Sex. gen. of Neuroterus batatus (Fitch)

Stem galls.
OAK POTATO GALL. Irregularly fusiform, tuber-like stem swellings, 10-40 mm. long by 15 mm. in diameter, deforming the terminal twigs of small trees or sprouts of Q. alba.
In spring at base of the new growth, fleshy, green, glaucous, the adults emerging the latter half of June.

Neuroterus quercus-batatus (Fitch)

Quercus alba
Stem galls, woody stem swellings
Sex. gen. Green, covered with pale blue bloom, 15 mm. in dia., on new growth in June.

[Photo caption]
Fig 125. On Q. alba. Photo also shows the alternating sex. gen. covered with bluish bloom. Adults emerge June 16-25 (IL), May 21 (DC).

[Presumed synonyms]
Quercus breviloba
Stem galls, woody stem swellings
A stem swelling 10 by 30 mm like the summer form of Neuroterus quercus-batatus

Neuroterus quercusbatatus (Fitch)

Cynips Quercus-batatus Fitch 1859: 810. Females and males (type examined).
Neuroterus batata Basset: Ashmead 1885a: 296, 303.
Neuroterus batatus form bisexualis Kinsey 1920: 334.
Neuroterus (Dolichostrophus) batatus var. batatus form bisexualis Kinsey 1923: 4.
Neuroterus quercusbatatus: Burks 1979: 1074.
Cynips noxiosus Bassett 1881: 108. Females, males, galls of both generations (types examined). New synonymy.
Neuroterus noxiosus form vernalis Kinsey 1920: 337. Bisexual generation.

Distribution.-Ontario, Rhode Island, Connecticut west to Illinois, Colorado, south to Florida.

Biology.-Alternate bisexual and unisexual generations are known. Both generations induce stem-swelling galls on Quercus alba L. (Ashmead 1885a, Burks 1979). In Florida, the galls of the bisexual generation also develop on Q. chapmanii and Q. margaretta. The gall is a woody, elongate stem swelling. It is polythalamous, with an irregular shape and a surface that is covered by normal bark, twisted, but in large part cylindrical, tapering gradually to the stem at both ends and up to 20 mm long and 8 mm wide in the bisexual form. Sometimes several galls can more or less fuse, drying brown in bisexual forms, or with a whitish or purplish bloom in unisexual forms [an apparent mistake, copied from Kinsey; these should the other way around]. Internally hard and woody, the tissue is little modified except by the larval cells which are densely packed, each with a distinct but wholly inseparable lining. The bisexual form is on older stems involving the bases of the petioles. The galls of the bisexual generation are less woody, usually on younger twigs, and develop in late spring to early summer. The adults emerge in June and July.

C. q. batatus Fitch.

Quercus alba.

I am satisfied that there are annually two generations of C. q. batatus. The first appears early in May, from galls of the preceding year's growth,--the last late in June, from green galls. I have often found perfect insects in the galls in winter, and have reared flies from them, apparently of the same species reared from the summer galls. Inquilinae in great numbers are produced from the winter galls and few true gall flies, while the reverse is true of the summer form. As many of the summer galls remain green after the flies have left them, and as the tree's annual growth is nearly or quite complete the first of July, it seems probable the June flies oviposit in the galls from which they were produced.

Neuroterus batatus (Fig. 8), pale bluish bloom, corky, many larval cells

Neuroterus batatus (Fitch)

The succulent stem galls of the sexual generation on the new growth were seen [in IL and IN] the adults emerging at Evanston June 16-25, 1913, at Michigan City June 26, 1906.

Oak-potato Gall-fly, Cynips Quercus-batatus, new species.

A large, hard, uneven swelling, three-fourths of an inch thick and twice or thrice as long, resembling a potato in its shape, growing on white oak twigs more distant from their ends than the Oak-tumor.

This gall might be mistaken for a large example of the Elliptic variety of the one first described ["Cynips quercus-arbos"--Callirhytis clavula?], but at each end the swelling arises much more abruptly from the limb, and on all sides of it, whereby the limb is wholly obliterated. Its surface is coated with a glaucous pale blue bloom. Internally it is of a dense corky texture in which are hard woody spots.