Cluster Flies

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Top-Down Diagram of a cluster fly

What are cluster flies?

They look like flies. About 7 mm long. Distinct lines or stripes behind the head. Short golden-coloured hairs on the thorax. Irregular light and dark gray areas on the abdomen. They’re noticeably slow moving. Cluster flies are also known as attic flies.

Cluster flies pose no health risk to humans. They don’t lay eggs in human food. But, are parasitic on earthworms. Females lay eggs near worm burrows and the larvae infest the worms. For us though, cluster flies become annoying. Around late summer of all flies look for places to hibernate and with enter your home.

Where are they typically found?

Cluster flies are very difficult to get rid of; They exist in large numbers and infestation can quickly get out of control. Flies get into attics and are attracted to inaccessible spaces such as roof and wall cavities. They can also be spotted on windows of rarely used rooms. Window screens have little effectiveness to prevent cluster flies. They can crawl through small holes and cracks. Cluster flies will always look to move towards windows.