fly

fly, name commonly used for any of a variety of winged insects, but properly restricted to members of the order Diptera, the true flies, which includes the housefly, gnat, midge, mosquito, and tsetse fly. All have sucking or piercing-and-sucking mouthparts and, except for a few wingless species, bear one pair of wings. The hind wings are reduced to knobbed balancing organs called halteres. All flies undergo complete metamorphosis, i.e., a four-stage development. The larvae, which occupy a wide variety of ecological niches, typically require a moist environment such as rotting flesh, decaying fruit, or the internal organs of other animals (see blowfly; botfly; fruit fly; tachinid fly). Adults often feed on nectar and plant sap, but some, such as the female horsefly and female mosquito, feed on blood; the adults of some species do not feed at all. A few species are found worldwide, often dispersed by humans; more than 16,000 species are found in North America. Many flies are harmful either as carriers of disease or as destroyers of crops. Some parasitize harmful insects. Some, such as the fruit fly, are important in laboratory studies. Flies are classified in the phylum Arthropoda, class Insecta, order Diptera.

Any of several dipteran species (botfly family Oestridae or the family Hypodermatidae), widespread in Europe and North America. The warble flies Hypoderma lineatum and H. bovis, also called cattle grubs or heel flies, are large, heavy, and beelike. They deposit their eggs on the legs of cattle. The larvae penetrate the skin, migrate through the body, and produce a lump, or warble, on the animal's back. Mature grubs emerge and drop to the ground to pupate. Warbles contain breathing holes, which reduce the hide's commercial value. One species (Oedemagena tarandi) is a reindeer pest that also causes economic losses.

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Any of about 21 species (genus Glossina, family Muscidae) of African bloodsucking dipterans that are robust, sparsely bristled, and usually larger than a housefly. They have stiff, piercing mouthparts. Only two species commonly transmit the protozoan parasites (trypanosomes) that cause human sleeping sickness: G. palpalis, found primarily in dense streamside vegetation, and G. morsitans, found in more open woodlands. The female requires a sufficient blood meal to produce viable larvae, but both sexes suck blood almost daily.

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Any member of the more than 85,000 species in the insect order Diptera (the two-winged, or “true,” flies), characterized by the use of only one pair of wings for flight and the reduction of the second pair of wings to knobs used for balance. Dipterans live in all habitats worldwide, including the subarctic and high mountains. They range in size from about 0.05 in. (1 mm) long (midges) to 3 in. (8 cm) long (robber flies). Dipteran larvae break down and redistribute organic materials, and both adults and larvae are a significant link in numerous food chains. Many species are annoying bloodsuckers, and several (e.g., housefly, mosquito, sand fly, tsetse fly) are vectors of disease. Other species cause great damage to agricultural crops. Seealso blowfly, crane fly, fruit fly, gnat, horsefly, leaf miner.

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Any of several species in the dipteran family Phlebotomidae (sometimes considered part of the family Psychodidae) with aquatic larvae that live in the intertidal zone of coastal beaches, in mud, or in wet organic debris. The genus Phlebotomus transmits the pappataci fever virus, and in parts of South America, Africa, and Asia it carries the protozoan parasites that cause kala azar, Oriental sore, espundia, and bartonellosis. The name is also used for species of the blackfly and biting midge families.

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or assassin fly

Any of about 4,000 species of predatory dipterans in the family Asilidae, found worldwide. Robber flies are the largest of all dipterans; some species are 3 in. (8 cm) long. Most have a dull-coloured, stout body resembling that of a bumblebee and a moustache of bristles between the large-faceted eyes. They use their long legs to capture insects in flight and hold them while eating; a fluid injected into the victim breaks down muscle tissue. A few species are serious pests of apiaries.

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Any member of the dipteran genus Tabanus or, more generally, of the family Tabanidae. These stout flies range from as small as a housefly to as large as a bumblebee. Sometimes called greenheaded monsters, horseflies have metallic or iridescent eyes. Adults are fast, strong fliers usually found around streams, marshes, and wooded areas. They may carry animal diseases, including anthrax, tularemia, and trypanosomiasis. The bites of the bloodsucking females can be painful, and a swarm may suck more than 3 oz (about 90 ml) of blood a day from an animal. Males feed on nectar, honeydew, and plant sap. Horseflies of the genus Chrysops, usually called deerflies, are smaller and have dark markings on the wings.

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Any dipteran species of two families: large fruit flies (Trypetidae) and small fruit flies, or vinegar flies (family Drosophilidae; see drosophila). The larvae feed on fruit or other vegetation. The adults' wings are banded or spotted with brown. Many species attack cultivated fruits, sometimes causing enough damage to create significant economic loss. Some species are leaf miners; others burrow in plant stems. Well-known fruit-fly pests include the Mediterranean fruit fly and the apple maggot of the U.S., the Mexican and Oriental fruit flies, and the olive fruit fly of the Mediterranean region.

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In general, almost any small flying insect. In entomology, the term refers specifically to the approximately 120,000 species of two-winged, or “true,” flies (dipterans). Other insects called flies have wing structures that differ from that of dipterans.

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Harmless, slow-flying dipteran (family Tipulidae) usually found around water or abundant vegetation. It ranges in size from tiny to slightly over 1 in. (2.5 cm) long. Larvae of the range crane fly (Tipula simplex) are called leatherjackets because of their tough brown skin. In northern latitudes a wingless crane-fly species is found on snow. The crane fly is also called daddy longlegs in English-speaking countries other than the U.S. (in the U.S., daddy longlegs refers to an arachnid).

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Any member of about 7,000 species of mothlike aquatic insects (order Trichoptera) found worldwide, usually in freshwater habitats but sometimes in brackish and tidal waters. Generally dull brownish, caddis flies have long antennae and hairy wings that fold rooflike over the abdomen. They feed primarily on plant juices and flower nectar, though a few are predaceous. Many caddis-fly larvae construct a portable case from grains of sand, bits of shells, and plant debris glued together by a sticky substance they secrete. This case surrounds the larva's abdomen while it matures. Caddis flies are important to freshwater ecosystems because they clean the water by consuming plant and animal debris and serve, as larvae and adults, as an important food for fish, particularly trout.

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Any member of several dipteran families with beelike adults and larvae that are parasitic on mammals. Some species are serious pests of horses, cattle, deer, sheep, rabbits, and squirrels, and one species (the human botfly) attacks humans. Adults of several species lay many eggs (nits) on the host's body, and the emerging larvae penetrate its skin. The larvae reemerge through the skin, then mature into egg-laying adults. In the New World tropics, the botfly's infestation of cattle has led to loss of beef and hides. Seealso warble fly.

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Any member of the dipteran family Calliphoridae, including the screwworm and the bluebottle, greenbottle, and cluster flies. Metallic blue, green, or bronze, and noisy in flight, blowflies resemble the housefly in size and habits. The larvae usually feed on decaying flesh and sometimes infest open wounds. They may help prevent infection by cleaning away dead flesh, but may also destroy healthy tissue. Blowflies were once used to treat gangrene and a human bone disease and were used in World War I to clean soldiers' wounds. Some species seriously hurt or kill livestock by massive infestation or by carrying diseases such as anthrax, dysentery, and jaundice.

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Any member of the insect family Simuliidae, comprising 300 species of small, humpbacked dipterans found worldwide. Usually black or dark gray, the blackfly has short mouthparts adapted for sucking blood. The females bite and are sometimes abundant enough to kill chickens and even cattle. Some species carry worms capable of causing human disease, including river blindness. In subarctic regions blackflies may be so numerous that human habitation is impossible.

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or Med fly

Fruit fly (Ceratitis capitata) proven to be particularly destructive to citrus crops, at great economic cost. The Med fly lays up to 500 eggs in citrus fruits (except lemons and sour limes), and the larvae tunnel into the fruit, making it unfit for human consumption. Because of this pest, quarantine laws regulating fruit importation have been enacted worldwide.

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See Aircraft flight control systems#Fly-by-wire (FBW) control systems