Andricus crystallinus

Gall:
The galls in which the bisexual generation of Andricus crystallinus develops are found mostly on the upper surface of leaves, singly or in small groups. The color is green with straw-colored apex. The gall has many long cottony, white hairs which project laterally and are longer than the greatest dimension of the gall. The gall is conical in shape, and distinctly canted to one side rather than being erect. The length is approximately 2.5 mm. with the base 1.0 mm. tapering to the tip. The position of the gall is indicated on the opposite (usually lower) side of the leaf by a pale-colored elliptical swelling.

Emergence takes place from the uppermost side of the slanted, conical gall. The gall has a single chamber.

Hosts:
Quercus douglasii
Quercus dumosa
Q. garryana

- Richard L Doutt: (1960) Heterogony in Andricus crystallinus Bassett (Hymenoptera: Cynipidae)^©

Reference: https://www.biodiversitylibrary.org/page/53497221#page/218/mode/1up