Housefly (Musca domestica) on a doughnut—Avril Ramage/© Oxford Scientific Films Ltd.

Common dipteran (Musca domestica), accounting for about 90% 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.

This entry comes from Encyclopædia Britannica Concise.
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