These are dark greyish flies about 8mm long with yellowish hairs on the back and with overlapping wings. In autumn they congregate in large numbers in upper rooms or roof spaces of houses to hibernate. A mass of cluster flies has a characteristic smell. They are sluggish in flight and are a nuisance in the house. The larvae of one species are parasitic upon certain earthworms, so this species is more common in rural areas.

Remedy:

A combination of physical and chemical control methods can be used to for Cluster Fly Pest Control. Silicone or other suitable exterior sealing compound can help block their entry points, but once the flies have entered a loft or attic space, control can be carried out with a range of insecticides and formulations. Most pyrethrum and pyrethoid based space sprays can be used to quickly kill exposed flies, but it is recommended that a pest control professional is consulted for the best solution.