Description and Habits
Humpbacked flies are tiny, 1/64-1/4 inch, nonbiting flies. Usually, they are black, brown or yellowish and have a humpbacked appearance when viewed from their side. They are also known as Phorid or scuttle flies. They get the name scuttle fly from their habit of running about in an active, erratic manner.
There are many different types of humpbacked flies. Some can be serious indoor pests. They are common in many habitats, but are most abundant around moist, decaying, organic matter including plant and animal material. These flies can mechanically transport disease organisms from their breeding locations.
Common breeding sites, where immatures (larvae) develop, can be extremely diverse. These areas include the organic film that can develop in drain pipes, the bottom of trash cans, under kitchen equipment, on aging fruits, in broken sewage pipes, on medical wastes and in potted plants or vases with flowers. Developmental time varies, but the life cycle for most humpbacked flies (from egg to adult) is approximately two to four weeks.
Finding areas where adult humpbacked flies lay their eggs and larvae develop is extremely important. By altering these sites, sanitation can be used for long term control. Cleaning any moist, organic areas, especially drains, with appropriate cleaners and a stiff brush to remove any film should be effective. Also hidden areas under kitchen equipment and sinks where moist, organic debris can accumulate should not be overlooked. If these measures do not help, a plumber may be needed to check for hidden cracks and leaks in plumbing lines around your home.
All food should be refrigerated or covered. Food should not be left out for long periods of time and trash should be kept covered and removed often. To prevent bringing humpbacked flies from a store inspect food items, especially fruits and vegetables before they are brought into your home. If adults are found in your house, they can be removed by using a vacuum.
Generally, chemical control of adult humpbacked flies is not difficult. Most aerosol insecticides labeled for fly control, when used in the targeted areas, will kill the adults. However, the best long term control methods are nonchemical.
Humpedback flies are small and can look like other types of flies. You can have multiple types of flies in your home at one time. Consider that you may have several areas where flies are breeding or different means by which they have been brought into your house. Inspect all moist organic areas that can serve as a common breeding site. Although there may be no overnight solution, with a thorough inspection and sanitation, control can be achieved.
Originally published 12/99