houseflyColoured scanning electron micrograph of a common housefly (Musca domestica). The head is dominated by a pair of large compound eyes, each eye composed of about 4000 image-forming facets called ommatidia. Mouthparts are visible between and beneath the eyes.

Hairs on the head and body act as tactile organs. Houseflies tend to feed on decomposing matter as well as human food, and they may pick up and transmit serious diseases to humans.