Compsodryoxenus illinoisensis, new species

Host. — Quercus macrocarpa Michaux.

Gall. — Cells in the thickened bark at the crown of small sapling causing an abrupt swelling of four to five times the normal diameter of the shoot and extending for a distance of as far as 30 cm., or in bark at base of young shoots in such numbers as to cause a noticeable swelling. Almost wholly buried under the debris on forest floor. Resembles the gall of the sexual generation of Callirytis futilis (Osten Sacken) on roots of large trees of Quercus alba, except that cells are smaller.

Type locality. — Winnetka, Illinois. One gall was found October 22, 1914, and contained living adults. Another was found November 1, with adults emerging, and they continued to come out until November 11. Another gall was found at Fort Sheridan, Illinois, on October 3, 1914, and living flies were cut out of it on October 29.

Loxaulus illinoisensis

Quercus alba, macrocarpa
"Root" galls
Cells in greatly thickened bark at base of saplings underground, in the fall.

[Photo caption]
On Q macrocarpa. Adults emerged Nov 1-14.

Loxaulus illinoisensis (Weld)

Compsodryoxenus illinoisensis Weld
Loxaulus illinoisensis Weld

Distribution: IL

Biology.--Only the unisexual generation is known. It induces subterranean stem swelling-like galls, usually at the base of young sprouts of Quercus macrocarpa. The abrupt stem swelling induced is approximately four to five times the diameter of the shoot and nearly 30 cm long. Galls mature in fall and adults emerge from the end of October through November.