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House Fly
Musca domestica is a cosmopolitan companion of humans and domestic animals. House flies are less than one-half inch in length. They are gray, with four dark stripes down the dorsum of the thorax. House flies have sponging mouthparts and can ingest only liquids. However, they can eat solid food (e.g., sugar, flour, pollen) by first liquefying it with their saliva.

Damage

House flies cannot bite; however, they have been demonstrated to mechanically transmit the causative agents of diarrhea, cholera, yaws, dysentery, and eye infections. Flies are also implicated as mechanical vectors of Shigella and Salmonella, the latter being a pathogen responsible for food poisoning.

Biology & Life Cycle

Under favorable conditions the house fly can reproduce prodigiously because of its short generation time and the large number of eggs produced by each female–several batches of about 150 eggs. Eggs are laid in warm, moist, organic materials such as manure, garbage, lawn clippings, decaying vegetables and fruits, or soils contaminated with any of these materials. Under good conditions the eggs hatch in less than a day. The cream-colored larvae can then complete development within a week. Larvae of the house fly have a blunt posterior end and taper to a point at the head end. Larvae seek drier areas to pupate. Pupation lasts 4 to 5 days and a generation can be completed in less than 2 weeks; during the summer 10 to 12 generations can develop.

Control

Most measures to control house flies are nonchemical. Mechanical control remains the first line of defense against house flies as in almost all cases where flies are seen inside a building they have entered from the outside. For commercial facilities, air doors can provide effective barriers to fly entry, and light traps attract any of those that still manage to get in. A fly swatter can be used effectively against the stray individual that finds its way into a house. Outdoors, regularly remove (at least twice a week) and dispose of organic waste, including dog feces, to reduce the attractiveness of a site to flies and limit their breeding areas. Garbage should not be allowed to accumulate and should be kept in containers with tight-fitting lids. In general, poor exclusion and lack of sanitation are the major contributors to fly problems. Fly papers or ribbons are effective at eliminating a few flies, but are not effective enough to manage heavy infestations. Selective use of insecticides against house flies is one component of a total fly management program but should only be used after all possible nonchemical strategies have been employed. To kill flies indoors, a nonresidual pyrethrin space spray or aerosol can be used. Fly baits used in trash areas are effective in reducing the number of flies around buildings if good sanitation practices are followed.