Andricus excavatus, new species

In the branches of the red oak, Quercus rubrum, toward the end of summer, appear long longitudinal slits or fissures, filled with irregularly shaped cells or kernels, which are usually smooth and polished, and generally of an oval, flattened form. These are the larval cells of a Cynipid, which fall to the ground in the fall, where the larvae within undergo their final transformation.

After the larval cells have fallen to the ground from their matrices, the twigs present broad grooves, fissures, and excavations, the relative length, depth, and appearance depending entirely upon the number of cells they had contained. One twig in the collection of the National Museum from which these larval cells had fallen exhibits a broad excavation over 2 inches long.

The flattened larval cell varies considerably in shape and size, but usually it is from 5 to 6 mm. long by 3 to 5 mm. in diameter.

Three female speciemns, in poor condition, reared June 6, 1883. The gall was collected somewhere in the New England States. I have, however, collected the same gall in North Carolina.

- William Ashmead: (1896) Descriptions of new Cynipidous Galls and Gall-Wasps in the United States National Museum^©

Reference: https://www.biodiversitylibrary.org/page/7294909