Oak-apple-gall
Guides
Andricus quercuscalifornicus
California Gall Wasp
Andricus quercuscalifornicus is a cynipid gall wasp that induces large oak apple galls on white oaks, primarily the valley oak (Quercus lobata). The species is considered an ecosystem engineer due to its ability to manipulate plant tissue growth, creating complex microhabitats that support diverse insect communities. No male specimens have ever been recovered; reproduction occurs strictly through parthenogenesis.
Atrusca brevipennata
little oak-apple gall wasp
Atrusca brevipennata is a cynipid gall wasp that produces distinctive galls on oak leaves in western North America. Formerly known as Andricus pellucidus, this species was first described by Gillette in 1893 and later studied by Alfred Kinsey. The wasp is locally common in the American Southwest, with records extending as far north as Denver. It oviposits into leaves of shrub live oak (Quercus turbinella) and Gambel oak (Q. gambelii), inducing the formation of small oak-apple galls. The species is visually similar to Atrusca bella and may be confused with it in the field.
Atrusca capronae
striped oak-apple gall wasp
Atrusca capronae, commonly called the striped oak-apple gall wasp, is a cynipid wasp species that induces characteristic galls on oak leaves in southwestern North America. The species is most frequently observed in Arizona but occurs throughout the region where its host plants grow. The wasp's common name derives from the striped appearance of the galls it produces, though stripe intensity varies geographically. The species is considered fairly common within its range.
Torymus koebelei
Torymus koebelei is a species of chalcid wasp in the family Torymidae. The species was described by Huber in 1927. Torymus species are generally known as parasitoids of gall-forming insects, particularly gall wasps and gall midges. T. koebelei has been documented in the western United States, including California, where it has been reared from oak apple galls.