housefly, common name of the fly Musca domestica, found in most parts of the world. The housefly, a scavenger, does not bite living animals but is dangerous because it carries bacteria and protozoans that cause many serious diseases, e.g., typhoid fever, cholera, and dysentery. The housefly feeds by depositing a drop of digestive liquid on its food, which may be garbage, excrement, or other filth. Although most of the liquid drop is sucked back again through the insect's tubelike lower lip, or labium, a residue remains that may contain disease-causing organisms from previous meals. Disease is also transmitted on the fly's sticky foot pads and hairy body. Each female lays from 100 to 200 eggs in the garbage or manure on which the white larvae feed. With favorable temperatures, one generation or more per month may be produced. Metamorphosis is complete, i.e., development is in four stages. The housefly is classified in the phylum Arthropoda, class Insecta, order Diptera, family Muscidae. For methods of control see bulletins of the U.S. Dept. of Agriculture.

Common dipteran (Musca domestica), accounting for about 90percnt of all flies in human dwellings. The adult is dull gray with dirty-yellowish areas on the abdomen. Body size ranges from 0.2 to 0.3 in. (5–7 mm), and the conspicuous compound eyes have some 4,000 facets. Because it has sponging or lapping mouthparts, it cannot bite. It is a problem wherever decomposing organic waste and garbage are allowed to accumulate. Its feet may carry millions of microorganisms, some of which cause diseases, including cholera, dysentery, and typhoid. Some insecticides are effective, but houseflies have developed resistance to others.

Learn more about housefly with a free trial on Britannica.com.