Cluster Flies

The Cluster Fly is often mistaken for the common house fly but they are more sluggish and often appear to fly very slowly. They can overwinter in vast numbers in lofts, cellars and dark voids. These flies are of no particular harm but can be alarming because of their great numbers. Generally noticed on the first warm days of spring when they congregate on the inside of windows. Frequently found in window frames, particularly sash windows. Interesting life cycle - lay eggs in damp earth and resulting larvae migrate into the bodies of earthworms where they develop into maggots which then bore out of the worm to pupate. Easily controlled with spray, fumer or electronic device.

Cluster Flies: Description & Life Cycle

The Cluster Fly overwinters in lofts, cellars and voids within the stucture of buildings.

Description:

slightly larger than the house fly
slower flying
non-metalic, dark grey in colour
dark grey abdomen with lighter patches
characteristic golden hairs on body
wings overlap at the tip when at rest

Lifecycle:

adult lays her eggs singly in damp,moist soil or leaf litter
emerging maggot penetrates and enters a living earthworm
feeds on worm for 13 - 22 days
emerges from worm at pupal stage and pupates after 11-14 days
up to four generation over the summer months
hibernates as an adult fly in lofts etc overwinter
crowds on the internal side of windows trying to get outside with the first warm days of spring