We are most concerned with these flies when they appear in our houses creating annoyance. Moth flies are also called filter flies, drain flies and sewage gnats. The larvae breed in moist organic matter and feed principally on algae. The muck of gelatinous material that accumulates on the sides of drains and overflow pipes in houses may provide suitable breeding sites.
Some species are able to survive hot water and soap.
Where they are a problem, the adults may be seen resting on walls in kitchens, bathrooms and basements. Usually only a few are present at any on time, some die off, and others emerge, but occasionally, they may occur in large numbers. They are not strong fliers and are often seen crawling over the walls or other surfaces. When they do fly, they cover only a few feet at a time and fly in a jerky line. The adults may be attracted to lights.