Fly IdentificationThe Cluster fly is 6–10mm in length. It has a dark grey–olive thorax clothed with crinkled golden–brown hairs. Wings overlap when at rest. Sluggish in flight.
DescriptionCluster flies are commonly found in quiet, undisturbed parts of your home, such as attics and wall voids. They require warm places to hibernate over winter. You may see a large group of cluster flies around a window, as they are attracted to the light on sunny winter days. Eggs laid in soil in late summer or early autumn. Larva develop in earthworms – feeding on their host for several days. Then they molt and pupate in the soil. Development time from egg to adult is about 27 to 39 days.