210 HYMENOPTERA. 



shaped gall is the male of the Cynips of the oak-apple, and if 

 it is shown, by further observation, that in the genera, supposed 

 to be agamous, by Hartig, the males produced from galls are 

 different from those of the females, then it will be plain how 

 28,000 galls of the same kind could give 10,000 females and 

 not a single male. 



"A strong proof in confirmation of my assertion is, that in 

 those genera, the males of which are known, both sexes are 

 obtained from galls in almost equal numbers ; even the males, 

 not unfrequently, predominate in number (see Hartig, 1. c. iv, 

 399). Now the gall-flies, reared by me from the oak-apple, 

 were all females. Dr. Fitch, also, had only females ; and Mr. 

 B. D. Walsh, at Rock Island, Illinois, reared (from oak-apples 

 of a different kind) from thirty-five to forty females, without a 

 single male. This leads to the conclusion that the Cynips of 

 the oak-apples belongs to the genera hitherto supposed to be 

 agamous." 



For an account of the habits and many other interesting 

 points in the biolog}^ of these interesting insects, we further 

 quote Baron Osten Sacken. ' ' Most of the gall-flies always attack 

 the same kind of oak ; thus, the gall of C. seminator Harris, 

 is always found on the white oak ; C. tubicola Osten Sacken on 

 the post oak, etc. Still, some galls of the same form occur on 

 different oaks ; a gall closely resembling that of C. quercus- 

 globulus Fitch, of the white oak, occurs also on the post oak, 

 and the swamp chestnut oak ; a gall very similar to the com- 

 mon oak-apple of the red oak occurs on the black-jack oak, etc. 

 Are such galls identical, that is, are they produced by a gall-fly 

 of the same kind? I have not been able to investigate this 

 question sufficiently. Again, if the same gall-fly attacks dif- 

 ferent oaks, may it not, in some cases, produce a slightly differ- 

 ent gall ? It w r ill be seen below, that C. quercus-futilis, from a 

 leaf-gall on the white oak, is very like C. quercus-papillata from 

 a leaf-gall on the swamp-chestnut oak. I could not perceive 

 any difference, except a very slight one in the coloring of the 

 feet. Both gall-flies may belong to the same species, and 

 although the galls are somewhat different, they are in some 

 respects analogous, and might be the produce of the same gall- 

 fly on two different trees. 



