The cluster fly is often mistaken for the common house fly but they are more sluggish and often appear to fly very slowly. They can overwinter in vast numbers in lofts, cellars and dark voids. These flies are of no particular harm but can be alarming because of their great numbers. Generally noticed on the first warm days of spring when they congregate on the inside of windows. Frequently found in window frames, particularly sash windows.
It is very difficult to prevent cluster flies from entering a roof/loft space, however, once the flies are inside control is fairly simple. Most household fly sprays will do the job, smoke formulated insecticides can also be used. Always read the label.
We do not treat cluster flies. You can find other professionals that are able to treat an infestation online or in a local directory.