Dryocosmus asymmetricus

This wasp induces integral, polythalamous stem galls that rupture and split, exposing a nest-like cluster of larval chambers resembling a clutch of brown, elliptical eggs.

Host:
Quercus chrysolepis

Dryocosmus asymmetricus

Quercus chrysolepis
Stem galls, woody stem swellings or cells under the bark
Fig 53. Cracks open, cells nested.

Fig.53. Quercus chrysolepis. Bark cracks open and discloses a nest of cells. (Not to be confused in the field with Andricus spectabilis Kinsey (Fig. 59). Adults were cut out Apr. 25 Apr. 23 (Santa Lucia Mts)

Dryocosmus asymmetricus

Quercus wilcoxii [chrysolepis]
Stem galls
Stem swellings
Fig 43.

Plagiotrichus asymmetricus, new species

GALL. — Stem swelling containing compact clusters of larval cells. Polythalamous. The swelling covered with bark normal in appearance; a gradual enlargement, often asymmetrical on the stem; up to 30. mm. long, by 20. mm. broad. Internally, the larval cells in compact masses, each cell with a distinct and sometimes separable lining, not very thin walled; the cells usually densely clustered. On young stems of Quercus chrysolepis.

RANGE. — California: Pasadena and San Bernardino to Dunsmuir and Ukiah. Probably wherever Q. chryslepis occurs.

The gall of this species does not differ materially in external appearance from the galls of two other Pacific Coast species found on the same host: Andricus spectabilis Kinsey and Plagiotrichus chrysolepidicola (Ashmead). The species presents the typical condition of distinct varieties wherever it occurs in a distinct faunal area. Between the adults of the first two varieties there are few differences, but their galls are very distinctive; between the galls of the second and third varieties there are not appreciable differences, but their adults are very distinct. In the first instance the species varies more physiologically than morphologically, in the second instance the morphology varies more than does the physiology.

[Kinsey describes two morphologicallly identical varieties of this gall; see paper for details]