Key Features of Cluster Flies
Cluster Flies have a dark grey colouring and measure approximately 8mm long. They have overlapping wings with yellowish hairs on their back.
Biology
The female Cluster Fly will lay their eggs one at a time in cracks in the soil. The larvae will then begin to emerge within three days begin to seek out their food source, earthworms almost immediately.
After burrowing into the earthworm, the larvae will feed for three weeks before then beginning to pupate. The adult Cluster Fly emerges from its pupa after almost 2 weeks. There are 3 to 4 generations of adult flies per year and their primary source of food are flowers.
In autumn they will look for somewhere to hibernate and can often be found congregating in large numbers in upper rooms or the roof spaces of houses.
Because the larvae of one species is parasitic upon certain earthworms, it is far more common in rural areas.
A mass of cluster flies produce a characteristic smell, is sluggish in flight and is a nuisance when trapped within a house.
