Drain flies and other home annoyances

By Stephanie Hughes

OSU Extension Master Gardener Volunteer

At some point, everyone has some small insects invading the home. In my personal quest to identify the small insects invading my own house, I discovered drain flies to be the culprits. They also are called moth flies (Psycloda alternata sp.) and are closely related to insects called sewage gnat psychids (Psychoda cinerea sp.) and filter flies (Telmato scopus albipunctatrus [will.]).

These mysterious little flies can be a nuisance in homes, as well as sewage treatment plants. Adults can congregate at windows (they can pass through screens), at lamps at night, get into food, and are attracted to showers, bathtubs, sinks and drains. They get into the eyes, ears and nose and can transmit diseases. Adults are active at night and rest during the day.

Adults are 1/5- to 1/2-inch long, with fuzzy dark or grayish bodies covered with hairs. They have long segmented antennae with whorls of hair, large wings that are held over the body at rest, making them look moth-like. They are weak fliers and travel in short jerky patterns. They lay from 10 to 200 eggs, in masses, and larvae are 3/8-inch long, gray worm-like, with the ends darkened. Eggs can hatch in 36 to 48 hours at a temperature of 70 degrees, and larvae proceed to feed. The larvae mature in nine to 15 days, pupates in 20 to 40 hours, and adults emerge. In one to three weeks the reproduction cycle begins again. The adults live two weeks, feeding on flower nectar and polluted water.

The drain fly reproduces in polluted, shallow water or moist organic solids (like what’s in the drains of your home.) Eggs, larvae and pupae are found in muck, slime or gelatinous film on the sides of drains and overflow pipes in homes, sewage plants, septic systems and moist compost. They also can be found in dirty garbage containers, rain barrels, even tree holes. If moth flies are present, clean drains and traps using DF-5000 Drain Fly Eliminator, a non-acid, non-caustic bacterial that biodegrades organic matter. DF-5000 Ccl (not an insecticide) rapidly attacks and destroys organic matter. It clings to pipes and traps. Pour around the drain to coat, treating five days in a row, and monthly thereafter. This treatment is harmless to plastic, metal and glass. Read and follow all instructions and labels.

Pipes also can be scrubbed with a long-handled brush, and drains should be snaked, flushing with boiling water and bleach to finish the cleaning. Caustics may be used, though not as effective, and never follow with bleach. Again, read and follow all labels and directions.

Clean garbage containers, lint in washers and dryer areas, even water under houseplants. Clean outside around air conditioners, bird baths, shallow pools and any sewage areas.

For more details: http://go.osu.edu/drainfly .