Andricus serricornis

Plagiotrochus serricornis

Kernel Flower Gall Wasp (bisexual generation)

Cynipidae

Callirhytis

Quercus agrifolia

California

Quercus kelloggii

Oregon

Quercus wislizeni

Cynipid Galls of the Pacific Slope

New Pacific Coast Cynipidae (Hymenoptera)

Callirhytis serricornis (sexgen)

Andricus serricornis, new species

Galls (Pl. XXIV, Fig. 3). —Dense clusters of grain-like cells, yellow or yellow-brown. Bithalamous, though often several galls will fuse; the whole cluster rounded or elongate-oval, containing 20 to 40 or more cells. The cells are thin-walled, almost wholly hollow except for the partition separating the larval chambers. Apparently modified anthers of aborted, compacted aments, the clusters sessile on the young twigs of Quercus wislizeni and Q agrifolia.

Range: —California: Alpine, Three Rivers.

Galls collected February 24 at Alpine showed the adults to have emerged at an earlier date, but galls collected at Three Rivers on the following March 23 did not give adults until some (unrecorded) later date. It is likely that the emergence dates of spring galls for more northerly latitudes or higher elevations are regularly later. Although I do not have adults from the galls on Q. agrifolia the galls appear so identical as to make the identification at least specifically certain. I secured 99 females and 49 males, which is not the usual ratio for a bisexual form in this group of Cynipidae. Because of the early appearance of the gallon an evanescent part of the plant it is probable that this species has an alternate, agamic generation. The galls of this species resemble those of Neuroterus pallidus Bassett of the eastern United States, but in that species the clusters are borne at the ends of the aments instead of sessile on the young twig, distorting the whole ament.

Plagiotrochus serricornis

Andricus serricornis

The galls of this species have been collected by the writer on Q. agrifolia in the Santa Ana, Santa Monica, and San Gabriel Ranges, at Pasadena, Santa Anita (contained pupae April 20, adults emerging April 27), Newhall, Piru (flies emerging April 25, 1918), Fillmore, Ojai (galls about half grown on April 7, 1922), Carpinteria, Montecito, Santa Barbara, Gaviota, Santa Margarita, Paraiso Springs, Los Gatos, Palo Alto, and St. Helena; on Q. wislizenii at Camp Baldy, Bagby, California Redwood Park, and Ukiali (adults out May 10-13, 1922). 

Field notes on gall-inhabiting cynipid wasps with descriptions of new species

Callirhytis serricornis (Kinsey) 

Quercus agrifolia, wislizeni
Flower galls
Fig 35. Cluster 20-40 thin-walled cells.

[Photo caption]
Fig 35. Q agrifolia, kelloggii, wislizeni. Contained pupae Apr 20. Emerging Apr 25 to May 9, May 13 to 26.


Callirhytis serricornis
(Andricus serricornis)

This cynipid wasp induces clusters of hard, tiny, kernel-like monothalamous galls of the bisexual generation on the male flowers of coast live oak and interior live oak. The individual galls normally occur in grapelike clusters at the upper end of the catkins.
