Cluster flies are small enough to crawl through cracks and little openings in walls, which often allows them to hibernate in secluded parts of houses, such as attics or wall cavities. On warmer days Cluster Flies then try to move toward light, which is when they can be seen around windows, often leaving stains on walls and curtains.
A combination of physical and chemical control methods can be used for Cluster Fly Pest Control. Silicone or other suitable exterior sealing compound can help block their entry points, but once the flies have entered a loft or attic space, pest control can be carried out with a range of insecticides and formulations. Most pyrethrum and pyrethoid based space sprays can be used to quickly kill exposed flies, but it is recommended that a pest control professional is consulted for the best solution.