Andricus quercuscalifornicus

The cynipid gall-inducer, A. quercuscalifornicus, induces a 5–250 cc (often apple-sized), multilocular (many wasps per gall) gall on the twigs of valley oak (Quercus lobata), a California endemic, where galls become apparent on twigs with bimodal peaks of development which occur in the late spring and mid summer (Rosenthal and Koehler 1971b). It has also been collected from closely-related oak species, Q. douglasii, Q. berberidifolia, and Q. garryana (Weld 1957). Gall abundances vary widely between individual trees, and extremely high gall densities of more than 50 galls per cubic meter of canopy may be supported by some trees. The range of A. quercuscalifornicus spans most of California with the extremes of southern Washington and northern Mexico (Russo 2006).

Andricus californicus Ashm.

Quercus douglasii, dumosa, durata, engelmanni, garryana, lobata
Stem galls, detachable from the twig
Fig 68. Large, ellipsoid, smooth, bare, tan. Poly.

68. On all the white oaks. Common in Oregon and as far north as Tacoma, Wash. on Q- garryana. Galle from Mexico have been taken at quarantine at Nogales, Ariz. Galls start to develop in May. Adults emerge in October.

Andricus quercuscalifornicus

Polythalamous, sessile on the branches of the Californian White Oak. Sub-globular, but varying much in form and size. A common form is what may be termed balloon-shaped, the upper part perfectly globular, the lower tapering more or less to the sessile base. They often occur of a long compressed oval form : these are placed longitudinally on the branch and the length is two or three times their breadth or thickness. Those of this form are often of monstrous size, being ten or twelve inches in their greatest circumference.

The globular galls are from one to two inches in diameter. In color, they are of an opaque white. They are usually smooth, but specimens occur that have a more or less warty surface, and others are found that have slight yellowish-brown ridges. Internally are of a uniform, dense cellular structure, and the not very numerous larval cells (from one to a dozen) lie closely embedded in this cellular substance.

Andricus quercuscalifornicus
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New galls are succulent, green or red, smooth, and glossy. By late summer, these lightweight solid galls turn creamy white and occasionally have a few short knobs or wart-like protuberances.

Hosts:
This species occurs on nearly every species of white oak in the Pacific States.

Andricus californicus

Hosts: Quercus lobata, douglasii, garryana, dumosa

GALL. — Large, globose to reniform, smooth, twig gall. Monothalamous, or polythalamous, containing from one to a dozen larval cells. Irregularly rounded, ovate, ellipsoid to reniform, all sizes, up to 65. mm. in diameter by 113. mm. long; the surface smooth, sparingly, shallowly roughened; reddish to yellow and brown. Internally more or less filled with compacted, soft, crystalline, brown, yellow, or white material, woody from the point of attachment to above the center of the gall; the larval cells oval, averaging 4.-5. mm. long by 3. mm. wide, more or less radiantly in the woody tissue, toward the center of the gall. Laterally, on twigs of several white oaks.

RANGE. — From the Mexican border of California to Washington.

[Kinsey goes on to describe several varieties with distinct host, range, and gall morphologies; see paper for details]