
As temperatures begin to drop, you may notice an increase in flies gathering around your windows, walls, or attic. These unwelcome visitors could be cluster flies, a common fall pest that seeks shelter inside homes as colder weather approaches.
What Are Cluster Flies?
Cluster flies are slightly larger than common houseflies and typically have dark gray bodies with small golden hairs. Unlike houseflies, they aren’t attracted to garbage or food. Instead, they spend much of their lives outdoors, where their larvae develop as parasites of earthworms.

Why Do They Enter Homes?
During the fall, cluster flies search for warm, protected places to spend the winter. They often enter through small cracks and gaps around windows, siding, vents, and rooflines. Once inside, they gather in attics, wall voids, and other undisturbed areas. On warmer winter days, they may become active and appear around sunny windows.
How Can You Prevent Cluster Flies?
The best way to keep cluster flies out is to take preventive measures before they settle in.
- Seal cracks and gaps around windows, doors, and siding.
- Repair damaged window screens and weatherstripping.
- Check attic vents and other potential entry points.
- Vacuum up any flies that make their way indoors.

Let Clegg’s Pest Control Help!
While cluster flies don’t typically cause structural damage or reproduce inside homes, large numbers can quickly become a nuisance. If you’re noticing cluster flies around your home, Clegg’s Pest Control can help identify potential entry points and recommend solutions to keep unwanted pests outside where they belong.
Contact Clegg’s Pest Control today to help protect your home from seasonal pests!