Cluster flies can be kept out of homes by sealing access points such as eaves and cracks, but once inside they usually need to be exterminated manually. They do not breed indoors, but may enter in large numbers to seek shelter.
Cluster flies are parasites of several species of earthworm. They lay their eggs in earthworms and feed the unlucky arthropods to their young. When the weather turns cold they frequently attempt to enter human dwellings to escape the frost.
Some methods of cluster fly extermination include:
- Hanging fly lanterns
- External spraying
Cluster flies tend to hide themselves in hard-to-reach places. They do not emerge often and can be difficult to find and kill, and their low-pitched buzzing is irritating to many people. A fly lantern, hung by a professional exterminator, can lure them out of hiding and to their deaths. Because they do not often take to the air, flypaper is not a useful extermination method.
The surest and easiest method of extermination is to hunt down the flies with a fly swatter or with a vacuum cleaner. The suction process kills the cluster flies almost immediately and can extract them from their burrows and lairs. Spraying the exterior of a house with pesticide, which should only be done professionally, can discourage flies from entering in the first place.