together in rows, usually in batches of about 30. Preferred oviposition sites are human excrement, garbage, carrion, and other decaying organic material. Substrates may attract numerous females. As manyas 42 000 larvae have been collected from 1 kg of human feces, which indicates that several females deposited eggs at this site. Females usually feed for a short time on the excrement substrate after ovipositing. Development takes 2.5 days at 23 °C, and about 15 days at 17-20 °C.Pupariaare usually formed in dry locations away from the larval feeding site. Adults live 14-20 days, but the life span may be longer atlower temperatures. This species is widely distributed in the western hemisphere tropics and subtropics, and in Africa, the Middle East, India, and from China to Australia. It is a common household fly pest in India. The adults occur at outdoor markets and bazaars, food stores, and houses year-round; there is a population peak in the spring and one at the end of summer.

Other Musca This large genus has over 3900 species worldwide, and many are associated with rural and urban areas. M. fasciata, M. vetustissima, M. vitripennis, and M. patoni are attracted to sores orany body secretion. The bushfly, M. vetustis-sima,isamajorpestovermuchofAustralia, M. biseta is an equal pest in Africa, and M. conducens enters houses in India. These species commonly settle in large numbers on people living in unsanitary conditions, and eventually individuals habituate to the presence offlies crawling on the face and head. M. osiris and M. tempestiva breed in cow dung and the adults are troublesome sweat flies outdoors in deserts and villages; M. osiris extends across north Africa to Egypt, and north to Suffolk, UK; M. tempestiva extends from Africa to China and Japan, and north to the Channel Islands.

False stable fly, Muscina stabulans Adults are 8-10 mm long and dark gray; the abdomen is reddish brown. This species has sponging mouthparts, and the adults do not bite. The larval stages breed in a variety of material, including human excrement, manure, and garbage. Eggs are deposited on tainted food, and 140-200 eggs may be deposited in 2-3 days. The first- and second-stage larvae are primarily saprophagous, but the third stage is a predator on larvae of other flies in the substrate. Development is completed in 15-25 days, and there are two or three generations each year. Overwintering is in the pupal stage. Natural populations occur in bird and animal nests in natural areas. Other related species, such as Muscina assimilis and M. pabulorum, have similar habits, but do not enter houses. This species is nearly cosmopolitan. The pest status of M. stabulans is based on the large numbers that can breed in the urban environment, and the abundance of adults indoors.

Bronze dump fly, Ophyra aenescens Adults are about 5 mm long and yellowish green. Mating occurs on the second day after emergence. Eggs are deposited in batches of about 74 and hatching occurs in aboutnh; fecundity is 276-438 eggs. Development is completed in about 5 days, and the pupal period is 4 days. The life cycle is completed in about 14 days at 27 °C. Males live 15-18 days and females live 20-35 days. The adults are capable of dispersing about 6 km from their breeding site. Females are attracted to carrion, animal manure, and human feces. Larvae are saprophagous during the first stage, but second- and third-stage larvae are predators and attack other fly larvae in the substrate. This species has been used as a biological control agent for Musca domestica in commercial poultry houses, and urban refuse disposal sites. It first appeared in Spain in 1966, and in Germany in 1971, in Denmark in 1972, and in the 1970s it spread through central Europe. This species is nearly cosmopolitan in refuse disposal sites. Adults are commonly found indoors in the southern part of its range.

Blackdumpfly,Ophyraleucostomata Adults are 4-5 mm long, black and glossy; they have few setae on the body and the wings are slightly opaque. Adults prefer to rest on vegetation around breeding sites, and in northern regions they remain in the sunlight. Larvae develop in decaying organic matter, including human and livestock feces, and household kitchen garbage. First-stage larvae are saprophagous, but second- and third-stage larvae are predators and attack other fly larvae in the substrate. They are common predators of Musca domestica larvae, and may kill 2-20 maggots per day. O. leucostomata is distributed in North America and Europe.

Other Ophyra Dump flies are distributed around the world; they are often found around garbage disposal sites and are often abundant in urban areas. The adults of some species readily move indoors, while others remain outdoors. O. anthrax is widely distributed in the Caucasus and Central Asia, and occurs around toilets, animal carcasses, and in houses. O. capensis is found in southern Europe and has habits similar to O. leucostoma. In the Australian region, O. nigra is closely associated with humans. O. ignava larvae have been recorded from corpses of animals and humans (at the phase of ammoniacal fermentation).

Stable fly, stomoxys calcitrans Adults are 4-6 mm long and they have a hardened proboscis projecting from the lower part of the head. Both males and females suck blood. Full-grown larvae are 11-12 mm long and the body is yellowish white and smooth. The ventral bands between abdominal segments 1 and 7 have ridges and scattered setae. The anterior spiracle is light yellow and has five or six lobes; posterior spiracles have a reduced periterme and irregular-shaped openings. Adult feeding habits are linked to domesticated animals and occasionally humans. Larval feeding habits are varied, and they may not always include feeding on dung. In warm climates adults remain in the open, but in temperate regions they are usually in animal stables or other protected sites. S. calcitrans is cosmopolitan in temperate and tropical regions, and a common pestoflivestockand humans. This species probably originated in a warm climate, and it became associated with humans when animals were domesticated and stables were built. It is a biting fly pest in the urban habitats, and along coastal areas where its breeds along beaches (sometimes itis called the beach fly).

Eggs are laid in batches of 40-80; fecundity is about 600 eggs. Hatching occurs in 12-24 h during summer; in fall it is in 1-4 days. Development time varies with temperature, and may be 12 days to over 30 days. Full-grown larvae move from the substrate to dry locations to form the puparium. The pupal period is 2-20 days, depending on temperature. Adults live about 30 days, and males usually live longer than females. Adults are active from May to October, and they are pests in late summer and fall. They are strong flyers and may be found indoors as far as 1 km from cattle. They seek shelter at night, but do not bite after dark. Feeding on animals is preferred; attacks on humans are usually accidental except along beaches.

Other stomoxys The other Stomoxys species common in peridomestic habitats in Africa are: S. niger niger, S. n. bilin-eatus, S. inornatus, S. taeniatus, and S. varipes. The diurnal activity of S. n. niger includes a peak of activity in the morning between 08:00 and 11:00 h, and a peak in the evening between 17:00 and 18:00 h; there is little activity during the middle of the day.

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