210 HYMENOPTERA. 



In this connection he refers to the discovery of Claus, in 

 1867, of several males of Psyche helix, which had been sup- 

 posed to be parthenogenous, thousands of specimens having 

 been bred by Siebold, all of which were females. 



Baron Osten Sacken (in the Pi'oceedings of the Entomol- 

 ogical Society of Philadelphia, vol. 1, p. 50) says that "a 

 strong proof in confirmation of my assertion is, that in 

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

 ai'e obtained from galls in almost equal numbers ; even 

 the males, not unfrequently, predominate in number (see 

 Ilartig, 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 Cynipes of the oak-apples 

 belong to the genera hitherto supposed to be agamous." 



For an account of the habits and many other interesting 

 points in the biology 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. setninator 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- 

 globnlus 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 will be seen below, that C. qiiercus-futiUs, 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. 



