450 THE ENTOMOLOGIST. 



galls needs no further proof than I now give. The insect 

 C. q.-operalor is distinguished from all our other species by 

 the projection of the ovipositor above the dorsum. In this 

 respect it resembles the several species of guest gall-flies that 

 infest almost all our species of galls. It has, however, the 

 neuration of the true gall-flies. In size my insects are 

 considerably larger than C. q.-operator, but in form, colour, 

 neuration of the wings, and, above all, in the peculiar form 

 and position of the sheath of the ovipositor, they are like this 

 species. Few will doubt their identity; but to make "assu- 

 rance doubly sure" I hope some one will be so fortunate as 

 to raise gall-flies from these acorn-galls, when a comparison 

 with mine will settle the question whether this particular 

 species (C. q.-operator) is double-brooded or not. 1 wish (if 

 my article is not already too long) to state a few other facts, 

 and to show their bearing upon the history of these interest- 

 ing insects. 



" There stands not far from my house a small oak-tree, 

 Q. bicolor, which is almost ruined by the ravages of a species 

 of gall-fly, which closely resembles, and may be identical 

 with, C. q.-botatus, Bassett. Every summer the leaves of 

 this tree are so injured by the galls that scarcely one perfect 

 one can be found on the tree. The petioles and mid-veins 

 are enlarged to the size of one's finger, and the blade shrivels 

 up or remains undeveloped, and each gall contains a large 

 number of insects which come out in June. I have reared 

 many thousands of these gall-flies, and find them of both 

 sexes — about equally divided. 



"Late in the summer another form of gall appears, this 

 lime on the ends of the small branches, and the insects 

 remain in these, in the imago, through the winter. I have 

 reared not less than fifteen thousand of these gall-flies, and 

 all are females, and they cannot be distinguished from the 

 summer brood, except that they are a very little larger. The 

 flies of C. q.-futilis, o.s., are of both sexes; but among the 

 considerable number found ovipositing in the buds of the 

 white oak, and which, I have no doubt, produce the galls of 

 C. q.-futilis, there are no males, and the females are con- 

 siderably larger than the summer brood. And again, in my 

 last discovery the flies are all females, but larger than the 

 females of C. q.-operator, though they have the structural 

 peculiarities of that species. 



