Callirhytis elliptica, new species

This species can be separated from Callirhytis ellipsoida Weld only by color markings which, however, seem to be constant. The galls also are similar but on a different oak [Quercus bicolor].

Host. — Quercus alba Linnaeus.

Gall. — An abrupt ellipsoidal swelling on small rootlets found an inch or two under the humus on forest floor underneath large trees. Brown, smooth, thin-walled when mature, monothalamous, and similar to galls of Callirhytis ellipsoida Weld on Quercus bicolor but the fly is different.

Type locality. — The type fly was cut out alive from a gall found at Highland Park, Illinois, October 22, 1916, on root of an undetermined oak. On May 11, 1919, five similar flies were collected at Glencoe, Illinois, ovipositing on buds of Quercus alba. On May 23, 1919, found similar galls on roots of white oak at Ravinia, Illinois. Some showed exit holes from which flies had recently emerged; others were full grown but contained a thick translucent nutritive layer and a barely visible larval cavity; others had a large cavity and a third of the nutritive layer left and a nearly full-grown larva which would probably transform in the fall and emerge next spring in early May. In the United States National Museum are three similar flies collected by J. G. Barlow at Cadet, Missouri, April 27 and May 5, 1883, ovipositing in buds of white oak. Also two from Nyack, New York, collected by J. L. Zabriskie, April 21, 1885, on buds of Quercus alba.

These galls were also collected at Marianna, Florida, October 10, 1919, on the roots of Quercus alba growing in deep woods. A dead adult was cut out on December 6, and mounted in balsam. This agrees with the type material and proves the type gall to have been on white oak. Galls collected in Washington, District of Columbia, on alba contained living flies on October 31, 1920.

Callirhytis elliptica

Quercus alba
"Root" galls
Single or in cluster of three or four on rootlets just under surface of ground in fall.

[Photo caption]
On rootlets of Q alba. Contained adults Oct 31 (DC). Adults were seen ovipositing in the buds of white oak in different years on March 26, 28, Apr 3, 9, 18, 19, 20. Some such buds were marked but what gall (if any) resulted was never determined. This is perhaps a synonym of Callirhytis ellipsoida Weld.