The presence of Filter Flies, or Drain Flies, in bathrooms is not uncommon, but that does not make it any more welcome.
Fuzzy, black Filter Flies are often seen sitting on bathroom stall doors and the surrounding walls. Many a human has swatted at one in an attempt to keep it from landing on them while exposed and in a vulnerable position. Toilets and sinks are not the only place one finds this type of fly. In nature, it is often seen near stinky ponds and other wet areas where decay occurs. Most people, however, associate this type of Moth Fly with sewage, waste, and garbage.
Because this small fly sports fuzz on its wings, it resembles a moth. The Filter Fly is black with a hairy fringe around its rounded wings. It has two black dots on the upper part of each wing. A faintly checkered border around the wings edges may show small white spots. The gray-black thorax is very hairy, as is its body (the abdomen). Antennae are white tipped and segmented. Two of its six black legs are usually out in front of the fly when resting. Look for a thin, white ring around the legs.
The dark, wormy larvae, or maggots, of the Filter Fly feed on decaying matter. That can be of plant origin in near the edge of a stagnant pond, or it can be garbage. This species is not known to spread disease, but the knowledge of what kind of matter the adult lands on is often enough to instill a strong dislike of its company.
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