686 [1>ECE>IBF,R 



black shining, second segment longest, separated from the third by a connate 

 suture, third with raicroscopio punctation. Sheath of the ovipositor not turned 

 up nearly so much as in G. q. similis, to which species it is closely related. 

 Wings hyaline, sub-costal, first and second transverse veins pale brown, others 

 colorless ; lower part of the cubitus obsolete; areolet present: radial area open. 

 Length .12. 



Nine specimens. 



I have a single male gall fly reared from the same galls, but it differs 

 so much from the female that I am inclined to think it belongs to a 

 different species. The thorax is quite smooth and shining, with a few 

 short, scattering hairs, and only two longitudinal lines that closely con- 

 verge at the scutellum. The venation of the wings is like that of the 

 female described above, and is unquestionably that of a true gall-fly. 

 The antenna? light dusky brown. 15-jointed ; legs dark shining brown, 

 nearly black, paler at the joints. 



Though the galls are very much alike, the venation of the wings, 

 the pleurae, and several other points of difference mark it as a distinct 

 species from C q. similis. Dr. Fitch has figured the gall of his C. q. 

 tuber which he found "quite common particularly upon the soft and 

 tender limbs of young (white oak) trees" (N. Y. Rep., Vol. 2d, No. 

 309). He describes (1. c. No. 310) the galls of C. q. arbos as "swellings 

 similar to that above described, growing on the tips of the limbs of 

 aged and large white oak trees." 



My galls, which are probably identical with his G. q. tuber, were 

 gathered from low, shrubby white oak bushes, though I have often 

 Been precisely similar ones on large trees. Dr. Fitch's descriptions of 

 the flies from (J. q. tuber or O. q. arbos will apply, so far as they go, to 

 either the gall flies, or to the guest flies as the inquilinje are termed by 

 Mr. Walsh. For the reasons that follow, I am led to think that the 

 species he described under the above names are both inquilinious 

 species. 



1st. My galls were gathered about the 20th of June, and were then 

 green and soft like the wood of the young shoots on which they grew. 

 The insects were then in the pupa state, and the imago came out early 

 in July. The gall from which Dr. Fitch's G. q. arbos was reared was 

 found in March, and were of the preceding year's growth, as were also 

 those of G. q. tuber, if we may judge from his description of the color 



