Flies have well-developed front wings, but the hind wings are simply small knobbed structures. Adult flies are active during the day, sometimes at dawn or dusk. The larva is the primary feeding stage, while the adult stage is dedicated to dispersal and laying eggs. Larvae are usually buried in the food substance, with only their posterior end exposed for breathing. Some adults, such as moth flies, remain close to the larval development site; others, such as house flies, move far from that site.
Food eaten by fly larvae includes plant and animal material—some fresh, some partially decayed, and some rotting. Food location and selection is conducted by the female; she selects material that will be suitable for the larval stage. Females are usually attracted to odors, because the gases indicate a suitable larval food source. Fruit fly females will return to the site of their larval development to lay eggs for the next generation. Blow flies and phorid flies can locate and deposit eggs on the carcass of a dead rat or mouse deep in a wall void.
The larvae or maggot is the primary feeding stage, and egg—to-adult development usually takes about 10 days. A fly larva develops into an adult in a protective case called a puparium. The adult emerges from the puparium in about 10 days by pushing the end of the puparium open. Adults usually do not feed or they take only liquids, and they do not live long. For example, an adult house fly or fruit fly lives about 30 days; an adult midge may live only a few hours or days. The female mosquito must take a blood meal to live and develop her eggs.
Fly control in and around restaurants and kitchens begins with inspection and identifying of larval breeding sites. The breeding sites for most fly pests are outside, but some may be inside. House flies breed primarily outdoors in decaying garbage; moth flies usually breed in indoor decaying organic material. Mosquitoes breed in standing water that may occur in discarded containers or small pools. Female mosquitoes are capable of flying a long distance to find a blood meal. The Asian tiger mosquito frequently breeds in small amounts of water around buildings. This species is active in late spring and throughout the summer; sometimes there is a second peak of activity in the fall.