Cynips quercus tubicola n. sp.

Host: Quercus obtusiloba [stellata]

Clusters of yellow, tubular galls with red spines, on the underside of the leaves. The gall is a perpendicular tube 0.3 to 0.4 [no unit given] long, slightly narrowed at its point of attachment, open at the other end, yellowish and covered on its outer surface with numerous red spines. If cut open longitudinally, its inside appears divided into three compartments like so many floors, by two horizontal partitions; the compartment nearest to the base is empty, the intermediate one contains the insect and the third one is open at the top.

If the red spines are removed with a knife and the surface of the gall examined under a strong lens, it shows dense longitudinal fibres and numerous little pale yellow crystals. The substance of the gall itself is hard, as if crystalline. From 30 to 40 of these galls are found sometimes on the underside of a single leaf. I frequently found them near Washington, in October and obtained the fly soon afterwards, each tube containing a single fly.

- Baron Osten Sacken: (1861) On the Cynipidae of the North American Oaks and their Galls^©

Reference: https://www.biodiversitylibrary.org/item/22852#page/80/mode/1up