104 Bulletin of the Brooklyn Entomological Society Vol. Vlll 



or channel at the base. Abdomen well rounded dorsally, the 

 large second segment smooth, the following segments micro- 

 scopically punctate. At the base of the second segment are a 

 few minute whitish hairs. Sheath of ovipositor black, stout 

 and extending upward but not beyond the anal segment. 

 Wings pale, hyaline, cross and basal veins heavy, yellowish 

 brown and very slightly clouded with the same color, outer 

 veins faint ; radial area broad and open at the costal margin ; 

 second cross-vein bluntly angulate or rounded outwardly; 

 areolet very small ; cubitus fine and not extending to the cross- 

 vein. Length 2.50 to 3.25 mm. 



Gall. — In the cups of acorns of swamp white oak (Qi^ercus 

 platanoides) , burr oak (Q. macrocarpa) , dwarf chestnut oak 

 (Q. prinoides), chestnut oak (Q. prinus), and probably other 

 trees belonging to the white oak group. Monothalamous. The 

 gall is formed in a cavity, causing more or less bulging and 

 swelling of the acorn cup. It is an elongate body averaging 

 when well developed 5 mm. long and not quite half as wide. 

 The sides are sometimes parallel, but more often slightly 

 bulging or sometimes longitudinally ribbed or smooth ; whitish 

 green, yellowish, often with a roseate tinge. The base is 

 truncate and covered with a whitish down. The crown is flat- 

 tened or slightly concave with a small central conical nipple. 

 The mouth of the cavity in the acorn cup is either strongly 

 fimbricated or simple, according to the nature of the cup scales, 

 and thus either concealing the gall or exposing a large part of 

 it. The larva lies in a cell near the top of the gall. Sometimes 

 the galls deform the acorns. 



Habitat: N. Y., Penn., N. J., 111., Ohio, Mo., Conn. 



Many years ago the late C. V. Riley gave me a specimen of a 

 gall-fly which he said he had raised from the oak-pip gall in the 

 acorn cups. But the species was never described by him, ex- 

 cept from the gall which he termed Cynip quercus glandulus. 

 While collecting in the pine barrens at Lakehurst, N. J., very 

 early in May, I took a number of female gall-flies on the twigs 

 of the dwarf chestnut oak, presumably ovipositing in young 

 acorns. My specimens agree in all particulars with the one 

 given to me by him, and are described above together with his 

 as being the producers of the oak-pip galls. The ripe and well 

 developed gall falls out of its cavity to the ground, where the 



