Cynips vesicula

Neuroterus vesiculus

Cynipidae

Neuroterus

Quercus alba

Alabama

Arkansas

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Indiana

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Quercus bicolor

Nova Scotia

Quercus macrocarpa

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Quercus montana

Quercus prinoides

Quercus stellata

The Gall Wasp Genus Neuroterus

Cynipid galls of the eastern United States

Neuroterus vesicula (sexgen)

Cynips vesicula, n. sp.

Gall a small, smooth, reddish brown vesicle developed from the center of the buds of Quercus alba, surrounded at the base by the bud-scales. The color is sometimes a pale greenish brown. The walls of the gall are thin and the larva free, that is, having no larval cell. These galls are partially developed in the preceding autumn, and mature so rapidly in the spring that the insects emerge about the time the leaves of the oak begin to expand. 

Female appears early in April.

New Cynipidae (1881)

Cynips vesicula

White oak [Quercus alba]
Bud galls
Smooth, brown, central.

Insects affecting park and woodland trees

Neuroterus vesiculus

Cynips vesiculus
Neutoterus vesicula
Neuteroterus vesiculus

A monothalamous, subglobular gall appearing late in the fall in the center of a bud at or near the tip of the twig. Slightly corrugated, with a small projecting tip. Of the color of the bud. Cell comparatively large. Develops rapidly in the following spring. On white oak, Quercus alba. Rare.

Insect galls of Springfield, Massachusetts, and vicinity

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.

The North American Species of Neuroterus and their Galls

Neuroterus vesicula

Gall.--A small, thin-shelled, globular bud or bark gall. Monothalamous, up to 3 mm in dia; rather thin-walled, quite globular, the bud galls succulent and shrivelling on drying; 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; on white oaks and chestnut oaks.

Range.--MA to MI and TX. Probably throughout the eastern half of NA wherever white oaks occur.

Varieties:

Neuroterus vesicula variety affinis
[Bud gall on Q prinoides]

Neuroterus vesicula variety ocularis
[Bud gall on Q stellata]

Neuroterus vesicula variety vesicula
[Bud gall on Q alba]

Neuroterus vesicula

The galls of this species were described as starting their development in the fall, maturing quickly in the spring, the adults emerging about the time the oak leaves begin to expand. The writer has no evidence to show that this succulent gall develops partially in the fall, but they do occur and become full. grown before the buds start in the spring, the adults emerging either before or just as the buds open. They have been noted on Quercus alba., from which the species was described, at Ravinia, IL., containing both pupae and adults on April 24, 1915, the adults beginning to emerge April 29. Fort Sheridan galls contained pupae May 12, 1917, adults emerging May 18. In 1920 galls contained pupae at Cherrydale, Va., on April 11; and at Chevy Chase, Md., on April 18. At Washington adults were emerging March 27, 1921, and in the late season of 1924 on April 26. In emerging the flies chew out a round piece, which often remains as a hinged lid. On Q. montana galls were seen at Washington, with flies emerging April 22, 1923. On Q. bicolor the galls were common at Evanston, IL., being noticed as early as March 28, 1909, and March 27, 1910 (adults emerged and died in jar before April 20). In 1912 emergence was in late April, only one fly being reared from galls collected May 6. In 1913 galls were collected on April 15, some already showing exit holes, adults emerging by April 27. While gathering the galls an adult thought to be of this species was observed ovipositing in a bud. On Q. macrocarpa galls were found at Evanston May 1, 1913, and on April 27, 1915, three empty ones from which adults had recently emerged, and near by two adults perhaps from these galls were seen ovipositing in buds. Similar galls occur at Washington on Q. stellata, the flies emerging March 27-30, 1921, and April 25-29, 1924. 

Field notes on gall-inhabiting cynipid wasps with descriptions of new species

Neuroterus vesicula

Quercus alba, prinoides [Weld also lists Neuroterus affinis on Q prinoides as a distinct species], prinus [montana]
Bud galls
Almost globular, smooth, bare, brown, 2-3 mm, thin-walled, in early spring. Some slightly larger and light green and projecting beyond bud scales may be different.

Quercus bicolor, macrocarpa
Bud galls
Almost globular, reddish-brown and mottled, bare, 2.4 mm in dia, fleshy, thin-walled, in early spring.

Quercus stellata
Bud galls
Globular, smooth, brown, 2-3 mm in dia, thin-walled, in very early spring.

[Photo caption]
On Q bicolor. Also on Q macrocarpa, alba. They agree with specimens and photos from Bassett. N affinis is probably a synonym of it. Bassett's idea that these galls are partially developed in the fall needs verification. Hervey Brackbill marked three branches of white oak on Mar 3 on which there were 4 galls. On Mar 10 there were 10 galls. In the interval six had developed into visibility. He noted that field sparrows, goldfinches, tufted titmice and a cardinal seemingly fed on these galls (MD). Adults emerged May 10-6 (IL); Apr 14-23.

[Neuroterus vesicula](https://www.gallformers.org/gall/840) and [Andricus pisiformis](https://www.gallformers.org/gall/841) are both small, globular, often dark-surfaced bud galls found on white-group oaks in the spring. Based on the photos Weld provides of Andricus pisiformis, that species is distinguished by many prominent, near-circular, white-colored spots. According to Scott Digweed (personal communication) galls with that appearance on Quercus macrocarpa have been found to contain adults matching N vesicula. 

Adults reared from galls on Quercus stellata initially identified as A pisiformis due to the presence of spots were found to match N vesicula. However, on further examination, the spots on these galls (and many others on Q stellata) were seen to be somewhat distinct from those on A pisiformis. The spots on these galls are smaller, more irregular in shape and often less clearly bounded, with networks of lighter-colored cracks extending from spots, sometimes connecting many of them.

Aside from gall appearance, according to the literature, A pisiformis adults emerge up to a year after the appearance of the gall, while N vesicula adults emerge the same spring. A pisiformis is also easily distinguished by cross section. It contains a hard internal larval cell surrounded by a soft, fleshy external shell. 

Adults determined to be A pisiformis by adult anatomy were found to be very distinct from N vesicula in UCE genetic analysis by [Ward et al](https://www.biorxiv.org/content/biorxiv/early/2022/02/13/2022.02.11.480154.full.pdf).

Gallformers ID Notes