Cluster Flies: Why They’re Invading Your Home This Fall

Dozens of cluster flies gathered on the white siding and window frame of a home on a sunny autumn day
Dozens of cluster flies gathered on the white siding and window frame of a home on a sunny autumn day

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.

Close-up of a cluster fly showing its dark gray body, small golden hairs and reddish-brown eyes

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.
Infographic titled How to Prevent Cluster Flies showing four steps: seal cracks and gaps around windows, doors and siding; repair damaged window screens and weatherstripping; check attic vents and other potential entry points; and 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!

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