Loxaulus mammula

Quercus alba
Stem galls, woody stem swellings
Short, abrupt swellings at base of lateral branches in June. Many-celled.

[Photo caption]
Abrupt enlargement at the base of lateral branches in spring, many-celled, Adults emerge in July.

Loxaulus mammula

Galls on Quercus alba collected at Apple Orchard Camp in Bedford County, Va., on June 27, 1920, had the nutritive layer used up and larvae full grown. Adults emerged some time in July.

Cynips quercus mammula, n. sp.

Galls: Hard woody knots at the base of the young shoots on thrifty young white oak trees, Q alba. They affect both the lateral and terminal branches, and as they are of a hemispherical form, and of large size when compared with the branch which always grows out of their summit, they suggest the name above given. They are polythalamous, and the larval cells are arranged as though the eggs had been deposited around the bud before the leaves appeared. The white, thin-walled larval cells are imbedded in woody tissue from which it is almost impossible to detach them. The galls formed around the lateral buds are from one-half to three- fourths of an inch in diameter, but those around the cluster of terminal buds are often an inch in diameter, and instead of a single branch, several are often found growing out of a single gall. They do not seem to affect the growth of the branches the first year, but must seriously injure the tree the following year when the perforated galls begin to decay. This species was very common last year in a thicket which I have searched for galls every season for the last fifteen years without discovering it. The flies are of both sexes and they leave the galls in July.

Loxaulus quercusmammula (Bassett)

Cynips quercus mammula Bassett
Loxaulus mammula Weld
Loxaulus quercus-mammula Dalla Torre and Kieffer
Loxaulus quercusmammula Burks
Loxaulus ashmeadi Kieffer New Synonymy

Comments.--Kieffer described Loxaulus ashmeadi from New England and noted that it induces galls under the bark of twigs similar to those of L quercusmammula. Kieffer associated this species with Quercus robur, and suggested that L ashmeadi was introduced to North American from Europe along with its host oak. However, Loxaulus is not known from Europe. More likely, the oak host of this species is Q alba which was misidentified as Q robur. This species cannot be distinguished from L quercusmammula on the basis of the description given by Kieffer, suggesting that this species is a synonym of L quercusmammula.

Distribution.--NJ, MD, CT, VA, FL, New England

Biology.--Only the bisexual generation is known. It induces stem swelling-like galls on Quercus alba and Q stellata (this must be confirmed because this host record may refer to L vaccinii and not to this species). Galls occur in June, adults emerge in July.