Disholcaspis eldoradensis
Agamic generation

[Photos of this gall appear on page 4 of the pdf]

GALL (Fig. 6). On last year's twigs in the intervals between buds, sometimes close together; usually on fast-growing relatively young trees. Galls are oriented along the twig, but seldom evenly or in rows. Number may vary from one to several dozen; relatively small numbers on robust twigs attain greater size and more perfect shape than those in large colonies on small twigs, which may be distorted by crowding; monothalamous. Circular emergence holes are usually at the ends of the galls. The hard broken shells and deep scars may remain on a tree for years; small twigs are often killed by the galls. Frequently the same tree is utilized for the agamic generation year after year, and develops a clipped stunted appearance.

Range: San Francisco area

Adults of the bisexual generation emerge during April and May, and oviposit in the twig bark. Gall colonies usually result from one female rather than from communal oviposition. First evidence of a gall is a slight swelling of the bark, which splits longitudinally as the gall develops. Very young galls are yellow, changing to green, brown, and shiny dark red by early autumn; thereafter the color becomes dull and darker. Agamic females emerge during November and December and oviposit in buds at that time.

Disholcaspis eldoradensis

Small, brown, cushion-shaped galls, sessile on twigs of Quercus kelloggii and Quercus lobata, hard and woody with the base broadly inserted in a slit in the bark. The top is flat and much pitted. Length about 4 mm., breadth about 3 mm., height about 3mm.

Hosts:
Quercus lobata
Quercus berberidifolia
Quercus durata
Quercus garryana

Disholcaspis eldoradensis

Quercus dumosa, garryana, lobata
Stem galls, detachable from the twig
Fig 86. Ellipsoid, rugose, 7 mm.

Fig.86. Q.lobata, dumosa, durata and garryana. Adults were cut out Nov. 10 (Lebec). Emerged Jan. 8-25 (Los Gatos). While growing from August to Nov 1 they secrete honeydew and a bee-keeper at Cottonwood reported that his bees made 50-1,0 pounds of honey per hive from this source. Altho a pure plant product it can not be sold as honey - it rotates the plane of polarization the wrong way. But bees winter successfully on it.

Ellipsoid, rugose, 7.0 mm

Hosts:
Quercus dumosa
Quercus garryana

Disholcaspis eldoradensis
[Page 101]

This cynipid wasp induces round to elliptical, monothalamous, detachable stem galls on valley, scrub, leather, and Oregon oaks in summer. These are galls of the agamic, or unisexual, generation.

Holcaspis eldoradensis sp. nov.

Gall. (Plate IX, figs. 6, 7.) On the twigs of Quercus kelloggii [erroneous; presumably should be Q lobata]. Hard woody and with the base broadly inserted in a slit on the branch. Rounded with the top very much flattened. Sides pale brown, wrinkled, summit dark brown and rugose. Centrally is a single larval cell. Width 4-7 mm. Height about 4 mm.

Habitat: Sonoma County, California.

Type: One female and gall. Collection American Museum of Natural History.