Cluster Fly

Cluster flies are the most common fly found in properties during the cool months. Cluster flies are known to enter residential, recreational/cottage and commercial properties in “clusters” during the late summer/early fall months in search of a protected place to overwinter in secluded areas such as in wall voids, attics, closets and empty rooms usually in upper regions of the premises. They can enter the home through the smallest crevices around door and window frames, but also through any other small unsealed opening. Once inside, while it is cold they are dormant. On very sunny days, even in winter, they may become active and sometimes will be found flying around the premises. They are frequently found at windows because the light from outside attracts them. In the spring, cluster flies leave their overwintering sites to breed.

Because of their unusual developmental habits and the ability to heavily infest a property, cluster flies also are one of the trickiest pests to control. The main areas that cluster flies enter properties are often up high. These include soffits and facia, gable ends, dormers, vents and flashing. They will also enter through cracks and crevices between bricks, stones, siding, around windows and doors or other tiny openings in the structure. Once they are inside a property, cluster flies can cause allergies if in large numbers, attract secondary pests such as larder beetles, provide food for secondary pests, leave stains on walls and draperies and cause an unpleasant odour