Pest ID: Cluster Fly
Adults are about 3/8″ (8mm) long. Dark gray, non metallic in color. Thorax lacking distinct stripes but with numerous short golden hairs. Abdomen had irregular lighter areas.
Places Most Commonly Found:
Because adults overwinter in sheltered places such as attics and wall voids a cluster fly infestation can be common. They usually occupy the southern walls and typically use the same structure year after year. This may be why you have problems with cluster fly control. If you have tried cluster fly traps without success it may because of the treatments you are trying. Eggs are laid in the soil where the larva feed on earthworms.
Most Active Period:
Usually a problem or nuisance in the autumn and early winter when they enter to hibernate and again in the spring when they attempt to leave the structure. They can be stimulated by warmth to resume activity anytime during the year thus cluster fly removal could be needed at anytime.
Difficulty of Control:
Easy to control with cluster fly treatments where exclusion methods are used.