Facts About Houseflies

Anatomy

• The housefly is a gray, winged insect, about one-fourth of an inch in length. Like many insects, it has three three body segments --- the head, thorax and abdomen. Four longitudinal stripes run the length of its thorax, and its body is covered with small hair-like projections. Its six legs are likewise covered with these hairs. It has two pairs of wings, as well as a smaller pair of stabilizing structures called haltera behind the wings. The fly's compound eyes, positioned on the sides of its head, contain thousands of individual lenses. They allow the fly to detect movement at an extremely wide angle.

Life Cycle

• Female house flies can carry up to 500 eggs. They deposit the eggs, in batches of 75 to 150, among decaying organic matter such as garbage and feces. This matter becomes the larvae's food. The eggs hatch within a day or two into tiny, white, legless maggots. After three moltings, the maggots burrow into a dry, cool place and form pupae, which are hard shells within which they transform into adult flies. Once they emerge from their pupae, the flies cease to grow. Thus, the size of a fly is solely a function of its nutritional intake as a larva. Adult flies mate sexually. The male injects sperm into the female's abdomen one to two days after emerging from their pupae.

  The entire lifecycle can be completed in a week, but usually it takes about three weeks. Warmer temperatures quicken the flies' developmental processes. Likewise, adults live about two and a half weeks during the summer, but can live for up to three months under colder conditions.

Habits

• Houseflies are typically active only in the daytime. They take their rest in ceilings, wiring, trees, shrubs and other hidden areas. Houseflies eat through a proboscis that extends from and later retracts into their heads. They can only eat fluids, though, so to ingest something, they must first first liquefy it with their own saliva. They do this to a variety of moist organic matter, including decaying foods, feces, mucus and flesh. In colder climates, houseflies survive only in human domiciles.

Risks and Control

• Houseflies are known to carry parasites, bacteria and viruses that they pick up from garbage and feces. They transmit these pathogens on their body hairs, mouthparts, saliva and feces. Fly populations are especially difficult to control in agricultural facilities, where they congregate in great number around the manure of livestock.

  The most effective long-term method of reducing fly infestation is proper sanitation. Sanitary measures, such as covering trash cans tightly and disposing of food quickly, will preclude flies from feeding. Sealing all entrances to the home, whether with mesh screens over the windows or weather stripping around doorways, can help prevent houseflies from entering. Existing fly infestations can be controlled with fly paper or with ultraviolet light traps, which lure flies in and then kill them.