Identification: Adult cluster flies are about 3/8" long and robust in size. They are generally a dark gray in color and are known for their sluggish behavior.
Habits: Cluster flies lay their eggs in the soil where once they hatch they enter earthworms as a parasite. In the fall as the days grow shorter and the weather cools the flies will enter a structure to over winter usually in attics or wall voids. The cluster fly usually become a nuisance in the structure they have invaded during warmer, sunny days over the winter or on spring days when they are attempting to leave the structure.
Control: The most effective control for cluster flies is a exterior treatment with a residual chemical barrier applied prior to the flies attempting to enter the structure (generally mid to late august). Monroe Pest Control Co., Inc. can eliminate an infestation in one treatment and we warranty our work.