House flies receive their common name from being the most common fly that is found infesting the inside and outside of homes, especially in the rural areas. House flies are considered a nuisance pest and moreover, they have potential to be a vector of a variety of diseases. It is known that they have been found to harbor or carry over 100 different pathogenic organisms. It is commonly found all over the world, including the United States.
House fly adults are about 4 mm – 7.5 mm long. The color of their bodies is a dull gray color and their abdomens are usually paler than the rest of the body. They can be identified by two signifying stripes on their faces. A silver colored stripe, which is located above a gold colored stripe. They also have 4 identifiable stripes on their thorax that are black in color. Females and males have slight physical differences such as size and eyes. Female house flies are generally larger than male house flies. Also, the eyes of female house flies are more widely separated than male house flies.
The larval stage, or more commonly known as the maggot stage, is what most people usually find contaminating the food in their house. Mature house fly larvae are about 7 mm to 10 mm long. Fly larvae are generally legless and eyeless. They also taper towards either end at the head and rear segment. The heads of house fly larvae are differentiated from the rear segment by two hook-like appendages. They have a pale, creamy color but look almost oily or greasy.
Eggs of house flies are oval in shape and about 1 mm long. They are white in color and hard to find with the naked eye when separated from the cluster, however, most female house flies will lay her eggs in clusters.
There are similar groups or species of flies that maybe misidentified as house flies. Such species are flesh flies, stable flies, horse flies and cluster flies.
Although the lifespan of a house fly is very short, they reproduce at an alarming rate. An adult female house fly will usually lay her eggs in clusters of 20 – 50 eggs. There are several clusters in a “batch” which means that in one batch, a female will lay about 75 – 150 eggs. Moreover, the female house fly will lay several “batches” in her lifetime which amounts to a total of about 350 – 900 eggs in one lifetime. Female house flies lay their eggs on moist materials and only after about 8 – 20 hours, the eggs hatch and develop into larvae. Larvae go through 3 instars and fully develop after 3 – 7 days. Although larvae develop in moist areas, they will move up to 150 feet to find a cool, dry place to pupate. Initially, pupa looks yellowish in color and as the pupa develops, they will change to a black color. Pupation takes anywhere between 3 days to 4 weeks. After the fly emerges from the pupa, they spend about an hour to harden their wings and the body. Adult flies live about 15-25 days and there can be up to 10-12 generations in just one season.
House flies are attracted to a wide variety of materials including excrement to human foods. They are limited to just liquids because of the way their mouthparts are built, however, through regurgitation, they are able to liquefy most solid foods. Even though house flies are able to migrate up to 20 miles, most will stay within 1 – 2 miles from their initial release point if there is an adequate food source. At night, house flies rest on surfaces that are usually close to their daytime food source.
A house fly excretes and regurgitates almost every time they come to a rest. This habit, in conjunction with their physical attributes like many body bristles and the sticky base on the claws of their legs, make house flies very susceptible and adaptive to disease organisms. They have been known to be vectors to over 100 different kinds of disease pathogens. Most of the pathogens are associated with filth and most of them are harmful to people. Some of these pathogens are the cause of several different diseases like diarrhea, cholera, tuberculosis, polio, salmonellosis, parasitic worms and etc. They spread pathogens via their feces excretes, regurgitated vomit and anything that is contaminated on the external parts of their bodies.
There are multiple steps that are required in getting rid of house flies which includes inspection and identification, sanitation, and mechanical and chemical control. Inspection and identification involves locating the initial release site or breeding site and making sure that they are house flies. Because flies rest nearby their food source during the night, it may be easier to locate the breeding site during the evening or night time. Sanitation is crucial for house fly control because most breeding sites are located on rotting food, fermented materials, or other areas where trash is readily available as a food source. Sanitation involves removing or eliminating all potential areas of development like regularly emptying and cleaning trash bins. When sanitation is regularly maintained, mechanical and chemical control is the most effective. Mechanical control involves making sure that all entry points are blocked off. This may involve checking to see if window screens and doors are tightly fitted and secure, all cracks, crevices, or holes on the exterior walls are closed off, and making sure that all vents are secure and screened. Also, mechanical control will involve using such tools like insect light traps, insect glue boards or glue ribbons and etc. To kill house flies with chemicals involve using an appropriately labeled insecticide. There are fly baits available that will kill flies upon ingestion. There are also contact kill liquid insecticides that are available. Typically, microencapsulated formulas or wettable powder insecticides work the best on flying insects like house flies. Also, ULV insecticides, which stands for Ultra Low Volume”, can be applied through foggers or misters and may often times be required as an initial treatment for heavy infestations.