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The Common House Fly…maybe not so common?

Identification

The common house fly is medium sized (about ¼ inch long) and is found all over the world. The adult has the fourth wing vein sharply angled and four length-wise dark stripes on the top of the thorax. Its face has two velvety stripes which are silver above and gold below. The female fly has a much wider space between the eyes than the male.

Biology & Behavior

Each adult female begins laying eggs a few days after hatching, laying a total of five to six batches of 75 to 100 small white oval eggs. In warm weather, eggs hatch in 12 to 24 hours into cream-colored larvae, which burrow into the food material on top of which they hatched. These larvae develop into the next stage of development known as the pupate within 4 to 7 days. The mature larva shrinks forming a case about ¼ inch long within which the pupa develops. When fully formed, the adult fly breaks open the end of this case and emerges. Within a few hours of emerging, the male is ready to mate. The hardened larval skin, which is left behind and relatively unchanged in appearance is often used for detection purposes.

Reproduction is so quick in the summer months, that two or more generations of house flies may be completed in a month. Normally the population builds up and is greatest in early fall months. However, in some areas, populations develop indoors throughout the winter.

House fly eggs are laid in almost any warm moist material which will furnish suitable food for the growing larvae. Animal or human excrement, garbage, decaying vegetable material and ground contaminated with organic materials are suitable sites. Although they are attracted to a wide variety of food materials, house flies have mouthparts which enable them to ingest only liquid materials. Solid materials are liquefied by means of regurgitated saliva. This liquefied food is then drawn up by the mouthparts and passed onto the digestive tract.

During the daylight hours, house flies will rest on floors, walls and ceilings indoors. Outdoors they will rest on plants, on the ground, on fence wires, garbage cans and other similar surfaces. At night, they will rest principally on ceilings, electric wires and dangling light cords indoors.  In almost all situations, house flies prefer corners and edges or thin objects such as wires and strings. Night resting places are usually near daytime sources of food and are usually 5 to 15 feet off the ground.

Inspection

Within a home or other facility, common areas of inspection include: trash cans, dirty diapers, and rotting foods; classic breading areas for inspecting house fly activity.  Outside, house flies may be found feeding and breeding in fresh manure, rotting fruits and vegetables, garbage, damp garbage, and decaying organic materials located around the structure.

As a rule of thumb, when you find house flies inside, it is because they are coming in from outside of the structure.  Carefully check cracks around windows, doors and vents as possible entry points. It is crucial to find out where the breeding sources are located and how they are entering the building. Rural areas where farms are present may be more problematic given the higher number of breeding sites compared to an urban setting. In residential areas, pet manure, which is not picked up regularly, can be a breeding source for house flies.

House Flies and Disease…this is important!

House flies are recognized as carriers of easily communicable diseases. Flies collect pathogens on their legs and mouths when females lay eggs on decomposing organic matter such as feces, garbage and animal corpses. House flies carry diseases on their legs and the small hairs that cover their bodies. It takes only a matter of seconds for them to transfer these pathogens to food or touched surfaces. Mature house flies also use saliva to liquefy solid food before feeding on it. During this process, they transfer the pathogens first collected by landing on decomposing matter or garbage.  Diseases carried by house flies include typhoid, cholera and dysentery. Other diseases carried by house flies include salmonella, anthrax and tuberculosis. House flies have also been known to transmit the eggs of parasitic worms.

What can you do?  Exclusion and Sanitation

Sanitation is the first measure of defense, even though there are various traps and sprays that are used to kill flies (best left to your pest professional), it is necessary to eliminate the source to eliminate them.

Whenever possible, food and materials on which the flies can lay their eggs must be removed or destroyed, which will isolate the egg-laying adult.

Killing adult flies will reduce infestation, but elimination of breeding areas is necessary for good House Fly control management.

Garbage cans and dumpsters should have tight-fitting lids and be cleaned regularly.

Drainage will often aid control, getting rid of extra moisture.

Openings of buildings should be tightly screened with screen

Next Steps

EcoChoice Termite and Pest Control can offer you more in-depth strategies to rid you of the annoyance of the common house fly.  While removing the underlying source of breeding is the number one priority, there are a multitude of insecticides, aerosols, fogging materials and traps (some with lures) that can be carefully applied to eliminate the problem.