Iron Mountain
906-774-1071
© 2025 Lakeshore Exterminating Company
Iron Mountain
906-774-1071
Remove Cluster Flies
The cluster flies are the genus Pollenia in the blowfly family
Calliphoridae. Unlike more familiar blow flies, such as the
bluebottle genus Phormia, they do not present a health
hazard because they do not lay eggs in human food. They
are strictly parasitic on earthworms; the females lay their
eggs near earthworm burrows, and the larvae then infest
the worms. However, the flies are a nuisance; when the
adults emerge in the late summer or autumn, they enter
houses to hibernate, often in large numbers; they are
difficult to eradicate because they reside inaccessible
spaces such as roof and wall cavities. They are often seen
on windows of little-used rooms. They are also sometimes
known as attic flies.
How can you identify cluster flies?
The typical cluster fly Pollenia rudis is about 7 mm long and can be recognized by
distinct lines or stripes behind the head, short golden-colored hairs on the thorax, and
irregular light and dark gray areas on the abdomen. Cluster flies are typically slow-
moving.