Why Do I Have Cluster Flies In My Home?


At American Pest Solutions, we think that cluster flies are an interesting species of fly, and we would like you to learn more about them because (A) they really are interesting and (B) because learning about these flies can help you to prevent them from invading your home! The first thing to know about cluster flies is that they aren’t known for having a peppy, go-getter attitude. In fact, it’s just the opposite. Cluster flies are slow-moving and almost clumsy. They don’t have the agility necessary to fly around your home effortlessly like the slightly smaller house fly has. The second interesting fact about cluster flies is that the adult female lays her eggs in the soil; and when the larvae hatch, they find an earthworm and burrow into it to feed on it as they develop - a slightly horrifying, yet extremely interesting fact!

Now that you know a little bit more about the unique characteristics of a cluster fly, you are probably thinking, “Yes, they are interesting, but why do I find them in my home and what are they looking for?” The good news when it comes to cluster flies is that when the weather is warm, they mainly stay outside and don’t cause too much trouble for homeowners. Cluster flies don’t usually become a nuisance inside homes until the weather cools down in the late fall. As their name suggests, cluster flies will “cluster” together in large groups on the sunny exterior walls of homes and other buildings to try and stay warm. They then often make their way inside through open windows and the small spaces found around windows and doors. So to answer your question, warmth and a free place to stay for the winter is what cluster flies are looking for!

Once inside your home, cluster flies will gather in attic spaces, behind walls voids, or in crawl spaces to overwinter. If there is a warm spell during the winter months, you may find them emerging from their overwintering spots and gathering in large groups near windows and lights. Having cluster flies in your home is not dangerous because they don’t bite and because they aren’t known to spread diseases that can't make people sick like houseflies do. They are, however, a huge nuisance to have living in your home, and they can leave fecal stains on walls and furniture as they move about.

A good way to keep cluster flies out of your home is to seal up any openings found on the exterior of your home that may allow them inside. Make sure that window screens are intact and caulk any openings around windows, doors, and utility entrances. The best solution to prevent cluster flies from getting into your home is to put in place a year-round pest control plan from the pros at American Pest Solutions. We can protect your home from invading cluster flies and other common household pests throughout the entire year. Contact us today to learn more about our Pest Guard home pest control plan, or any of our other industry leading pest control solutions!