Neuroterus thompsoni

Cynipidae

Neuroterus

Quercus montana

Alabama

Connecticut

Delaware

Georgia

Illinois

Indiana

Kentucky

Louisiana

Maine

Maryland

Massachusetts

Michigan

Mississippi

New Hampshire

New Jersey

New York

North Carolina

Ohio

Pennsylvania

Rhode Island

South Carolina

Tennessee

Vermont

Virginia

West Virginia

Quercus muehlenbergii

Arkansas

Florida

Iowa

Kansas

Minnesota

Missouri

Nebraska

New Mexico

Oklahoma

Texas

Wisconsin

Ontario

Quercus prinoides

Quercus stellata

Cynipid galls of the eastern United States

The Gall Wasp Genus Neuroterus

New species and synonymy of American Cynipidae

Neuroterus rileyi (agamic)

Neuroterus thompsoni, new species

Neuroterus rileyi (error) [Kinsey separates N thompsoni from rileyi here but subsequently synonymizes it as a variety of a broader N rileyi in 1923]

Galls.--Pustulate swellings under the bark, each swelling oval, about 2 x 3 mm, and elevating the bark about 1 mm; usually many galls are confluent, around the twig and along it for a length of 2-12 cm. Larval cells, distinct but inseparable, lie in the wood, near the bark, 1-5 to each pustule, and each about 0.7 mm in diameter. On young twigs of Quercus prinoides.

Range: MA

The galls form in May. 

Neuroterus (Dolichostrophus) rileyi 

GALL. — An irregularly continuous stem swelling. Polythalamous. The swelling rather restricted in size, 10. mm. long or less, raised 5.0 nun. or less above the normal stem, asymmetric on the stem, but often many swellings fused to make a more or less continuous mass 80. mm. long and 12. mm. wide, lying all around the stem; covered with normal bark which is sometimes rather loose and wrinkled. Internally compact woody, the larval cells near the surfaces, with a distinct but wholly inseparable lining. On chestnut oaks (fig. 62). 

RANGE. — Massachusetts to Colorado; possibly transcontinental. 

Neuroterus rileyi variety atripleurae, new variety
agamic form 

GALL. — As described for the species; of medium size, the swelling elevated to 2.5 mm. above the stem. On older twigs of Quercus Prinus. 

RANGE. — Oklahoma: Pawnee. Probably thruout the oak areas of Oklahoma, Arkansas, western Louisiana, and eastern Texas. 

Live adults were in these galls on April 28, 1920, while some had already emerged at that date. This is the agamic generation, and the alternate should be very similar, bisexual, in smaller galls on younger twigs, starting growth in May and emerging in July. 

Neuroterus rileyi variety mutatus, new variety
agamic form 

GALL. — As described for the species, but large, woody, up to 12. mm. in diameter (whole stem) ; on the stems of Quercus Muhlenbergii. 

RANGE. — Texas: Hamilton’s Pool (Travis Co.). Probably confined to an area in Central Texas. 

The occurrence of this insect on a distinct host in a very well-defined faunal area has clearly favored the development of a distinct variety. The gall is so much larger than in other varieties that it somewhat resembles galls of N. batatus.

Neuroterus rileyi variety rileyi
agamic form 

GALL. — As described for the species; large, the swelling elevated above the stem to 3.0 mm. On older twigs of Quercus prinoides. 

RANGE. — Ohio: North Bend (Riley in Bassett). Indiana: (Cook). Illinois: (Beutenmuller) . Missouri: Cadet (Riley in Packard). Iowa; (Cook). Probably confined to a region of the Middle West north of Oklahoma. 

Riley recorded this insect emerging in April and early May, and Cook added that the galls form in late summer, so the insect overwinters in the galls. This is in agreement with the occurrence of other agamic forms in the genus. The alternate generation will be very similar, the insect possibly a little smaller, the galls smaller and on younger twigs, beginning growth in May, with the insects emerging in June or July. 

Neuroterus rileyi variety thompsoni Kinsey
bisexual form 

GALL. — -As described for the species; small, the swelling elevated above the stem, raising the bark to 1.0 mm. On younger twigs of Quercus prinoides.

RANGE. — Massachusetts. 

Thompson stated that these galls form in May. This is a bisexual generation, and adults, if typical for this genus, would develop very quickly, emerging before midsummer. We do not have the emergence date for this material, but it is probably June or early July. The agamic generation would form after mid-summer and emerge early in the following spring, as for variety rileyi.

Neuroterus rileyi

Galls determined by writer as this species were sent to the National Museum December 12, 1920, from Sulphur, Okla., host oak not given. 

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

Neuroterus rileyi

Quercus muehlenbergii, prinus [montana], stellata
Stem galls, woody stem swellings
Local thickenings of the bark in late summer, confluent, one-to-many-celled, covered with normal bark.

[Photo caption]
Q prinus [montana], muehlenbergii, stellata. Confluent, corky puffy swellings along twigs, developing in late summer. Adults emerge the next April and May.