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Cluster Fly Facts

  • Slightly larger than a common housefly.
  • Love traveling in large groups and can be found both inside and outside of homes.

Cluster Flies

Most homeowners will see cluster flies migrating to the sunniest portion of a home. As the name would imply, cluster flies love traveling in large groups, and they can be found both inside and outside of homes. Unlike other types of insects, cluster flies love flying during winter. It’s common for homeowners to witness these flies crawling out of attics and wall voids. Experts believe cluster flies originate from Europe, but through different types of ships, cluster flies have been able to migrate to North America. The earthworm is known to be the preferred host for cluster flies.

What Are Cluster Flies?

A typical cluster fly is a tiny bit bigger than a common housefly and moves very slowly. The golden, short hairs on a cluster fly’s thorax make it easy to identify. Put simply, the thorax is what the cluster fly’s wings and legs are attached to. The larvae that grow into cluster flies develop inside of earthworms. The biggest difference between common house flies and cluster flies is the fact that cluster flies always fly in the direction of household windows that contain the most sunlight. The northern portion of the United States is where the highest concentration of cluster flies can be found.

Cluster Fly Infestation

Fortunately, cluster flies do not cause structural damage, and they certainly don’t bite. However, no homeowner wants to deal with a cluster fly infestation. In most situations, cluster flies hibernate in parts of a home or building that cannot be reached, which makes them particularly hard to control. It’s likely that cluster flies will try to hide under insulation or inside of walls, and until they make an appearance, they’re pretty resistant to treatments.

How to Get Rid of Cluster Flies

Mechanical exclusion can help to get rid of cluster flies. Many homeowners use physical barriers to repel a variety of common insects. Homeowners can seal cracks around utility pipes, siding, doors and windows. Applying screens that are made of vine mesh can help. An indoor infestation of cluster flies can potentially be controlled with specific insecticides.

Many homeowners choose to use a powerful fogger that is capable of controlling these insects. However, it’s almost always a better idea to contact professional pest control experts.

Cluster Fly Health Concerns

There are no known health concerns associated with cluster flies; these insects are not drawn to garbage, and they don’t bite animals or people. In most cases, cluster flies are simply irritating. When moving in large groups, these flies can overrun almost any room in a home, which makes it almost impossible for someone to enjoy being in the same room as the flies. One of the best ways to remove an infestation of cluster flies is to contact an expert.


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