Order: Diptera

Family: Psychodidae

Drain flies are also referred to as "moth flies", "filter flies", and "sewage flies". These names represent the different place or situations typical to their breeding sites. Drain flies are found throughout the world.

Description: Drain fly adults are 1/16-1/4inch long. They appear to be delicate and fuzzy. Their color varies from yellow to brown to gray to black depending on the species. However, our local Drain fly population is mostly grayish in color.

Biology: Female drain flies lay 30-100 eggs at a time in the gelatinous film (scum) of drain pipes and filter stones of sewage treatment plants. While the eggs are deposited on the surface of this film, the larva and pupa live in the film with breathing tubes projected through the film. The developmental time from egg to adult is 7-28 days.

Habits: Adult drain flies are weak fliers and are more typically seen crawling on walls or other vertical surfaces. When they are seen flying, it is only for a short distance and is characterized with short, jerky movements. They are active in the evening and can be observed hovering over drain openings.