Pachypsylla spp.

There are at least 10 species of psyllid in the genus Pachypsylla that are reported on hackberry. Three common species are known as the hackberry blister gall maker (Pachypsylla celtidisvesicula; galls are 3-4 mm wide and blister-like on the leaves and only slightly raised), the hackberry nipple gall maker (Pachypsylla celtidismamma; galls are taller than they are wide and much more raised from the surface of the leaf by comparison), and the hackberry bud gall psyllid (Pachypsylla celtidisgemma; galls begin to form in the bud tissue) (Johnson and Lyon, 1991). Both the hackberry blister gall and the hackberry nipple gall psyllids overwinter as adults in the crevices of rough bark. Occasionally both species will attempt to overwinter inside homes. In both species, there is one generation per year. When new hackberry leaves begin to unfold from the buds, mating and egg laying by these species will occur over the next few weeks. Eggs hatch in approximately 10 days and the nymphs (immatures) will begin to feed on the leaves. Depending on the species, a blister or a nipple gall is formed on the leaf in response to the insect's feeding. Both species will live inside their galls throughout the summer and typically emerge as adults by September. Near large, infested hackberry trees, the adult insects can be a public nuisance when they emerge in large numbers. Adult psyllids are approximately 4-5 mm. long and resemble miniature cicadas. They are also capable of jumping from a resting position and taking flight, and as such are sometimes referred to as jumping plant lice. Hackberry bud gall psyllids are present as adults in the last 2-3 weeks of June. Eggs are laid on leaves and nymphs crawl to newly formed buds to begin gall formation. These nymphs molt into the fifth instar by the fall and remain in that life stage over the winter. Hackberry psyllids use piercing-sucking mouthparts to feed on their host.