Genus Pachypsylla - Hackberry Psyllids

Pachypsylla Riley 1885

Between 7-13 spp. in our area (1), 8-14 total(2) (see remarks)

2-6mm (3)

Key to species, adapted from Tuthill, 1943 (3)

1a. Head and thorax pubescent, not shining; marginal cells of forewing very elongate; forming galls on leaves or leaf petioles ... 2

1b. Head and thorax glabrous, marginal cells not elongate; forming galls on buds or twigs ... 3

2a. Large species (>5mm), wings rhomboidal, forming galls on leaf petioles: Pachypsylla venusta

2b. Smaller species (typically between 2-4mm), forming galls of various types on leaves ... Pachypsylla celtidismamma complex (includes P. celtidismamma, P. celtidisvesicula, P. celtidisasterisca, P. celtidisumbilicus, and P. cohabitans. See remarks below)

3a. Forewings uniformly brown, forming glabrous galls on axillary buds: Pachypsylla celtidisgemma

3b. Forewings maculate ... 5

4a. Branches of medial cell sinuate, forming galls beneath bark on twigs: Pachypsylla celtidisinteneris

4b. Branches of medial cell not sinuate ... 6

5a. Forewings finely mottled apically (galls are unknown): Pachypsylla dubia

5b. Forewings with large maculae, forming pubescent galls on axillary buds: Pachypsylla pallida

Throughout North America, especially in the east (2)

Celtis (Hackberry)

Gall, nymphs, adult

With our current knowledge, adults belonging to the Pachypsylla celtidismamma complex are indistinguishable from each other, though the galls themselves are distinct. Historically, most authors have treated all leaf-gallers other than the blister-galler as synonyms of a single species, P. celtidismamma. However, allozyme frequency testing and electrophoretic analysis suggests that there may be up to seven cryptic leaf-galling species, including an inquiline species; further genetic testing may eventually reveal the extent of species boundaries within this group(4)(5).