Pest Identification And Information

Cluster Fly

This species is a common pest throughout Europe, Canada and the U.S. (except in those states that border the Gulf of Mexico). It gets its name from the habit of forming tightly compacted “clusters” of hibernating individuals, usually found in wall voids and attics. They can be very frustrating for the homeowner who not only will notice cluster fly activity during the spring and fall, but also during warm, sunny days in the winter.

IDENTIFICATION:

• Often confused with houseflies, but are larger, more robust and about 3/8” (8mm) in length.

• Sluggish in their movements and fly slower than the housefly.

• Dark gray in color, non-metallic.

• Thorax will lack any distinctive stripes, but will have numerous short golden-yellow hairs along the sides and at the base of the wings.

• The dark gray abdomen will have irregular, lighter patches.

• Unlike the housefly, the Cluster Fly’s wings overlap at the tips when at rest.

• The wing’s 4^th longitudinal vein will have a characteristic forward bend near the tip, almost meeting the 3^rd vein at the wing margin.

• When crushed they will have a distinct Buckwheat Honey odor.

Habits:  

• As the days shorten, during early fall, Cluster Flies begin to look for a place to over winter, sometimes traveling up to a mile to do so.
• Are attracted to the “warm” sides of structures, usually the South, West and sometimes East walls.
• Will enter void areas such as attics, walls, window and door casings etc. through any number of small cracks, gaps, ill-fitting screens, vents and other openings, which make it very difficult to “pest proof” the structure. 
• They are a problem in the autumn, winter and spring; autumn, when seeking to over winter; warm, sunny days during the winter; and in the spring when emerging.
• May be stimulated to activity from any heat source, such as a furnace, but usually require the warmth of the bright sun heating up the walls.
• Once stimulated, they are attracted to the light from the windows and doors.
• During warm, sunny days they can be found on windows, crawling up the panes or frames, around lamps and light fixtures.
• There is NO reproduction in the walls or during their hibernation.  

biOLOGY:  

• Adults over winter or hibernate in sheltered areas.
• Emerge in the spring to mate.
• Eggs are laid in cracks in the soil and will hatch in about 3 days.
• Larvae are parasitoid upon certain earthworms.
• Egg to adult developmental time varies between 27-39 days. They can have up to 4 generations per year.

TREATMENT: