- Range.—California: Stanford University (I. C. McCracken, Coll.), Three Rivers, and Redding.
- Types.—Thirty-nine females, 11 males, 40 clusters of galls. Holotype female, paratype females, males, and galls in The American Museum of Natural History; paratype adults and galls in Leland Stanford University, the U. S. National Museum, and the author's collection. Labelled Redding, California; April 2, 1920; Kinsey collector.
This species is very abundant early in the spring; the galls are very succulent and the insects mature quickly after the unfolding of the leaves. There must be, therefore, another generation in the year, probably agamic. Insects were emerging at Three Rivers on March 22, but some hundred miles farther north, at Redding, adults did not emerge until some time after collection of the galls on April .2. Of 93 adults of my collection, only 14 are males, not the usual ratio for bisexual generations of this genus. Material of this species is in several collections labelled Neuroterus pacificus Beutenmüller, but this is obviously not that species.
Neuroterus engelmanni, new species
Plate XXIV, Figure 4
Female.—Entirely piceous black; antennae brown, straw-yellow basally; wingveins light brown but cubitus and discoideus almost colorless; length averaging under 1.0 mm. Head: Somewhat wider than thorax, broadened behind eyes; piceous black, mandibles rufous brown; microscopically reticulate, the front smooth and naked, hairy about the mouth. Antennæ brown, straw-yellow basally, the third segment very much the longest and most slender. Thorax: Piceous black, microscopically reticulate, devoid of thoracic grooves, naked of hairs, not shrivelling as much as in many species of this genus; scutellum elongate cushion-shaped, an arcuate, smoother furrow at the base. Abdomen: Entirely piceous black, naked of hairs; finely but not long pedicellate; angulate-oval in shape, not as triangulate and shrivelled as in many species of the genus. Legs: Piceous yellow, darkest basally, brown to straw-brown toward the tips of tarsi, but the tips dark; finely pubescent. Wings: Clear, long-ciliate on margins; veins brown, cubitus and discoideus fine and light in color; areolet of moderate size; radial cell moderately long, narrow, open; cubitus reaching the basalis (though hardly discernible there) nearly at the point of union of the basalis with the discoideus; first abscissa of the radius about arcuate. Length: 0.7-1.2 mm.
- Galls (Pl. XXIV, Fig. 4).—Pustulate swellings embedded in the leaf-tissue; monothalamous, but often several galls confluent; about circular, averaging 1.2 mm. in diameter. The surface of the leaf not modified, the under surface somewhat distended, the upper surface less so but very evidently swollen; thin-walled, hollow. On leaves of Quercus Engelmannii.
- Range.—California: Alpine, Fallbrook.
- Types.—Eleven females, and a great many galls. Holotype female, paratype females, and galls in the collections of The American Museum of Natural History; paratype females and galls at Leland Stanford University, and with the author;
