Cluster Flies—Pollenia spp.

These insects, sometimes called "attic flies," often become pests in homes. They usually appear in late fall or early winter and again on warm, sunny days in early spring. They buzz around the home and gather in large numbers at windows, often in rooms that are not regularly used.

cluster fly adult
The cluster fly is a little larger than the common housefly and moves sluggishly. It can be recognized by the short, golden colored hairs on its thorax, the part of the body to which the legs and wings are attached. The larvae, or maggots, of cluster flies develop as parasites in the bodies of earthworms.

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Identification and Control Information

[Photos, left to right: Whitney Cranshaw, Colorado State University, Bugwood.org]