330 EXTOMOLOGTCAL NEWS [Xov.,'l8 



Fore tibiae brown, femora darker, middle and hind legs pitchy 

 brov^n with the knees paler. 



Wings hyaline, veins delicate brown. Radial area closed. Cubitus 

 exceedingly faint and not extending to the first cross-vein. Areolet 

 large. 



Length, 2.75 to 3.25 mm. 



Gall. — On the under sides of the leaves of post oak {Quercus minor) 

 in clusters from about 4-40 individuals closely packed together, on the 

 mid-rib and lateral veins. September to November. Monothalamous. 

 Green, sometimes tinged with red. Elongate, rounded at the sides, 

 narrow at the point of attachment and concave at the apex with a 

 small central nipple. Outside it is rather densely covered with small 

 pustules. When young, the gall is almost solid, but as it grows older 

 the larval chamber gradually occupies the entire interior. After it 

 drops to the ground, late in the fall, the gall gradually changes its 

 shape to almost globular ( berry-like j with the concave apex flat- 

 tened and the surrounding rim less prominent. The crystal-like pus- 

 tules change, the gall becoming evenly rugose. The point of attach- 

 ment becomes long, narrow and sharply pointed. The entire inside be- 

 comes hollow with the outer wall thin and brittle. 



Length, 2.50 to 5 mm. ; width, 2 to 4 mm. ; length of clusters, 5 to 

 35 mm- 



Habitat: Westchester. New York City. 



Type : female in the writer's collection. 



My observations on the galls were made from at least 500 

 clusters. At first I considered it to be that of Zopheroteras 

 vaccinii Ashm., which it resembles when immature. But the 

 flies are different, the female of vaccinii being apterous. The 

 gall of A. impositus when mature resembles somewhat 

 those of Cynips dimorplnis and C. 7-acciniifonnis. My galls 

 were collected during September and until November ist, 191 5, 

 but they evidently also occur earlier in the season, because 

 some of the flies emerged in June and July and others in 

 September, 19 16. But the majority remained over until 19 17. 

 the flies emerging indoors in January and February. My 

 specimens were collected on a small rocky elevation in a 

 swamp, close to the Bronx River, near Westchester, Xew 

 York City. This locality is gradually being filled in for streets 

 and other improvement and soon will become extinct. I have 

 also taken the gall at Lakehurst, New Jersey, and it probably 

 will be found in other places where Oucrciis minor grows. 



