Common Name: Hackberry gall psyllid
Scientific Name: Pachypsylla sp.
Description: 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.
Hackberry trees also harbor a number of gall-forming midge species (Diptera: Cecidomyiidae) such as the species that produces the thorn gall, Celticecis spiniformis (Patton). Immature stages of these species, when carefully dissected out of galls, appear maggot or grub-like and have no legs or antennae as do psyllid immatures.
Life Cycle: 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.
Habitat and Food Source(s): A number of Pachypsylla psyllid species occur on hackberry (Celtis spp.), including the hackberry nipple gall maker (P. celtidismamma (Riley), the hackberry blister gall maker (P. celtidisvesicula Riley), and the hackberry bud gall maker (P. celtidisgemma Riley).
Pest Status, Damage: Probably no hackberry tree is not infested with one of the gall-forming psyllids; causes galls to form on the leaves and petioles; adults occasionally become a nuisance in and around the home in the fall but are medically harmless.
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.
Management: None, not considered a major pest.
Literature: Johnson & Lyon. 1988.