Life Cycle: The adult fly lays its eggs in the soil. After hatching in 3-4 days the larvae penetrate earthworms on which they feed.
Behaviour: They derive their name from their habit of entering a house from August to September and “clustering” over winter. They gather in wall voids, attics, window frame voids and other secluded areas to rest over winter.
Signs of Infestation: With the arrival of Spring, Cluster flies emerge by the hundreds on warm days to bask in the sun on outside walls or on the inside of windows.