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Genus Pachypsylla - Hackberry Psyllids

Plant Louse - Pachypsylla Gall - Pachypsylla venusta hackberry blister galls, Pachypsylla celtidisvesiculum - Pachypsylla celtidisvesicula hackberry psyllid - Pachypsylla Female, Hackberry Petiole Gall Psyllid? - Pachypsylla venusta - female Psylloid - Pachypsylla Pachypsylla celtidismamma Hackberry Petiole Gall Psyllid - Pachypsylla venusta
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hemiptera (True Bugs, Cicadas, Hoppers, Aphids and Allies)
Suborder Sternorrhyncha (Plant-parasitic Hemipterans)
Superfamily Psylloidea
Family Carsidaridae
Subfamily Pachypsyllinae
Genus Pachypsylla (Hackberry Psyllids)
Explanation of Names
Pachypsylla Riley 1885
Between 7-13 spp. in our area(1), 8-14 total(2) (see remarks)
2-6 mm(3)
Key to species adapted from (3)
1. Head and thorax pubescent, not shining; marginal cells of forewing very elongate; forming galls on leaves or leaf petioles ... 2
Head and thorax glabrous, marginal cells not elongate; forming galls on buds or twigs ... 3
2. Large species (>5mm), wings rhomboidal, forming galls on leaf petioles: P. venusta

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

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

Forewings maculate ... 5
4. Branches of medial cell sinuate, forming galls beneath bark on twigs: P. celtidisinteneris

Branches of medial cell not sinuate ... 6
5. Forewings finely mottled apically (galls are unknown): P. dubia
Forewings with large maculae, forming pubescent galls on axillary buds: P. pallida
Throughout North America, mostly eastern(2)
host: Celtis (Hackberry)
Life Cycle
Gall -- nymphs -- adult
Within the Pachypsylla celtidismamma complex, adults are indistinguishable, yet the galls 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).
Works Cited
1.American Insects: A Handbook of the Insects of America North of Mexico
Ross H. Arnett. 2000. CRC Press.
2.Ouvrard D. (2013) Psyl'list - The World Psylloidea Database
3.The psyllids of America North of Mexico: (Psyllidae: Homoptera) (Subfamilies Psyllinae and Triozinae)
Tuthill, L.D. . 1943. Iowa State College Journal of Science 17: 443-660.
4.Biosystematics of hackberry psyllids (Pachypsylla) and the evolution of gall and lerp formation in psyllids
Yang, M.-M. & C. Mitter. 1993. The Ecology and Evolution of Gall-forming Insects. United States Dept. of Agriculture.
5.The Authority and Types for the Hackberry Gall Psyllid Genus Pachypsylla (Riley) (Hemiptera: Psyllidae)
Thomas, D.B. 2011. Entomological News, 122(3):279-287.