Holcaspis rubens, n. sp.

Galls.--The galls are globular, from 10-14 mm in diameter, composed of a dense corky substance, each with a single larval cell that is easily detached from the surrounding portions, attached singly to small twigs. They have either a smooth or rough exterior, and are of a light straw color, usually considerably tinted with red. They resemble very closely the galls of Holcaspis rugosa Bass [Disholcaspis quercusglobulus]. The flies, however, are very different.

Location: CO

The flies began to emerge from the galls October 20th.

- CP Gillette: (1893) Colorado Cynipidae--Part II^©

Reference: https://www.biodiversitylibrary.org/item/20183#page/343/mode/1up