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Cluster Flies

What are cluster flies?

Cluster flies are common household pests that become a nuisance for home and business owners from the late fall through early spring, when they overwinter inside structures. Cluster flies look similar to houseflies, but are larger, lacking the housefly’s metallic appearance, and they move sluggishly. The body of the cluster fly is gray and covered in yellow hairs, and may have some darker black markings that create a checkerboard pattern on their abdomens, and their wings overlap when resting. You can also identify these flies by the unpleasant, sickly sweet odor they give off when crushed.

cluster fly resting

Are cluster flies dangerous?

Unlike most species of flies, you can’t associate cluster flies with filth. They do not lay their eggs in decaying animal or plant matter, making them less of a threat to people than other species of flies. Adult cluster flies feed on pollen from plants, and females lay their eggs in the bodies of earthworms.

Cluster flies are mostly nuisance pests, but preventing them from invading is important since they do so in large numbers and, once inside, are difficult to eradicate. Also, their droppings will stain surfaces.

Why do I have a cluster fly problem?

In the late fall, cluster flies will gather, or cluster, together on the sunny exterior walls of homes and other buildings seeking warmth. They will crawl into the structures through cracks they find in the exterior walls, spaces around windows and doors, or openings along the roofline. Once inside, they will move into the quiet, low traffic areas of your home to spend the winter. When the weather warms back up in the spring, they migrate back outside.

Where will I find cluster flies?

Cluster flies that overwinter outside do so in beetle tunnels, the abandoned nests of small animals, or inside decaying trees. Cluster flies that have moved into our homes to overwinter will gather inside attics, behind wall voids, in dark closets, and other quiet areas. When overwintering inside, it is common to see these flies emerge from their hiding spots on warm, sunny days, and cluster around windows and window sills.

How do I get rid of cluster flies?

Get rid of cluster flies from your Central New York property with the help of a local, experienced professional. At Sweeney’s Pest Elimination, we have been protecting people and properties from our area’s most common pests for over 20 years.

If you are experiencing problems with cluster flies, our professionals will take care of the problem and offer you the services needed to stop them from returning each year. To learn more about our residential or commercial pest control solutions and how we can eliminate cluster flies from your Central New York property, contact us at Sweeney’s Pest Elimination today!

How can I prevent cluster flies in the future?

In addition to our professional home pest control services, avoid future problems with cluster flies by putting into place the following prevention tips:

  • Caulk the cracks you find in the exterior walls of your home that act as entry points.
  • Repair any loose or missing roof shingles and holes along the roofline.
  • Repair your damaged screens.
  • Place mesh covers over vents and chimney openings.
  • If you discover cluster flies in your home, the best way to remove these slow-moving insects is by contacting Sweeney’s Pest Elimination.

More pests

Stinging Insects
Cluster Flies
Centipedes & Millipedes
View our full pest library