Jeffrey Hahn, Asst. Extension Entomologist
Small, fly-like insects have been appearing in people's homes this spring, especially around windows. Although they look like gnats or flies (one person thought they looked like fleas), these insects are hackberry psyllids. Despite their similarity to flies, these insects are more closely related to aphids and leafhoppers (they actually look like tiny cicadas).
Psyllids are about 1/8 inch long with a somewhat compact body. Their wings, a mottled brown with small black and white spots, fold up tent-like over their backs. During the spring and summer, they are associated with hackberry trees where they are gall producers on leaves. Adults emerge from their galls in the fall. Soon after that, they seek shelter to protect themselves from the winter; many end up in homes and other buildings, similar to boxelder bugs and lady beetles.
After they move into various cracks and spaces around the exterior of homes, psyllids remain dormant during the winter. As warm weather arrives in the spring, many of them become trapped inside homes as they become active (they can also emerge inside buildings during mild winter days). Fortunately, they do not live long indoors. They also do not reproduce inside buildings; the individuals you see in the spring have been inside your home since fall. They are harmless and just a nuisance.
When you see psyllids in the spring, the only necessary control is physical removal. Eventually they will either die inside or find a way to get outside. In either case, this problem will be over this soon. For more information about psyllids, including steps you can take in the fall to help prevent their entry into your home, see our publication on hackberry psyllids.