Cluster Flies

The cluster fly is approximately 10mm in length, slightly larger than the common house fly. The thorax is greyish in colour and covered in golden hairs.

Where do they live?

Adult flies become numerous during the latter days of September to mid-October. As cold weather progresses, adults seek protected places to spend the winter. In many cases, this is within walls, attics, storage rooms and basements of houses.

Fly screens offer no protection since these flies prefer to crawl in through small openings elsewhere around the building.

For this reason they are extremely difficult to keep out of houses. Isolated houses in the country are especially prone to invasion, since they offer the only warm shelter for miles around.

What do they eat?

The female lays eggs in the soil near the burrows of earthworms. The tiny maggots that hatch from the eggs seek out earthworms to feed on. When full grown, the maggot leaves the body of the host and enters the soil. There are about four generations a year.

Pest status:

Can be a nuisance when large numbers of flies enter inhabited properties in the autumn.

Control Measures:

Insecticidal Control - Adults are sluggish enough in the winter to be picked up with a vacuum cleaner or can be killed with an aerosol spray. Complete control of cluster flies using this method is almost impossible since the over wintering adults are concealed in walls, attics, etc.

Professional Help - Wirral Borough Council does not provide a service. However, commercial Pest Control Companies are listed in the Yellow Pages and Thompson's Local Directory. 

When using pesticides always follow the instructions on the label!