Subfamily Psychodinae - Moth Flies

Drain Flies, Sewage Flies, Filth Flies

1.5-4 mm(1)

worldwide

Adults often found around sewage installations, in public washrooms, and bathrooms in homes, and are attracted to light; larvae live in organic sludge that forms on inner surfaces of drains and sewage pipes; pupae occur on the surface of the organic film that the larvae have been living in

Larvae feed on algae, fungi and bacteria in sewage and organic sludge; adults feed in polluted water and on flower nectar

In the home, females lay irregular masses of 30-200 eggs in the organic gelatinous film lining drains, particularly in bathtubs and showers; eggs hatch 32-48 hours after being laid, when ambient temperatures are 70ºF (about 20ºC), and larvae pupate 9-15 days later; pupa stage lasts 20-40 hours; development time from egg to adult is 7-28 days, depending on temperature and food availability; adults live for about two weeks

Larvae play an important role in purifying sewage in industrial sewage treatment plants. Adults are very weak fliers, covering only a few feet at a time in short erratic flights. Outside, they can be blown considerable distances by the wind.

The Subfamily Trichomyiinae has some very similar species.

Examples: Quatiella -- and -- Trichomyia

Fact sheet by G.E. Ridge