Heteroecus pacificus

Naked, elongate, spindle-shaped. Cylindrical, with a constricted base and a greatly elongate, slender tip; entirely straight or curved; entirely naked, smooth, bright green splotched with brown to purple-brown, becoming dark brown upon aging. Solid, except for the cylindrical cavity extending from the base two-thirds to the tip, the larval cell not always at the very end of the cavity. On twigs of Quercus chrysolepis.

RANGE. — California: San Jacinto Mountains to Dunsmuir and Ukiah; probably wherever Q. chrysolepis occurs.

This species morphologically is closely related to dasydactyli, but altho Ashmead stated that the insects of pacificus ''cannot be separated from A. dasydactyli", his types of the two are distinct, showing differences which agree with those in the material I have bred from the two types of galls. Pacificus never bears any of the woolly covering which is characteristic of dasydactyli. Adult insects emerge in the spring, a couple of months earlier in southern than in northern California.

[Kinsey describes three varieties of this species; see paper for details]

Heteroecus pacificus

Quercus chrysolepis, tomentella, vacciniifolia
Fig 84. Spindle-shaped, bare, smooth. Mono. They are thought to vary greatly in shape from long and slender to the chunky form of the lower figure.

Fig.84. Q. chrysolepis. Also on vaccinifolia and tomentella. They are thought to vary greatly in shape from long and slender to the chunky form of the lower figure. They are gathered in the fall for rearing. Adults have been cut out in late November (Yosemite) and April 19 (San Gabriel Mts.). Adults emerged May 6 (California Redwood Park).

Heteroecus pacificus

This wasp induces long, spindle-shaped, monothalamous, glabrous stem or bud galls on canyon live and huckleberry oaks.

Shapes of these unisexual-generation galls can be severely altered by inquilines.

Host:
Quercus chrysolepis
Quercus vacciniifolia

Heteroecus pacificus [agamic]

Host: Quercus chrysolepis

The galls produced by the parthenogenetic or agamic generation show considerable morphological variation. Some are rather slender and elongated with a tapering point, whereas others are much more robust, with a shorter point. Using the shape of the gall as a primary distinguishing characteristic, Kinsey in 1922, described several varieties of Heteroecus pacificus. During the course of this study, females were obtained from galls that varied greatly in form (Figs. B, C, D). These galls were often on the same tree and sometimes on the same branch ; however, in each instance the typical alternate generation was obtained. Some galls of H. pacificus are almost globular with little or no point whereas others are so slender that they resemble a thorn. These extreme variations were not numerous in the area that was used for this work, hence insects from these types were not used. It is significant to note that the extremely slender forms did not yield inquilines or guests whereas the more robust types housed Synergus which suggests that these inquilines influence the shape of the gall. It is hoped that future rearings and studies will help to clarify the taxonomy of this species.

Range: La Crescenta, Pasadena, Switzer's Camp, Mt Wilson, Chilao in the San Gabriel Mountains, CA