Andricus gemmiformis

On the trunk of the white oak (Quercus alba), May-October. Monothalamous. Green, sometimes tinged with red. Bud-shaped, elongate, pointed at the apex, thin-walled when mature and hollow inside and containing no separate larval chamber. When young it is more solid. Length 3-4 mm.

Habitat: Fort Lee district, New Jersey; Woodlawn, NYC

The gall is found on the trunk of large white oak, where the same is gnarly and young shoots sprout forth. It is imbedded in a cavity and may be easily removed. The gall looks exactly like the bud of a young sprout, and may be readily mistaken for such and overlooked. I have found fully developed galls May 30th and in June, and also late in October, 1915. One female emerged in October, 1915, from a gall collected in May, 1915, and one female in May, 1916, from a gall taken in October, 1915. Mr. L. H. Weld has also taken the gall at Evanston, Illinois. The male is unknown.

Callirhytis gemmiformis

Conical, greenish becoming brown when mature, 3-4 mm high, from weak dormant buds on limbs or from adventitious buds on trunk of large trees of Q alba in Sept and Oct. Deciduous. Adults emerge the second spring, transforming the fall before.

Callirhytis gemmiformis

Quercus alba
Bud galls
Dormant bud gall on twigs or trunk, conical or blunt, greenish or red, cavity large, in fall.

[Photo caption]
On Q alba. Adults emerged the second spring in March and some the third spring. Females were twice seen ovipositing in buds of Q alba in Apr 11, 1938 and Apr 9 1944.

Callirhytis gemmiformis

Andricus gemmiformis

Galls of this species have been collected on Q. alba at Fort Sheridan, Kavinia, and Glen Ellyn, IL., and on Q. bicolor at Fort Sheridan and Wilmette. Galls collected October 29, 1916, contained pupae on September 17, 1917, and adults on November 15. These would probably have emerged in the spring of 1918. From galls collected in October, 1918, living flies were cut December 2. 1919, which agree with the type. As the claws are simple the species is here transferred to Callirhytis.

Andricus gemmiformis

Bud-shaped, elongate, pointed apically, thin-walled and hollow. Length 3 to 4 mm, on trunk of white oak.