No. 22.] HYMENOPTERA OF CONNECTICUT. 399 



The gall of this species consists of an oval cell occurring 

 either singly or in clusters of from two to eight on the under side 

 of the leaves of Quercus bicolor. The galls are sessile and situ- 

 ated on the midrib and principal veins, and usually lie in a posi- 

 tion nearly parallel to the surface of the leaf. They are at 

 first covered with short woolly hairs, but when ripe become more 

 or less denuded. They measure 2.5 mm. in length and 1.2 mm. 

 in diameter and resemble very closely the cocoons of some species 

 of Microgaster. 



New Canaan, 17 September, 1915 (B. H. W.). 



°D. polita Bassett. Polished Oak Gall. 



Female : length nearly 3 mm. ; head apparently black, but of a 

 very dark reddish brown when seen in certain lights, cheeks 

 somewhat lighter than the other parts, vertex reticulate, antennae 

 black, 14-jointed, the first joint club-shaped, the second oval or 

 ovate, the third as long as the first two combined, the fourth 

 one-fourth shorter than the third, the remaining joints except the 

 apical one subequal, the last joint a little longer than the preced- 

 ing; thorax black and smooth, with two parapsidal grooves, 

 between which are two parallel depressions that reach from the 

 pronotum two-thirds of the distance to the scutel ; few scattered 

 hairs on the thorax, the highly polished pleurae bordered with 

 scattered white hairs, scutel finely wrinkled and rounded 

 posteriorly and projecting over the metathorax, its fovese widely 

 separated and shining; legs very dark reddish brown, a little 

 lighter at the sutures; wings hyaline, cubitus pale, radial area 

 open ; abdomen black and polished, its pedicel more than half as 

 long as broad, sheath of the ovipositor slightly projecting and 

 tipped with a few long yellowish hairs. 



The galls are round, monothalamous, common in midsummer 

 on both surfaces of the leaves of Quercus obtusiloba, at or near 

 the summit of the young shoots, with from one to fifteen or 

 twenty on a single leaf. They range in size from 6 to 18 mm. in 

 diameter, and when fully matured are of a paler shade of green 

 than the leaf on which they have grown, except where exposed to 

 sunlight, in which case they become red or brown. The point 

 of attachment is so small that upon removing them there is hardly 

 any trace left of their having been attached to the leaf stem. The 

 shell of the gall is, when dry, very thin and brittle, and the single 



