Larvae feed on the decaying organic matter, microorganisms, algae and sediment in the media. Larvae mature in 9 to 15 days and are considered valuable organisms along with the organic film in purifying sewage water. Larvae live in the organic film, breathing through tubes and feeding on sediment, decaying vegetation, along with microscopic plants and animals in filters at sewage plants. Pupae occur in or on the surface of the breeding media and, after 20 to 40 hours, new adults emerge. The life cycle can be completed in one to three weeks.
Adults live about two weeks, with old ones dying and new ones emerging.
They feed on flower nectar and polluted water. During the day, adults rest in shaded areas or on walls near plumbing fixtures and on the sides of showers and tubs. Most activity occurs during the evening when these flies are seen hovering about drains and sinks. They may breed in large numbers at sewage filter plants and then may be carried by prevailing wind to nearby homes up to a mile away. Adults are small enough to pass through ordinary window screening.