Galls appear as 1/8 to 1/4 inch swellings of tissue on leaves or petioles. They can be carefully cut open to reveal the pale, developing psyllid inside. Adults resemble tiny (3/16 inch long) cicadas and they can become abundant in the fall when they are attracted to homes, often crawling through window screening, seeking overwintering habitat.
Common leaf gall forming species overwinter in the adult stage in bark cracks and crevices. Adults mate in the spring and females lay eggs on the underside of expanding leaves. Nymphs hatch from eggs in about 10 days and begin feeding, which causes leaf tissue to expand rapidly into a pouch or gall around the insect. They develop through several stages (instars) before emerging as adults in the fall (September), although the hackberry bud gall maker overwinters inside the gall as a last stage (5th instar) nymph to emerge as adults in early summer. One generation occurs annually.
Adults occasionally become a nuisance in and around the home in the fall. Galls formed by these species are unsightly and occasionally cause premature leaf drop, but they do not appear to harm the health of the trees.
None, not considered a major pest.