Gall. Issuing from a bud on the terminal twigs of red oak (Quercus rubra) in September and October. Almost globular and usually with a small nipple at the apex. Green and succulent and spotted with red when fresh, and with the outer shell moderately thick. Internally with a central larval cell held in position by radiating fibers. When old the gall becomes brown and shriveled in appearance. Diameter about 16 to 18 mm.
The gall somewhat resembles that of A inanis, but differs by being smaller, a thicker outer shell and much stouter radiating fibers. It is an autumnal species and the galls readily break off when touched, or it falls with the leaves or before them. It is a bud gall, while that of A inanis occurs on the leaves in spring. The adult emerges late in August and early in September.
Habitat: CT, NJ, NY, NC, PA, MI, IO”
- William Beutenmuller: (1909) The species of Amphibolips and their galls©