Neuroterus majalis

Quercus alba
Leaf galls, integral
Fleshy, green parenchyma thickening projecting on both sides of leaf in very early spring, 9-11 mm thick.

Quercus muehlenbergii, prinus [montana]
Leaf galls, integral
Fleshy green parenchyma thickening projecting on both sides of leaf when it is hardly half-grown.

[Photo caption]
Fig. 260. On Q alba. Also on Q prinus [montana]. Adults of both sexes out by May 6-11 (DC); June 12 (IL).

Neuroterus irregularis

Quercus chapmani
Leaf galls, integral
Abrupt fleshy thickening of large areas of leaf parenchyma, many-celled, in early spring. Like Fig 260 on Q alba [Neuroterus majalis].

Quercus stellata
Leaf galls, integral
Succulent thickened areas of leaf projecting on both sides in early spring. 9-11 mm thick.

[Photo caption (no photo)]
Gall similar to [Neuroterus majalis]; on Quercus stellata, chapmani. Galls mature before the leaves are full-grown. Adults out May 16-20, 1923; May 24-26, 1924 (DC). A heavy infestation practically defoliates the tree so that it puts forth a new set of leaves. Females were observed ovipositing on the under surface of the leaves and in September the leaves bore numbers of small galls like Neuroterus saltatorius australis Kinsey.

Neuroterus quercusirregularis (Osten Sacken)

Cynips q. irregularis Osten Sacken 1861: 65. Species described from one damaged male (sex not certain) and one gall. Type lost.
Neuroterus irregularis: Ashmead 1885a: 296, 304.
Neuroterus quercusirregularis: Burks 1979: 1074.
Cynips quercus-majalis Bassett 1864: 683. Females, males, galls (types examined). New synonymy.
Neuroterus majalis: Mayr 188 1 : 37.
Neuroterus (Dolichostrophus) irregularis var. majalis: Kinsey 1923: 100

Distribution.-Ontario, New York, Massachusetts, Connecticut, New Jersey, Maryland, Virginia, west to Illinois, Missouri, Oklahoma, Texas, and southward (Beutenmueller 1910). We found this species in North Carolina (on Q. stellata), and in Florida (common, locally abundant, occurs everywhere the host plants grow).

Biology.-Only the bisexual generation is known to induce integral leaf galls on Quercus alba and Q. montana Willd. (Ashmead 1885a, Beutenmueller 19 10, Kinsey 1923, Weld 1959), and Q. chapmanii and Q. stellata (Burks 1979). We frequently found this species on Q. margaretta as well. According to Kinsey (1923), N. quercusirregularis var. albipleurae Kinsey induces galls on Q. breviloba (in Texas only).

The gall is a leaf parenchyma thickening, with the larval cells mostly deeply embedded, and is polythalamous. It is usually elongate, oval, as thick as wide, up to 5.0 mm wide by 15.0 mm long, several galls often fusing, green, very succulent, shriveling considerably upon drying, and the larval cell has a distinct but inseparable layer. The galls are smooth and large when on Q. alba and the pubescence is denser and the galls are smaller when on Q. stellata, Q. margaretta, or Q. chapmanii. Galls usually appear on very young, unfolding leaves, very quickly mature, and develop from April until early June, earlier farther south. Adults emerge from May through July.

Cynips quercus majalis n. sp

QUERCUS ALBA. Flat, green, succulent galls, often of a very irregular outline, and from one-fourth to more than an inch in diameter, the vertical diameter from one-fourth to three-eighths of an inch, growing on the leaves of the white oak, and producing, according to the size, from two or three, to more than a dozen gall-flies. The flies escape from the galls in June, through the upper or under surface. The water that enters the cavities the flies have left causes the galls soon to decay and drop off, but a few change to a dry pith-like substance, and remain on the tree through the summer. These might be taken for a different species, as they generally contain larvae, but having reared a few Spalangia (?) from such galls, I infer they are all parasitic.

This species is closely related to C. q. irregularis O. S. but grows on a different species of oak, and Baron Osten Sacken to whom I sent specimens, thinks it may be specifically distinct from that species, which I have not yet seen. The imperfect condition of his only specimen of C q. irregularis renders a satisfactory comparison impossible, and acting upon his suggestion, I describe it as C. q. majalis n. sp. Several hundred males and females.

Neuroterus irregularis

Galls collected at Clarendon, Va., but a few miles from the type locality of this species, on an isolated tree of Quercus stellata on which fully half of the leaves bore galls, gave adults May 14-20, 1923. At this time the recently emerged flies were seen resting on the leaves by hundreds, the females ovipositing on the under surface. In early September this tree bore thousands of small, nearly spherical, short-pubescent galls recently described as those which yield in March the agamic fly Neuroterus saltatorius australis Kinsey. No other kind of gall was noticed on the tree. In the spring of 1924 the nearly full-grown galls on the leaves were observed again and globular galls collected from the ground beneath still contained larvae indicating that some at least hold over in the galls for two winters before emerging. Adults of irregularis emerged May 24—6, 1924. Another tree some miles away at Takoma Park, Md., bore countless number of these spherical galls which were dropping to the ground in the latter part of September 1923, and this tree was one on which irregularis had been very abundant in the spring. These galls were not observed to jump. In Arlington Cemetery, Va., a tree was seen so heavily infested with irregularis galls in the spring of 1920 that on July 4 the tree was observed to have put forth a new crop of leaves as a result. A sending of fresh galls from Middleburg, Va., yielded 487 adults of which 136 were females and 351 or 72 per cent males.

Neuroterus majalis

The writer has collected galls on Quercus alba at Willow Springs, Evanston (adults emerged June 11-13, 1909), Ravinia, and Fort Sheridan (adults emerging May 30, 1911), IL.; at Miller, Ind.; at Fairfax, S. C. ; at Poplar Bluff, Mo.; at Plummer Island, Md. ; and Washington, D. C. The galls are much more common about Washington than in the Chicago area and are full grown early in May when the young leaves are but 5-6 cm. long. Similar galls were noted on the rock chestnut oak, Q. montana., at Washington and at Falls Church and Alexandria, Va., where adults emerged May 6-11, 1920 and some seemed to be ovipositing on the leaves.

Cynips quercus irregularis n. sp.

QUERCUS OBTUSILOBA [stellata]. Post Oak. Irregular, flattened galls, projecting on both sides of the leaf, yellow, when ripe and dry, and of a substance not unlike soft wood or pith, enclosing several hollow kernels.

Cynips quercus irregularis n. sp.
The sizie of this gall depends on the number of kernels it contains.
One specimen in my possession, about 0.4 long and 0.28 broad, is pierced with 16 holes through which its inmates had escaped; but they may have been small parasites. The average size of these galls is between a quarter of an inch and half an inch in length. Sometimes several of them are packed closely together and separated only by furrows. The color of the galls, when ripe is a light leather-yellow; their substance resembles then the pith of a plant, being softer than wood and still hard enough not to shrink in drying. When examined under a lens of moderate power, the gall appears to be covered with numerous little points or small cones, each bearing a few short hairs on the tip, which under such a magnifying power gives the surface a shaggy appearance. On the 29th of May, when I first discovered these galls, some of them, although yet green, were already pierced with holes. Other galls still contained larvae much later in the season. The only fly obtained from these galls was accidently injured, so that I can give only an incomplete description.

Neuroterus (Dolichostrophus) irregularis bisexual form

GALL. — A thick, leaf blade swelling, involving both surfaces of the leaf, with the larval cells mostly deeply imbedded. Polythalamous. Galls generally elongate, oval, as thick as wide, up to 5. mm. wide by 15. mm. long, several galls often fusing; green, very succulent, shrivelling considerably upon drying; solid, the larval cell with a distinct but inseparable lining, lying mostly below the surface, only rarely evident on the surface. Smooth, naked, and larger when on Quercus alba; very pubescent and smaller when on Quercus stellata (fig. 52).

RANGE. — Ontario to Texas. Probably thruout eastern North America. The galls of this species appear on the very young, un- folding leaves, and very quickly mature, the insects emerg- ing before the leaves are fully expanded. This, of course, is earlier further south, April and May, to early June in New England. The galls become shrivelled and decayed, and only a few remnants will be found later in the summer. Of 430 insects which I have bred for all varieties, 167, or 39 per cent, are males. This is higher than the percentage for the related decipiens, but may show a tendency toward the reduction of the male.

This is clearly the eastern equivalent of Neuroterus decipiens, but the two are distinct species. The present species is closely related to Neuroterus minutus, but irregularis, altho one of its varieties is the type of the subgenus, is certainly an extreme in Dolichostrophus. Irregularis varieties are very poorly defined, and rest in all but one instance on color and size characters, the males being most distinctive. Apparently the eastern third of the United States does not possess the sharply defined faunal areas of the Pacific Coast, and the more uniform geography of the east would lead one to expect this. Further, the eastern oaks are in many instances more closely related than those of the west, and host isolation, in irregularis at any rate, does not appear to have developed distinct insects. These conditions, combined with considerable individual variation, so obscure the group variation that I would hesitate to determine single specimens of the females and sometimes of the males of varieties of this species.

[Kinsey describes several varieties of N irregularis, all of which are still synonyms of the species today. See paper for more information.]

Neuroterus quercusirregularis (Osten Sacken 1861)

Hosts: Quercus chapmanii

[Sexual generation integral leaf gall found in the spring.]