Recently, UK Extension Entomology personnel have received inquiries about small insects that seem to have invaded homes through window screens and other narrow entrances. When samples of these trespassers were obtained, they turned out to be hackberry psyllids, also known as hackberry nipple gall makers.
Hackberry Psyllid Basics
Hackberry psyllids are related to aphids and cicadas; they look sort of like a miniature cicada. They are about 3/16 of an inch long, with speckled wings, and large back legs that enable them to jump great distances relative to their size.
Psyllids go through incomplete metamorphosis, starting life as an egg, then developing through several nymphal stages before reaching adulthood. The adult psyllids lay their eggs in the developing leaf buds of hackberry (their only host) in the spring. The developing nymphs are housed inside of a plant growth called a gall, which they sort of “trick” the plant into building for them.
They develop over the summer, reaching adulthood by fall. The species overwinters as an adult and will usually hide amongst the crags and crevices of hackberry bark. Sometimes, though, they can be recruited to our homes and buildings.
Despite their living inside of galls on tree leaves, this insect isn’t normally considered to be a pest to hackberry trees. Safely tucked away inside their galls, they can feed without much harm coming to them or the plant. Most galls are a curiosity to us rather than a true problem for a plant.
However, hackberry psyllids are attracted to light-colored surfaces and are small enough that they can squeeze through the mesh that makes up most window screens. Their attraction to light colors can also mean they want to inspect your light-colored shirt. When they land on us they are known to probe us with their piecing-sucking mouthpart, which can lead to a “pinching” sensation.
Managing hackberry psyllids in trees is next to impossible for the average homeowner. Their development inside of their galls protects them from insecticides, and the lack of real damage means that they shouldn’t be considered a priority for treatment.
If you are dealing with them inside, you can try to follow our recommendations for pest proofing your home. This insect, though, presents a challenge since it can fit through the mesh of window screens. You can attempt to treat congregating psyllids on windows and siding with soapy water or contact insecticides such as Ortho Home Defense. Once they are inside, simply vacuuming or wiping up the bugs as you find them will be your best strategy. Bug bombs or other interior insecticide applications won’t provide relief. The psyllids can’t survive inside and won’t infest houseplants. If you deal with this on a frequent basis, it may be worth it to consider removing the hackberry trees in your landscape.
By Jonathan L. Larson, Entomology Extension Specialist