Neuroterus affinis

Quercus prinoides
Bud galls
"Monothalamous, round, thin-walled, in the buds, usually hidden by bud scales, brown. Half-grown in the fall. Adults emerge as leaves begin to expand." Type host, entered from lit.

[In the caption for Neuroterus vesicula, Weld notes that Neuroterus affinis is "probably a synonym of it."]

[Figure 83, for "Neuroterus sp."] On Q bicolor. Also on Q alba. This may be Neuroterus affinis but galls are light green instead of brown. Adults of both sexes emerged Apr 27-May 6 (IL); Apr 14-23 (DC). Blackburnian warblers seemed to be opening these galls for the larvae inside.

Cynips affinis n. sp.

Monothalamous, round, thin-walled galls in the buds of Quercus prinoides, usually partly hidden in the scales of the bud, but in some instances standing out round and free like a little blister on the twig, in size only large enough to hold the larva within, and in color dark brown and grayish spots, or wholly brown. These galls are half-grown in the autumn and develop so rapidly in the spring that the insects come out just as the leaves begin to expand.

I should have been disposed to consider this species a variety of C vesicula, which, both in gall and in insect, it closely resembles, had not late discoveries shown that dimorphic species often in one generation closely resemble each other and in the next develop characters that fully establish their non-identity.

Neuroterus vesicula variety affinis

Cynips affinis
Neuroterus affinis
Neuroterus vesiculus

Gall.--As described for the species: [A small, thin-shelled, globular bud gall. Monothalamous, up to 3 mm in dia; rather thin-walled, quite globular, the bud galls succulent and shrivelling on drying; almost smooth, but microscopically pebbled; the bud galls colored light green and drying light or dark brown; internally entirely hollow, without a distinct larval cell. In a terminal or lateral bud, partly covered by normal bud scales.]

Range.--CT Probably confined to a northeastern area of the US

Bassett stated that these galls start growth in the autumn and mature early in the spring, the insects emerging by the time the leaves begin to expand. The variety is undoubtedly confined to Quercus prinoides, a distinct oak which always has a unique cynipid fauna. There are so many well-defined differences between vesicula and affinis that it would be a great loss to consider the two as synonyms. Bassett saw that the two insects are related but distinct, and it is a step backward to ignore such non-identities.

Neuroterus vesiculus

Cynips vesicula
Cynips affinis
Neuroterus vesicula
Neuroterus affinis

Gall. In the buds of white oak (Quercus alba), dwarf chestnut oak (Quercus prinoides) and swamp white oak (Quercus platanoides [bicolor]), usually partly hidden in the scales of the bud, sometimes standing out round and free like a blister on the twig. Monothalamous, round, thin-walled and of a dark brown or greenish brown color, sometimes with grayish spots. In size it is only large enough to hold the larva within.

Habitat. CT, NY, NJ, IL, MI, IO

The galls of this large species of gall-fly are half-grown in the autumn and develop so rapidly in the spring that the insects come out just as the leaves begin to expand. I can find no differences between the adults and galls of N affinis and vesiculus, and they are, as surmised by Bassett, one and the same species. I have taken the galls in the vicinity of New York late in April. The flies begin to emerge about May 6.