[Synergus flavens, nigroornatus, and pacificus are listed as inquilines in galls of Heteroecus pacificus. It isn't clear which, if any, of these species cause the deformation of the gall that is the subject of this page.]

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