Page:New Pacific Coast Cynipidæ (Hymenoptera).pdf/16

 galls in the U. S. National Museum. All the adults are imperfect. Labelled Fallbrook, California; February 26, 1920; Kinsey collector.

The galls were very abundant on the few trees on which they were found. On February 24 and 26 they contained only larvæ. Of the two or three thousand insects bred from one of the lots of galls, only eleven gall-makers were recovered, the other insects being parasites. The galls closely resemble Neuroterus niger Gillette which occurs on Quercus macrocarpæ, N. perminimus Bassett on Q. alba, N. papillosus Beutenmüller on Q. bicolor, and several other species which I shall describe from other species of oaks. The insects of these species show evident relationships morphologically, and it is of considerable significance to find the galls (an expression of the physiology of the insect!) similarly related. These species are certainly distinct, but it may be desirable at some time to label them varieties. Such "host varieties" are biologically important because of the material they may offer for experimental work on the possible effect of environment (the host) on the insect.

Neuroterus varians, new species Plate XXIV, Figures 17 and 18

—Entirely black, including the legs and the antennæ for the most part; abdomen extending ventrally as far as or farther than dorsally; areolet of a moderate size to closed; length varies, 1.0-1.8 mm. {{smallcaps|Head: As wide or wider than the thorax, protruding slightly back of the eyes; black, light rufous brown around the mouth and on the mouth-parts; only microscopically coriaceous; practically naked of hairs. Antennae piceous black, the second and third segments in part lighter piceous; hardly hairy; with 13 segments, third most slender and longest but not considerably longer than fourth, last segment not much longer than the preceding. {{Smallcaps|Thorax:}} Entirely black; mesothorax smooth, shining, naked of hairs, entirely without the usual grooves and lines; scutellum smooth, shining, naked, with a smooth, arcuate furrow at the base; pronotum smooth, very finely punctate and hairy at the sides, not very evidently so; mesopleuræ practically smooth, shining and naked. {{Smallcaps|Abdomen:}} Black, piceous ventro-apically; smooth, naked; usually protruding as far or farther ventrally than dorsally, as high or higher than long. {{Smallcaps|Legs:}} Black (piceous in small individuals), light piceous yellow at the joints and on the tarsi, tips of tarsi dark; shining, smooth except for minute punctures, minutely hairy; tarsal claws simple. {{Smallcaps|Wings:}} Long, clear, set with very fine hairs, long-ciliate on the hind margins, hardly ciliate on the anterior margins; veins light brown; areolet of moderate size (small or closed in small individuals); cubitus continuous to the basalis; radial cell open, not as long and narrow as usual in this genus; first abscissa of the radius sharply angulate, very slightly infuscate where it leaves the subcosta. LENGTH: 1.5-1.8 mm. (individuals vary, down to 1.0 mm.).


 * {{Smallcaps|Galls}} (Pl. XXIV, Figs. 17,18).—Short, blunt, irregular stem swellings. Polythalamous. Distorted lateral stems, 5.-12. mm. in diameter, 6.-35. mm. long, very rough, covered with bark of natural color; very irregular in shape, involving distorted buds, petioles, or leaves. Internally the larval cells are closely compacted, located mostly