Note: Information is dated. Do not rely on it.Fly. The word fly is generally used to designate an insect of the order Diptera. Members of this order have two membranous wings without wing covers. In place of the hind pair are two knobbed threads called balancers, which are supposed to assist the insect in maintaining equilibrium while in flight. The common house fly, Musca domestica, is found wherever man is, and in hot weather causes a great deal of annoyance. It is furnished with a suctorial proboscis, from which, when feeding on dry substances, it exudes a liquid, which, by moistening them, fits them to be sucked. From its feet being beset with hairs, each terminating in a disc which is supposed to act as a sucker, it can walk on smooth surfaces, as a ceiling, even with its back down. The female lays from 120 to 160 eggs in horse manure. From the eggs come little maggots which molt twice and become full grown in from five to seven days. They then pass into the pupa stage from which the perfect fly emerges about a week later. Flies act as scavengers, consuming much filth that would otherwise decay and become offensive. They also carry germs from sores or human excreta to articles of food or to healthy people and thus disseminate disease. Typhoid fever, diphtheria, and tuberculosis are among the diseases so transferred.