Quercus gambelii
Stem galls
Detachable
Fig 56.

Disholcaspis perniciosa

The galls were observed at Trinidad, Morley, Wetmore, and Garden of the Gods, Colo. ; Las Vegas, Glorieta, Rowe, and Tijeras, N. M. ; Flagstaff, Williams, Prescott, and Grand Canyon, Ariz. They were just starting at Trinidad on July 10 and at Wetmore contained adults on October 6. The flies probably emerge in November or early December. The galls were observed on Q. gambelii, fendleri, and grisea.

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.

Disholcaspis perniciosa
Round-gall wasp

Hosts: Quercus gambelii

Initially, galls appear ovoid but ultimately become round and dark brown.

Range: northern AZ, southern UT

Holcaspis perniciosa (Bassett)

Cynips quercus mellaria
Holcaspis perniciosus
Holcaspis perniciosa
Holcaspis monticola

Gall. (Plate IX, Figs. 8, 9.) In clusters on the twigs of oaks (Quercus undulata and Quercus gambelii). Monothalmous. Rounded with the apex more or less pointed or somewhat flattened, attached by a broad base to the twig which is enlarged into a shallow cup-like receptacle at the base of the gall. When fresh the gall is bright-colored, inclining to crimson or scarlet; when old, dark brown, hard, woody and containing a larval cell firmly imbedded in the rather hard cellular tissue. Smooth or slightly rough and sometimes with deep, irregular cracks. The adult escapes through an opening which it makes at the base of the gall. Diameter 5 to 8 mm.

Habitat Colorado; New Mexico; Utah; Arizona.

A distinct species, redescribed as Holeaspis monticola by Prof. C. P. Gillette. Riley, in 1880, briefly described the galls under the name Cynips quercus mellaria. This name should not be accepted since it is based merely on the plant deformation. According to McCook the galls exude minute drops of a sweet, watery secretion which is collected by the honey ant (Myrmecocystus hortideorum). This liquid is eagerly collected by the ordinary workers, carried to their nests in their crops and fed to the repletes, and otherwise serving as food when other sources are exhausted.

The types of H. perniciosus are in the American Entomological Society, and those of H. monticola are with Prof. C. P. Gillette and the American Museum of Natural History.