Andricus schickae Nicholls, Melika & Stone, sp. nov.
Sexual generation

Diagnosis. No other sexual generations of Andricus species from California are known to induce unilocular integral leaf galls that are simply swellings of the petiole/midrib.

Gall. (Figs. 233–234). A unilocular integral gall in the leaf midrib or petiole, 3–4 mm long by ca. 2 mm across, visible as a slight longitudinal swelling that is a paler yellow-green than the rest of the leaf, sometimes also reddish. The gall causes distortion of the leaf lamina, in some cases bending it back through almost 180°.

Biology. Alternate asexual and sexual generations are known. The asexual generation bud galls develop on Q. garryana, mature in November, adults emerge the following spring. The sexual generation galls (Figs. 233–234) were found on Q. lobata leaves in late March-April; adults emerge soon afterwards. We expect both generations can be found on both Q. lobata and Q. garryana.

Distribution. USA, California (Los Molinos, Stockton, Cosumnes River Preserve) and Canada, British Columbia (Victoria).