What’s With Those Annoying Cluster Flies?

We have a bunch of flies at our window every time the sun’s out. They just won’t go away! What can we do??

Cluster flies look a lot like a house flies, but they’re far more annoying, sluggish, and larger. If you notice flies at your home or cottage on days when the temperature is rising and the sun is out, chances are you have a cluster fly infestation. They like to stay in secluded parts of houses like attics and wall voids. On sunny days, when their hiding spaces become warm, they’ll move toward light. This is why you see them “clustering” around windows and sunny areas, often leaving stains on walls and curtains if crushed.

What You Should Know About Cluster Flies

  • Cluster flies emerge from the ground and enter homes in large numbers during early fall and spring.
  • They enter buildings through small openings or cracks and crevices near window or door frames, and open or unscreened windows/vents.
  • Once inside, cluster flies will gather together in an isolated place such as attics, wall voids, or false ceilings and begin to hibernate for the winter.
  • As you heat your house during the winter, hiding cluster flies may come out thinking it is spring. They’re attracted to light, so you will likely find them near windows and near lamps at night.

How to Prevent Cluster Flies From Entering Your Home or Cottage

  • Make sure that all screens fit properly and that there are no cracks or holes that would allow flies to enter your house.
  • Weather strip windows and doors.
  • Fill any cracks or crevices with caulking around doors, window frames, and other openings in the building structure.
  • Install insect screening or mosquito nets over air vents in soffits.

Miller Pest Control’s Annual Cluster Fly Special is Starting Now!

Treatments are generally done mid-August through mid-October in fall, and March-April in spring. Our effective cluster fly treatment includes a residual insecticide to window frames, door frames, cracks, crevices, soffit and fascia on the exterior, window frames, door frames, cracks, crevices, baseboards and attics on the interior.

Contact us to Learn More About Our Cluster Fly Treatment!