House flies are not the neatest of insects. They visit such places as dumps, sewers, and garbage heaps. They feed on fecal matter, discharges from wounds and sores, sputum, and all sorts of moist decaying matter such as spoiled fish, eggs and meat.
House flies are strongly suspected of transmitting at least 65 diseases to humans, including typhoid fever, dysentery, cholera, poliomyelitis, yaws, anthrax, tularemia, leprosy and tuberculosis. Flies regurgitate and excrete wherever they come to rest and thereby mechanically transmit disease organisms.
House flies can be easily identified by the four dark, longitudinal stripes on top of the thorax, or middle body region. They vary in length from l/8-l/4 of an inch. Their mouth parts are adapted for sponging up liquids; they cannot bite. These flies can only ingest liquid food. They feed on attractive solid food by regurgitating saliva on it. The saliva liquifies the solid material which is then sponged up with the proboscis. They require water since they are continually salivating and voiding liquids. Fly specks seen on many surfaces visited by house flies are the excreted wastes.
Photo by Jim Kalisch University of Nebraska Department of Entomology
The eggs are deposited in decaying matter such as grass clippings, garbage, human and animal excrement. Horse manure is the preferred breeding medium. About l00-l50 eggs are deposited by each female on appropriate food. Eggs may hatch in 7 l/2 hours when temperatures are high (about 99× F), or it may take two days if the temperature is only 59×F. Eggs hatch into worm-like creatures called maggots (Fig. 1b). Maggots lack definite heads, eyes, antennae or legs. Their bodies are pointed at their front end and gradually widen at the rear.
They feed on the material in which they find themselves. There are three larval molts. Mature larvae stop feeding and burrow for protection in drier surrounding areas, where they pupate. The pupa is a chestnut brown, oval object within which the larva changes into an adult house fly. Adults mate within one to two days after emerging from their pupal cases. The life cycle, from egg to adult, may take as little as one week, but normally requires three weeks for completion. House flies normally live about 2 l/2 weeks during the summer, but they can, at lower temperatures, survive up to three months. Some overwinter outdoors in protected locations, or in crevices in buildings. Flies normally stay within l/2-2 miles of their point of origin, but have been known to travel as far as 20 miles to find food and ovipositional sites.
Partially reproduced from the Penn State College of Agricultural Sciences House Flies Fact Sheet
Authored by: Steve Jacobs, Sr. Extension Associate Revised August 2007
For the Complete Fact Sheet please go to this link: http://ento.psu.edu/extension/factsheets/house-flies