Fly

As defined by entomologists, a fly (plural flies) is any species of insect of the order Diptera. These typically have one pair of true wings, with the hind wings modified into halteres. Flies are common amongst humans and some can cause the spread of serious diseases. The house-fly (Musca domestica) and mosquito are particularly common amongst humans. Other flies, such as the horse-fly (Family Tabanidae), can inflict painful bites. The larva of a fly is commonly called a maggot.

Flies rely heavily on sight for survival. The compound eyes of flies are composed of thousands of individual lenses and are very sensitive to movement. Some flies have very accurate 3D vision. A few, like Ormia ochracea, have very advanced hearing organs.

The diet of flies varies heavily between species. The horse-fly eats bits of flesh torn off of its prey, mosquitoes feed on blood and nectar, and the housefly eats a semi-digested liquid created by mixing-enzyme rich saliva with its food.

In addition to being an essential part of the food chain, some species of flies spread pollen, hasten the decomposition of plants, animals, and dung, and, in the case of about 5000 species of Tachina flies, eat other insects.

Maggots

The fly life cycle is composed of four stages: egg, larva (commonly known as a maggot), pupa, adult. The eggs are laid in decaying flesh, animal dung, or pools of stagnant water - whatever has ample food for the larva.

Some types of maggots found on corpses can be of great use to forensic scientists. By their stage of development, these maggots can be used to give an indication of the time elapsed since death, as well as the place the organism died. The size of the house fly maggot is 9.5-19.1mm (3/8 to 3/4 inch). At the height of the summer season, a generation of flies (egg to adult) may be produced in 12-14 days.

Maggot identification uses a classification called "Instar" stages. An instar I is about 2-5 mm long; instar II 6-14 mm; instar III 15-20 mm. These measure about 2-3 days, 3-4 days, and 4-6 days (for average houseflies or bottleflies) since the eggs were laid. By use of this data, plus other signs, the approximate time since death can be estimated by forensic scientists.

Various maggots cause damage in agricultural crop production, including root maggots in rapeseed and midge maggots in wheat. Some maggots are leaf miners.

Maggots are bred commercially, as a popular bait in angling, and a food for carnivourous pets such as reptiles or birds.

Use in medicine

Through the ages maggots have been used in medicine in order to clean out necrotic wounds. For more information, see Maggot therapy.

Fly-like insects

The word "fly" also refers to insects of various orders other than Diptera. Entomologists try to distinguish between true flies and other orders by hyphenating the names of true flies (house-fly, horse-fly, crane-fly), but giving the members of other orders unhyphenated names, either with two unconnected words (caddis fly, alder fly) or with a single, concatenated name (dragonfly, stonefly).

• firefly: Coleoptera: Lampyridae
• caddis fly: Trichoptera
• dragonfly and damselfly: Odonata
• butterfly: Lepidoptera
• stonefly: Plecoptera
• mayfly: Ephemeroptera
• sawfly: Hymenoptera: Tenthredinidae
• scorpionfly and hangingfly: Mecoptera
• alder fly, Dobson fly, and fish fly: Megaloptera

Rarest known fly

The world's rarest known fly family is Eurychoromyidae-Broad-headed Flies [1]

Flies in art and popular culture

In art, extremely life-like flies have sometimes been depicted in the trompe l'oeil paintings of the 15th century. An example is the painting Portrait of a Carthusian by Petrus Christus, showing a fly sitting on a fake frame. [2]

The 1958 and later remade in 1986 science fiction film The Fly revolves around the accidental merger of a human and a fly.

In 2001, Garnet Hertz produced an art project in which a complete web server was implanted into a dead fly.