Identification and Life Cycle
The three types of filth flies commonly found in homes is the Fruit Fly (Drosophila spp.), Drain Fly (Psychodidae spp.), and Phorid Fly (Phoridae spp.).
The Fruit Fly is small in size, approximately 1/8 – inch long, has large red eyes and a tan thorax. The abdomen is black on the top and gray in color underneath. They can grow from an egg to an adult in just 8-10 days, and their life span can be approximately 2 weeks. Fruit flies can lay up to 500 eggs in thier short lifetime.
The Drain Fly, also known as the Drain Moth, is about 1/8 inch long and is frequently mistaken for gnats and fruit flies. Its body is dark gray and broad, with fuzzy wings lighter in color. Their life cylce can be completed in one to three weeks and the adults can live up to 2 weeks, laying eggs in masses of 30 to 100.
The Phorid Fly, or “humpbacked” fly is very small in size, 1/16 to 1/8 –inches long. It is black to a dullish brown in color, but some are yellowish. Its high arched thorax gives it a humpbacked appearance. Their life span from an egg to an adult can be as short as 14 days, and the female can lay up to 750 eggs in her lifetime.
All flies belong to the insect order, Dipetera, meaning “two-winged”. A filth flies life cycle consist of 4 stages; egg, larva, pupa and adult. Eggs are laid in a variety of decaying or organic matter and hatch into larva (resembling pale maggots), then they pupate. At this time they do not feed, and soon emerge as an adult in 7-14 days.
Habits and Damage
Filth flies are not only a nuisance but can also pick up disease-causing pathogenic organisms that they can pass on to humans such as tapeworm, typhoid, hookworm, salmonella and more. It is organic material, such as garbage, sewage, and decomposing animal and vegetable matter which they feed on and lay their eggs in. This habit makes them scavengers, and because they come in contact with unsanitary conditions, this enables them to contaminate food and surfaces.
Fruit flies can be a problem all year round. They are attracted to sweet or fermented liquids such as liquor, syrup, soda pop, vinegar, but prefer ripening or rotting fruit. They lay their eggs near the surface of fermenting foods or other moist, organic materials. They are commonly found in homes, restaurants and supermarkets.
Drain flies are commonly found indoors clinging to the walls in bathrooms, kitchens and basements. They feed on flower nectar and stagnant polluted water. They lay their eggs and breed in the muck or gelatinous film often accumulated inside drains, sewage disposal fields, moist compost and septic tanks. Indoors, the source of its infestation is generally from sinks, floor drains, and from nearby waste disposal areas.
Phorid flies breed in decaying organic matter (plant or animal), which present a problem in hospitals, homes and food establishments. They prefer sewage, contaminated soil, garbage drains and damp organic material in such places as the soil of potted plants, clogged basement drains, faulty septic systems, garbage receptacles, etc. They are often confused with fruit flies due to their small size and similar “humpbacked” appearance. They are also mistaken for gnats, as the phorid fly can be seen indoors running rapidly across television screens, tables and windows rather than using its wings to fly.
Prevention and Management
The best strategy for controlling filth flies is to follow good sanitation, inspection and exclusion practices. An Integrated Pest Management (IPM) program can help maintain a pest-free environment.
It is important to properly identify the species and alter conditions in and around a home or building that flies are attracted to. By eliminating their breeding sites on which they lay eggs, you can prevent further fly infestations.
The following steps can be taken to help prevent or reduce a potential problem with flies.
- Correct any moisture problems around the structure such as water leaks in roof, walls and plumbing fixtures.
- Tightly seal plastic bags containing garbage before disposing in receptacles or dumpsters.
- Promptly remove manure, rotting mulch, lawn clippings and animal carcasses from the property.
- Empty food garbage receptacles daily and keep trash containers clean.
- Clean up sugary spills, dead insects, and greasy items on counters and floors.
- Repair holes in window screens & make sure that screens & windows close tightly.
- Eliminate shallow, stagnant pools of water that will attract flies and other insects.
- Inspect your potted house plants for excessive soil moisture which can attract flies.