Leaf-gall
Guides
Pachypsylla celtidisvesicula
hackberry blistergall psyllid
Pachypsylla celtidisvesicula, commonly called the hackberry blistergall psyllid, is a species of aphalarid psyllid native to North America. The nymphs induce distinctive blister-like galls on the leaves of various hackberry species (Celtis spp.), within which they develop through five instars before emerging as adults. Adults strongly resemble the related hackberry nipplegall psyllid (Pachypsylla celtidismamma) but can be distinguished by the gall type their nymphs produce. Like other hackberry psyllids, adults overwinter in concealed locations and can become a temporary nuisance when they aggregate on building exteriors in fall.
Peracecis fugitiva
Hackberry Blister Gall Midge
Peracecis fugitiva is a gall midge in the family Cecidomyiidae, described by Gagné in 2013. It is commonly known as the Hackberry Blister Gall Midge due to its association with hackberry trees (Celtis species), where it induces blister-like galls on leaves. The species is part of a genus containing other gall-forming midges, though specific details of its biology remain limited in published literature.
Phylloteras
Phylloteras is a North American genus of gall wasps in the family Cynipidae, tribe Cynipini. These insects are specialized associates of oak trees (Quercus), inducing galls on leaves. The genus contains at least 4 described species, with estimates suggesting up to 11 species may exist. As members of the oak gall wasp tribe, they exhibit the characteristic life history of alternating generations between sexual and asexual forms, often with distinct gall morphologies for each generation.
Phylloteras cupella
urn gall wasp, banded urn gall wasp
Phylloteras cupella is a cynipid wasp that induces distinctive leaf galls on multiple oak species in western North America. The wasp measures 1.3–2 mm in length. Its galls display a characteristic ombré color gradient, transitioning from lighter tones at the top to darker shades below, with new galls appearing yellow, red, or mauve, aging to purple, and ultimately turning brown. The species was originally described as Trigonaspis cupella by Weld in 1926 and later transferred to Phylloteras.
Phylloteras volutellae
conical oak gall wasp
Phylloteras volutellae is a cynipid gall wasp native to North America that induces distinctive conical galls on the leaves of white oaks (Quercus section Quercus). The species is best known for the detachable, clustered galls formed on leaf undersides, each housing a single larva. Adults emerge in early January, though adult morphology remains undescribed.
Phylloxera caryaescissa
pecan leaf phylloxera, hickory phylloxeran
Phylloxera caryaescissa is a tiny, soft-bodied insect closely related to aphids that forms galls on hickory and pecan leaves. The species survives winter as eggs in bark crevices, with nymphs emerging during spring bud break to feed on new growth. Unlike the more destructive pecan phylloxera (Phylloxera devastatrix), this species attacks leaf tissue only and does not damage shoots or nuts. Extensive infestations may cause some defoliation but typically do not significantly reduce yield.
Polystepha pilulae
Oak Leaf Gall Midge
Polystepha pilulae is a gall midge in the family Cecidomyiidae, known for inducing distinctive leaf galls on oaks in the red oak group (Quercus sect. Lobatae). The species is found in eastern North America. The galls are circular, thick-walled structures formed on the upper leaf surface between veins.
Rhopalomyia audibertiae
Sage Leaf Gall Midge, White Sage Leaf Gall Midge
Rhopalomyia audibertiae is a gall midge in the family Cecidomyiidae that induces distinctive leaf galls on white sage (Salvia apiana). The species was described by Felt in 1907 and is commonly known as the sage leaf gall midge or white sage leaf gall midge. It has been documented in over 1,500 observations on iNaturalist, indicating it is relatively well-recorded where its host plant occurs. The midge is part of a genus containing numerous species that specialize on sagebrush and related plants in the genus Artemisia and Salvia.
Rhopalomyia pomum
Sponge Gall Midge
Rhopalomyia pomum, commonly known as the sponge gall midge, is a gall-forming insect in the family Cecidomyiidae. The species induces distinctive leaf galls on Great Basin sagebrush (Artemisia tridentata). It was described by Gagné in 1975 and is recognized as a valid species in current taxonomic databases.