The housefly (Musca Domestica) is a common dipterous insect of the family muscidae, which constitutes a major nuisance and hazard to public health. Female houseflies often deposit more than 100 eggs at a time on decomposing organic wastes such as horse manure or fermenting garbage. The young adult houseflies, when they fly from their filthy breeding sites into human habitations, may carry on their feet many million bacteria. If they contaminate human food, they can cause bacillary dysentery. In this way, flies act as vectors of cholera, typhoid fever, amoebic dysentery, poliomyelitis, anthrax, eggs of parasitic worms, and cysts of Entomoeba histolytica and other organisms.
The housefly is virtually cosmopolitan and comprises about 90% of all flies occurring in human habitats. It is a health hazard in virtually all human communities, ranging in size between small farms and large cities, wherever food substances suitable for the development of its maggots are allowed to accumulate.