The housefly, Musca domestica, is a fly of the suborder Cyclorrhapha. It is the most common of all domestic flies, accounting for about 91% of all flies in human habitations, and indeed one of the most widely distributed insects, found all over the world. It is considered a pest that can carry serious diseases.
In colder climates, houseflies survive only with humans. They have a tendency to aggregate and are difficult to dispose of. They are capable of carrying over 100 pathogens, such as those causing typhoid, cholera, salmonellosis, bacillary dysentery, tuberculosis, anthrax, ophthalmia, and parasitic worms. Some strains have become immune to most common insecticides.
House flies feed on liquid or semiliquid substances beside solid material which has been softened by saliva or vomit. Because of their large intake of food, they deposit feces constantly, one of the factors that makes the insect a dangerous carrier of pathogens. Although they are domestic flies, usually confined to human habitations, they can fly for several miles from the breeding place.They are active only in daytime, and rest at night, e.g., at the corners of rooms, ceiling hangings, cellars, and barns, where they can survive the coldest winters by hibernation, and when spring arrives, adult flies are seen only a few days after the first thaw.