shallow but distinct lateral grooves extending almost parallel to the parapsides three-quarters of the way to the point where the parapsides meet the pronotum; median groove lost in the deep rugosities of the mesonotum; scutellum rather elongate, deeply rugose, hairy, with a very broad, rather deep depression at the base, with conspicuous, divergent ridges, but hardly defining distinct foveæ; mesopleuræ shallowly punctate, with long, appressed, yellowish hairs. Abdomen: reddish or yellowish red, brighter basally, smooth, with a few hairs at the sides of the second and on the edge of the third and following segments, the second segment somewhat projected dorsally to two-thirds the length of the abdomen; ovipositor sheaths short. Legs: reddish brown to reddish piceous, shallowly punctate and entirely hairy, the tarsal claws toothed. Wings: one-third again as long as the whole body, clear, regularly covered with short, dark hairs; all of the veins brown, the subcosta and radius the heaviest; areolet fairly large; cubitus not extending to the basal vein; radial cell open; the first abscissa of the radius curved very nearly at the midpoint to form an angle which is only a little greater than a right angle. Length: 2.0–3.2 mm.
Gall.—A light grayish brown, rather regular swelling (Figs. 14 to 16) around small twigs, resembling a baked potato. Polythalamous, a single gall containing fifty or more larval cells. Usually a single, regular mass, rarely somewhat convoluted as though several portions had been fused; varying from a spherical to ovoid shape, usually somewhat concave where the twig enters the gall; 4.5×6.0 cm. or less in diameter; matted, light brownish gray in color, resembling the skin of a baked potato, with scattered flakes or patches of a loosened, dark brown, "burnt" skin. The whole interior is hard, compact-granular, with very little solid woody fibre; the larval cells average 2.5×4.0 mm., formed of a layer distinct from but closely embedded in the surrounding tissue, the cells scattered irregularly throughout the gall, but more abundantly nearer the center. Surrounding and surmounting the young twigs (preventing their further growth) of Quercus sp.
Range.—Mexico: San Luis, Potosi (Schaffner, Palmer Coll.).
Cotypes.—Thirty-seven female and ten gall cotypes in The American Museum of Natural History, the Museum of Comparative Zoology, and in the author's collection. The insects were cut from one of the galls collected by Schaffner in 1880.The same species was collected in 1878 in the same locality by Dr. Edward Palmer, and adults emerged from these galls in the stummer of 1879.
This belongs to a group of several species from Mexico which are similar in coloring and general characters of pubescence, sculpture, wing venation, etc., and which produce, as far as known, similar galls which are large, woody swellings of twigs. Inasmuch as these species are so confusingly similar, it seems worth giving the following key for distinguishing them.
Woody Galls, Mexican Species of Andricus
| 1. | Head or thorax or both with some reddish coloring, abdomen without any black; parapsidal grooves complete | 2. |
| Head and thorax entirely black, ovipositor sheaths black; parapsidal grooves obliterated posteriorly | A. championi Ashmead. |
