NPIPM:Psychodidae
Authors: Ashley Mueller, Buyung Hadi
Flies are one of the most recognizable pests in the home. While they can be a nuisance, some species are a cause for health concern. These medically important flies are capable of transmitting bacteria and other disease-producing organisms that can affect the human digestive system.
Flies undergo four developmental stages: egg, larval, pupal, and adult. Flies are attracted to decaying organic materials. Places in the home where they are likely to reside are near room-temperature ripened produce and seldom-used drains and sinks. Adult flies are primarily active during the day, so they are often noticed. Preventing and managing flies indoors requires proper food storage and good sanitation practices in the kitchen and regular cleaning of areas that could be optimal breeding sites.
Identification
Drain flies (various species) are very small (about 1/6 inch long), moth-like flies with furry bodies. Depending on the species, these flies can range in color from dark gray and black to very colorful metallic bodies. The wings of the drain fly appear to be too big for its body. They are not strong fliers.
Habitat
Drain flies can live indoors and outdoors. Drain flies lay eggs in areas with gelatinous rotting material, such as in and around garbage cans, rain barrels, sink and floors drains, toilet bowls, and toilet tanks. Indoors, adults can be found resting on ceilings and walls.
In the summer, drain flies can breed outside. Adults are able to make their way into the home through windows, doors, and basement cracks.
Life Cycle and Seasonal History
Often times, drain flies are noticed following a homeowner’s vacation or extended travel. They develop in standing water or thin surface films. When normal household activity starts again, they usually disappear.
Even at room temperature, the drain fly life cycle is very short. Females lay 10-200 eggs in or on moist organic matter. Within two days, the eggs hatch and the larvae feed on the decaying organic matter. Larvae mature in nine to 15 days, then they pupate in or on the sludge surface. Adults emerge in one to two days.
Human Interaction and Urban Impact
Drain flies are not a medically or economically important pest. Drain flies do not bite; they are harmless. However, in the occasional instance they are present in large numbers, they can be a nuisance.
Prevention and Management Approaches
In most cases, the presence of drain flies in the home is short-lived. A fly swatter may be a useful tool in ridding the home of adults. To prevent adults from entering the home, seal entry points such as cracks in the foundation and pipes and around windows and doors.
A simple way to determine the presence of drain flies in the home is to cover the inside of an empty translucent container, such as a butter tub, with a thin layer of petroleum jelly. Place the container upside-down over the drain, and leave it in place overnight or for a few days. Check the container daily. If drain flies are present, emerging adults will be trapped in the petroleum jelly.
Preventing and eliminating breeding sites will reduce the risk of drain fly outbreaks. Routinely inspect pipes and clean toilets and drains to reduce potential breeding sites. Pouring hot water down drains is a short-term control option. Insecticides should never be poured in drains.
Harsh chemicals are not necessary to manage these flies. If a breeding site is identified, DF 5000 gel, a selective bacteria complex, can be applied to the site. This product is not sold to the customer market; it is only available to pest control operators and hospital, restaurant, and food service personnel. A product available to homeowners is Invade Bio Drain by Rockwell Labs. It has a similar mode of action to DF 5000 gel. Always use precaution and follow the label carefully before using any insecticide. Insecticides have a certain amount of toxicity to mammals; children and pets are especially at risk.
Other Online Resources
North Carolina State University
For information regarding labels of chemical control options, please visit NPIC MAPL
