Houseflies most likely carry and transmit at least 65 diseases, some of which include typhoid fever, dysentery, cholera, poliomyelitis and yaws. The flies also carry anthrax, tularemia, leprosy and tuberculosis.
Flies transmit diseases they carry because they automatically regurgitate and excrete wherever they rest. Organisms are also carried in their hairs and mouth parts. Disease-transmitting organisms are picked up by flies when they visit places such as dumps, sewers and garbage heaps. The flies also pick up organisms when they feed on fecal matter, discharge from wounds and sores, sputum and a wide variety of decaying matter.
Four basic principles of pest management, sanitation, exclusion, nonchemical measures, and chemical methods, are used to control flies. Sanitation requires limiting the food sources of flies by preventing materials such as manure, garbage, grass clippings, weed piles and other decaying organic matter to build up. Exclusion is accomplished by closing any openings that would allow flies to enter a home or building. It includes using screens on windows and doors, and caulking or plugging any small openings that lead inside.
Nonchemical measures include devices such as ultraviolet light traps, sticky fly traps, fly swatters and baited fly traps to kill flies that make their way inside. Methods used for chemical control consist of spraying exterior applications of insecticides by a licensed pest control expert. Large numbers of flies inside the home are controlled using aerosol sprays designed to kill flying insects.