The common house fly (Musca domestica) is an unwelcome pest at any time of the year. These insects are found throughout the world except in Antarctica and a few remote islands. House flies belong to the family Muscidae which also includes other pests like the stable fly, the face fly, the horn fly, and the tsetse fly.
Adult house flies are about 6mm in length with one pair of membranous wings and one pair of halteres. They have gray bodies with four darker stripes running longitudinally along the dorsal side of the thorax. The mouthparts, which are adapted for sponging-lapping, retract against the head when not in use.
House flies breed in damp, filthy places such as rotting garbage, stagnant water, and animal refuse. The female can lay five to six batches of eggs. Each batch may contain 75-120 oval white eggs. The eggs hatch in 10-24 hours after deposition and grow to mature larvae in 5 or 6 days. Under ideal conditions, a new generation develops every 10-12 days. Adult males live about 15 days; adult females live about 26 days if they have access to milk, sugar, and water. The adults suck liquids containing sweet or decaying substances. Solid food, like sugar crystals, are first liquified with saliva before they can be ingested.
Flies pose a serious threat to human health. Because they breed in fresh excrement and fermenting vegetation, they seve as a primary vector for the spread of bacterial, protozoal, and viral pathogens. Diseases linked to transmission by flies include ameobic dysentery, tuberculosis, typhoid fever, anthrax, poliomyelitis and cholera. Many poor countries suffer the wrath of fly-borne diseases despite eradication efforts. House flies can also serve as intermediate hosts for poultry tapeworms and parasitic roundworms that infest large animals.
Control of houseflies is best accomplished through sanitation -- cleaning up garbage, manure, etc. where the larvae develop. Window screens and positive air pressure (fly fans) can be used to keep the adult flies out of homes and businesses. Predatory mites and parasitic wasps show good potential for biological control of house flies around confined livestock and in poultry houses.