Have you seen large black flies in your home? They’re a little larger than houseflies and they don’t seem to move as fast. These are the kind that like to mill around on your screens and windows. What are they? These large black flies are black cluster flies.
What Are Cluster Flies?
Cluster flies will start to get more numerous towards the fall, so be on the lookout this summer. They like to find parts of the house that aren’t used as often, such as in between walls or in attics. This gives them their other name: attic flies.
Crushing them is not a great plan because they leave more of a mess than houseflies. They’ll stain and smear, making them an even greater pain. Houseflies also like to be outside more than black cluster flies, whereas cluster flies target unused spaces in homes and congregate there.
Where do Cluster Flies Come From?
Cluster fly eggs are laid in soft soil toward the end of summer. The eggs hatch quickly – in only a handful of days. The larvae feed themselves on earthworms, entering the worms and camping out between their muscles and intestines. They’ll feed on the earthworm for many days before pupating and turning to flies in the soil. They reach adulthood within 39 days at most.
What are the Risks of Cluster Flies?
Cluster flies don’t lay eggs in food like houseflies, making them less directly dangerous. They are not known to bite people or pets. These flies will produce a sickening smell as they linger in an area, particularly as they deposit fecal matter.
Large black cluster flies feed on flower nectar, so won’t usually be attracted to garbage like houseflies are. They may be attracted to sugary drinks and snacks, however, much like bees and wasps.
If you notice black cluster flies gathering on a window, you can just vacuum them up. If you notice them crawling into any crevices of the house, however, it’s time to call a local pest control specialist in Massachusetts.