Acraspis quercushirta (Bassett, 1864)

[Many synonyms; see table above]

Biology. See Bassett (1864), Weld (1922a, 1926), and Kinsey (1930, 1936) for the biology of the asexual generation. Asexual generation galls (Fig. 12) have been recorded on leaves of Q. chapmanii, Q. gambelii, Q. macrocarpa, Q. michauxii, and Q. montana. Adult females of the asexual generation emerged in Edmonton from late September to early November, with the peak occurring during the last half of October. Bassett (1864) noted that adult females of the asexual generation bore exit holes in their galls some time prior to emerging. This behaviour was observed in Edmonton as well, with females often remaining for days or weeks just inside emergence holes. Completion of emergence was often triggered by cooler temperatures. Leaves with galls have mostly fallen to the ground when the brachypterous females emerge in Edmonton, so they walk to a bur oak tree bole, climb it, and oviposit into bud scales, remaining active for up to 2–3 weeks, often at temperatures below freezing.

Galls of the asexual generation appeared on leaves starting in late June or early July.

Distribution. USA: Connecticut south to Virginia, Illinois, Michigan, Texas, Utah (Burks 1979), Colorado, New Mexico, Oklahoma (Kinsey 1930). Canada: Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick. Probably everywhere east of the Rocky Mountains in the USA and Canada where white oaks occur (Kinsey 1930) or have been introduced as urban trees (e.g., bur oak in Alberta).

- James Nicholls, George Melika, Scott Digweed, Graham Stone: (2022) Pairing of sexual and asexual generations of Nearctic oak gallwasps, with new synonyms and new species names (Hymenoptera: Cynipidae, Cynipini)^©