Pest description and damage Resemble houseflies but with a hint of gold color behind the head. They enter houses in the fall and may congregate on the ceiling or at windows. Immature cluster flies are earthworm parasites. They do not reproduce inside structures and, if not controlled, will die on their own.
Control is similar to that of houseflies. Seal window and door edges to prevent fly entry. Keep window screens in good repair. Aerosol space sprays may be effective, but will only affect the flies currently in the treated area. An outward-facing fan placed near an open window or door will create a positive air current and reduce the likelihood that flies will enter at that location.