Phylloteras poculum (Osten Sacken, 1862), sexual generation

Synonyms: Cecidomyia poculum Osten Sacken (1862: 201), galls. Xystoteras poculum combination and description of adult females by Weld (1922a: 7); Phylloteras poculum combination by Lyon (1993: 133).

Gall. Galls of the asexual generation (Fig. 224) on Q. alba are as described by Osten Sacken (1862) and Weld (1922a).

Biology. See Weld (1922a) for the biology of the asexual generation. Galls of the asexual generation became evident on bur oak leaves in Edmonton in July, and were fully mature in September, when many separate easily from the leaf lamina, falling to the ground. Galls are susceptible to drying, and rearing experience suggests that desiccated galls produce no emergents. Females of the asexual generation overwinter and pass the entire subsequent summer in their galls, emerging in late autumn and winter – generally from late October to December with a peak in mid-November, but when a large number of galls was reared over winter 2016-2017 in Edmonton, a small number of females emerged in all months from January through April 2017. Weld (1922a) reared adults in Evanston, Illinois, in March. The brachypterous females were observed in Edmonton to crawl up through any accumulated snowpack, climb bur oak stems, and oviposit in buds. Emergence and adult female activity appeared delayed in autumn during periods of warmer weather, and was observed during a period of sustained temperatures ranging from -10°C to -17°C during early January 2017 in Edmonton. Galls of the sexual generation became apparent in early May in Edmonton, with adults emerging from mid-May through mid-June. This species has not been previously recorded from Q. macrocarpa; earlier records are from Q. alba and Q. montana. Another congeneric species, Phylloteras volutellae (Ashmead, 1897), is also found on Q. macrocarpa.

Distribution. USA: Virginia, New York, Vermont, New Hampshire, Illinois, Missouri (Burks 1979). Canada: Manitoba, 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)^©