Drain flies (Psychoda alternata Say), also known as moth flies, are part of the insect family. Drain flies upon close inspection have a fuzzy, hair-like covered body. Their antenna, broken into 13 segments, are covered in a fine hair which acts as mini-tongues for the insect as it forages for food. Similar to the moth, their wings are held aloft from their body creating a tent-like roof. Their large wings and small body make the drain fly a poor flier; most of their flight paths are short and chaotic, covering a few feet at best. These tiny pests at their full grown size, are approximately 1/5 to 1/6 inches long.
Their small size enables them to easily fit though screened window coverings which is a nuisance to house painters. Drain flies are attracted to damp sources, so a home owner attempting to properly vent a painted room may return to find these small pests trapped in their new paint. A tip to avoid this problem is to cover the open windows with a layer of damp cheese cloth. The cheese cloth has a much smaller weave than the typical window screen and the damp fibers will not allow the drain fly to pass through.
Drain flies do not bite as most insects do, but can pose a serious health risk to humans. They are naturally attracted to damp places which can lead them to land and breed in sewers, landfills, grease traps, and clogged drains. In some cases, drain flies are carried by the wind from sewage treatment plants and landfills. These unsanitary locations can be breeding grounds for disease. Their small size can cause great problems for those suffering from lung disorders such as bronchial asthma. In some instanced their body segments have been inhaled into human lungs.
The drain fly has an extremely short three week life cycle. The drain fly begins life as brown or cream-colored egg laid in groups of 30-100. Since the drain fly is attracted to a naturally moist environment, the egg masses are commonly laid in shallow standing water found in tree trunks, overflow pipes inside buildings, garbage disposal units, rain barrels, and septic tanks. If the eggs are laid in the optimal climate of 70 degrees Fahrenheit, they may hatch in as little as 32-48 hours.
From the egg state, the drain fly moves to the larvae stage. Where the larvae is born depends on its survival. The larvae needs to feed on damp, decaying organic matter, so should their source of nourishment dry up suddenly, for instance the sun drying out a patch of sidewalk algae, halted development and most likely death will occur.
At the larvae stage, the drain fly measures about 3/8 inch long. It appears to be gray and has a wormlike shape for at this stage the drain fly lacks the legs and wings that still have to develop. Within 9-15 days, the larvae progresses to the pupae stage. The pupae stage is the shortest life span of the drain fly, lasting from 20-40 hours. At that time, barely after the passage of 4 days, a fully developed adult drain fly appears. Within the first few hours of adult life, the adult drain fly is able to reproduce and the life cycle begins anew. By day, the adult drain fly prefers to rest in shaded areas corners of the wall, in the damp soil of indoor house plants, and in showers or sinks near the drain opening.
In regards to eradicating drain flies from your residence, an ounce of prevention is worth a pound of cure. Many home owners will arrive home from an extended vacation to find that their residence is infested with drain flies. Most often the source of the infestation is due to stagnant water found in pipes. When normal activity levels return to the household and water begins to re-circulate through the pipes, any eggs or immature drain flies will be washed away. Adults however are able to fly out of the drains and will avoid death. Once the drains are operating, if drain flies are still present, the source of their breeding must be discovered. The chemical products that exist on the market will help kill any adult flies and eggs that are living, but for a long-term solution, the source of dampness must be eliminated if any permanent solution is to occur.
Cleaning the pipes with a long handled pipe brush or by using a commercial grade product will assist in preventing additional infestations. If there is a garbage disposal attached to the kitchen sink, it should be run and flushed with hot water on a daily basis. Garbage should be taken out daily as even the smallest bit of over-night decay may become a source of breeding. If plants are kept indoors, the overflow water in the water pans should be emptied no more than 3 hours later.
Carefully inspect the outside of the residence. Broken, leaky septic tanks and sewer lines are a common culprit. A licensed, professional plumber or a member of the town’s sanitation crew should be contacted immediately to repair the damage. If freestanding water is resting against the house, locate the source and redirect the overflow. That may involve digging a trench, extending a gutter, or capping off an open faucet. If an air conditioning unit is creating condensation pools, drain flies born and bred in that location have direct access to the ventilation system throughout the entire structure.
- Drain flies are small gnats that have an average life span of 3 weeks.
- Within the first five hours of its adult life, the drain fly is capable of reproducing.
- Drain flies can be disease carriers and act as triggers for asthmatics.
- The best way to prevent drain flies is to remove any source of dampness where they are likely to breed.
- While the average infestation can be remedied by flushing stagnant waters out of drains, there are products on the commercial market which exist to assist in the eradication and prevention of drain flies