Page:The Gall Wasp Genus Cynips.pdf/167

Rh both sexes; the abdomen of the male petiolate, that of the female subsessile. Length 2.5 mm.

Wasp: Head black, feebly, very finely and deeply punctate, scatteringly hairy about the eyes, the mandibles rufous-yellow, the palps pale in color. The 15-segmented antennae are feebly hairy, dark brown, the first four segments in the female and the first two in the male somewhat lighter in color, the tip of the second and the very base of the third golden brown. The mesonotum smooth, shining, divided by two deep grooves into three distinct parts. These grooves are only a little shallower anteriorly than posteriorly. It is only at the base and about the grooves that there is a feeble punctation, the rest of the surface appearing smooth even with high magnification. The scutellum is finely rugose, black, sometimes brown at the tip, with a fine gray pubescence, the base always with a shallow, smooth and shining foveal grove. The prothorax and metathorax are rugose laterally, the mesopleura being smooth and shining. The tegulae and hypopygial spine are rufous. The legs are largely bright golden rufous, only the coxae, the trochanters of the front and middle pairs of legs, and the bases [?] of the femora [?] brownish piceous. The abdomen of the male is short petiolate, the petiole light brown. The wings are only faintly obscured with hairs, the veins being dull brown, slightly yellowish, the anal vein having a clouded spot at the mid-point. The abdomen of the female is almost sessile. Length 2.5 mm.

Gall: The small, graceful galls, 3 to 4 mm. in length, appear in May when the oak leaves first unfold, occurring on the edges of the leaves, developing either from the main veins or the lateral veins. In form the gall is either cylindrical, flaring at the tip and the base, or bluntly tipped and cone-shaped with the base slightly constricted and the middle thickest. The color is at first a dull blue-green, becoming yellowish-green or slightly reddish. What makes the gall especially attractive is the nature of the epidermis which appears warty or roughened with aggregations of small, perfectly clear vesicles which are filled with liquid; between these vesicles are a few stray hairs. The fleshy, succulent wall of the gall encloses a cylindrical larval cell.

TYPES.—5 insects in the Vienna Museum (acc. F. Maidl in litt.). The Schlechtendal material from Halle, near Berlin, and Zwickau in Germany.

The present descriptions are based on the published descriptions cited in the bibliography, and on four insects I have from Thüringen, Germany.

PARASITES—Torymus abdominalis Boheman. Emerges the same June (acc. Wachtl 1876). Decatoma sp. Emerges the same June (acc. Wachtl 1876). Eurytoma sp. Emerges in June (acc. Wachtl 1876).

The very attractive, leaf galls of this bisexual form of divisa are quite distinct in shape from the usually adventitious bud galls of the bisexual forms known for other European