394 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [BuU. 



color, with raised spots, or else entirely brown. These galb are 

 half grown in the autumn and develop so rapidly in the spring 

 that the inmates come out just as the leaves begin to expand. 



N. vesicula Bassett. 



Female : length a little more than 3 mm. ; antennae pale brown 

 at the base changing to dusky brown above, some shades darker 

 throughout than the male antennae, 14- jointed; thorax as in the 

 male, except that there are two parapsidal depressions, which 

 are hardly to be called grooves ; color of wings and venation the 

 same as in the male, legs paler than in the male ; abdomen shin- 

 ing black and not distinctly petiolate. Male: length 3 mm.; 

 head black, the ocelli equidistant, breadth of face considerably 

 less than half the width of one eye as seen from the front ; an- 

 tennae 15-jointed, first and second joints globular, third deeply 

 incised, the remaining ones nearly equal in length, except the very 

 short terminal joint, first joint nearly black at the base, the others 

 yellowish brown but darker toward the tips of antennae; thorax 

 shining black, with microscopic reticulations, but without grooves 

 or lines, surface of the scutel as on the mesothorax, its foveae 

 shallow and indistinct ; wings clear smoky brown, veins dark and 

 heavy, the second transverse vein, when the wings are closed, on 

 a line with the extremity of the abdomen, cubitus reaching to 

 the first transverse vein, areolet present, the radial area appar- 

 ently closed by the somewhat thickened border of the wing ; legs 

 with the coxae and trochanters shining black, changing below to 

 yellowish brown, which is the color of the remaining parts, except 

 the posterior pair which are a little darker than the others espe- 

 cially near the body; abdomen shining black, the first segment 

 forming a petiole, which is enlarged in the middle. 



The gall of this species is a smooth reddish brown vesicle 

 that grows out from the centre of the buds of the white oak and 

 is surrounded at the base by the bud scales. It is sometimes of 

 a pale greenish brown color, its walls are thin, and the larvae 

 contained therein are free, that is, they are not enveloped by 

 larval cells. These galls are partially developed in the autumn 

 and in the following spring they mature so rapidly as to make it 

 possible for the insects to emerge about the time the leaves of 

 the oak begin to expand. 



