The housefly (also house fly, house-fly or common housefly), Musca domestica, is a fly of the suborder Cyclorrhapha. It is the most common of all domestic flies, accounting for about 91% of all flies in human habitations, and indeed one of the most widely distributed insects, found all over the world. It is considered a pest that can carry serious diseases.
Their thorax is blue or sometimes even black, with four longitudinal dark lines on the back. The whole body is covered with hair-like projections. The females are slightly larger than the males, and have a much larger space between their red compound eyes. The mass of pupae can range from about 8 to 20 mg under different conditions.
Like other Diptera (meaning "two-winged"), houseflies have only one pair of wings; the hind pair is reduced to small halteres that aid in flight stability. Characteristically, the media vein (M1+2 or fourth long vein of the wing) shows a sharp upward bend.
Species that appear similar to the housefly include:
- The lesser house fly, Fannia canicularis, is somewhat smaller, more slender, and the media vein is straight.
- The stable fly, Stomoxys calcitrans, has piercing mouthparts and the media vein is only slightly curved.
Each female fly can lay approximately 500 eggs in a lifetime, in several batches of about 75 to 150. The eggs are white and are about 1.2 mm in length. Within a day, larvae (maggots) hatch from the eggs; they live and feed on (usually dead and decaying) organic material, such as garbage, carrion or feces. They are pale-whitish, 3–9 mm long, thinner at the mouth end, and have no legs. Their life cycle ranges from 14 hours to 36 hours. At the end of their fourth instar, the maggots crawl to a dry, cool place and transform into pupae, coloured reddish or brown and about 8 mm long. The adult flies then emerge from the pupae. (This whole cycle is known as complete metamorphosis.) The adults live from two weeks to a month in the wild, or longer in benign laboratory conditions. Having emerged from the pupae, the flies cease to grow; small flies are not necessarily young flies, but are instead the result of getting insufficient food during the larval stage.
Some 36 hours after having emerged from the pupa, the female is receptive for mating. The male mounts her from behind to inject sperm. Copulation takes a few seconds to a couple of minutes. Normally, the female mates only once, storing the sperm to use it repeatedly for laying several sets of eggs.
The flies depend on warm temperatures; generally, the warmer the temperature, the faster the flies will develop.