Fly (formed on the root of the supposed original Teut. fleugan, to fly), a designation applied to the winged or perfect state of many insects belonging to various orders, as in butterfly (see Lepidoptera), dragon-fly (q.v.), may-fly (q.v.), caddis-fly (q.v.), &c.; also specially employed by entomologists to mean any species of the two-winged flies, or Diptera (q.v.). In ordinary parlance fly is often used in the sense of the common house-fly (Musca domestica); and by English colonists and sportsmen in South Africa in that of a species of tsetse-fly (Glossina), or a tract of country (“belt”) in which these insects abound (see Tsetse-Fly).
Apart from the house-fly proper (Musca domestica), which in England is the usual one, several species of flies are commonly found in houses; e.g. the Stomoxys calcitrans, or stable-fly; Pollenia rudis, or cluster-fly; Muscina stabulans, another stable-fly; Calliphora erythrocephala, blue-bottle fly, blow-fly or meat-fly, with smaller sorts of blue-bottle, Phormia terraenovae and Lucilia caesar; Homalomyia canicularis and brevis, the small house-fly; Scenopinus fenestralis, the black window-fly, &c. But Musca domestica is far the most numerous, and in many places, especially in hot weather and in hot climates, is a regular pest. Mr L.O. Howard (Circular 71 of the Bureau of Entomology U.S. Dept. of Agriculture, Washington, 1906) says that in 1900 he made a collection of the flies in dining-rooms in different parts of the United States, and out of a total of 23,087 flies, 22,808 were the common house-fly. Its geographical distribution is of the widest, and its rapidity of breeding, in manure and door-yard filth, so great that, as a carrier of germs of disease, especially cholera and typhoid, the house-fly is now recognized as a potent source of danger; and various sanitary regulations have been made, or precautions suggested, for getting rid of it. These are discussed by Mr Howard in the paper referred to, but in brief they all amount to measures of general hygiene, and the isolation, prompt removal, or proper sterilization of the animal or human excrement in which these flies breed.
