What Are Cluster Flies?

Description

• Cluster flies have a gray to black color. The thorax (rear portion) of the fly will have golden hairs, indicates Colorado State University. These flies are larger than the common house fly. Their wings will also overlap when resting, unlike the house fly. If you kill a cluster fly, it will produce a "buckwheat honey" odor, states Ohio State University. If these flies accumulate in your home, this odor can become overwhelming.
  
  

Biology

• These flies parasitize earthworms. A female cluster fly will lay its eggs near an earthworm. When an egg hatches, the cluster fly larvae will enter the earthworm. An earthworm will become the host for larvae. Maggots will feed on an earthworm for up to three weeks before emerging to pupate. When the adult emerges, the cycle will begin again. Cluster flies do not develop within garbage or decaying matter.
  
  

Other Facts

• It's common to see these flies buzzing near light sources. They have a sluggish and awkward nature when flying. They will carelessly fly into objects and fall lazily to the ground, according to the University of Rhode Island. After falling to the ground, the fly will exhaust itself with its spinning. Cluster flies have a tendency to flock toward the warmer sides of a residence.
  
  

Control

• When these flies find their way into your home, it can become difficult to remove them. While cluster flies don't cause major damage, they can leave behind excrement and discolor furnishings and carpets if crushed. Using a vacuum to suck up these flies can offer temporary control. Not crushing these flies will also help avoid attracting other cluster flies. Repairing damaged window screens and using caulk to seal up cracks in your home's foundation can also help keep the flies from entering your home.