Holcaspis perniciosus n. sp.

Monothalamous, roundish galls, sessile by a broad base on the twigs of a dwarf oak growing in southern Utah. Apex in some specimens slightly elongated and compressed laterally, but usually blunt cone shaped. The twig itself is enlarged into a shallow cup-like receptacle at the base of the gall. In all my specimens (dry ones from which the insects have escaped) the galls are smooth, or only slightly rough, and with deep, irregular cracks and a dark reddish brown color. The large larval cell is firmly imbedded in the rather hard cellular tissue. The insects escape through a large opening which they make near the base of the gall. These galls bear a pretty close resemblance to the parasitized galls of H duricoria Bass. Judging from their abundance on the twigs sent me they must be quite injurious to the trees infested.

- HF Bassett: (1890) New Species of North American Cynipidae (1890)^©

Reference: https://www.biodiversitylibrary.org/item/32322#page/76/mode/1up