Andricus gemmiformis

On the trunk of the white oak (Quercus alba), May-October. Monothalamous. Green, sometimes tinged with red. Bud-shaped, elongate, pointed at the apex, thin-walled when mature and hollow inside and containing no separate larval chamber. When young it is more solid. Length 3-4 mm.

Habitat: Fort Lee district, New Jersey; Woodlawn, NYC

The gall is found on the trunk of large white oak, where the same is gnarly and young shoots sprout forth. It is imbedded in a cavity and may be easily removed. The gall looks exactly like the bud of a young sprout, and may be readily mistaken for such and overlooked. I have found fully developed galls May 30th and in June, and also late in October, 1915. One female emerged in October, 1915, from a gall collected in May, 1915, and one female in May, 1916, from a gall taken in October, 1915. Mr. L. H. Weld has also taken the gall at Evanston, Illinois. The male is unknown.

- William Beutenmuller: (1917) Descriptions of new Cynipidae (1917)^©

Reference: https://www.biodiversitylibrary.org/page/28154038#page/832/mode/1up