St Louis Pest Control Blog

Cluster Flies – An Over-wintering Pest

A cluster fly is best described as an over-sized house fly.  They do not bite and are truly a nuisance pest.  This fly will congrete in 100’s and sometimes in 1000’s.  They become a great nuisance as they become very active on mild winter days.  Like other over-wintering pests, these flies go for the first light outside the void that they were in and sometimes that light is from inside our house.

The best way to try and control these flies is prevent them from entering the structure.  Make sure caulk is good around windows and doors, utilities entering the home are sealed tight and there are no structure defects in the siding or soffit area of the home.  If cluster flies are a yearly problem in your home, use a pesticide to treat the sunny side of your home monthly during the fall months before they gain entry into your home.

Please call us if you have any questions or concerns regarding these pests at 636-343-7900 or go to for more information regarding our service options.


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