56 [October 



1. QUERCUS RUBRA. Red Oak. Large^ smooth, glohular gall on the 

 leaves, filled, when ripe, with a hrown, spongy mass. Diameter about 1.5. 

 Cynips confluens Harris. 



It is described by Dr. Harris (Treatise etc. p. 433). 



These galls are more than one inch, sometimes almost two inches in di- 

 ameter. '• They are green and somewhat pulpy at first, says Dr. Harris, 

 but when ripe, they consist of a thin and brittle shell, of a dirty drab color, 

 enclosing a quantity of brown, spongy matter in the middle of which is a 

 woody kernel about as big as a pea. A single grub lives in the kernel, be- 

 comes a chrysalis in the autumn, when the oak-apple falls from the tree, 

 changes to a fly in the spring and makes its escape out of a small round 

 hole which it gnaws through the kernel and shell. This is probably the 

 usual course, but I have known the gall-fly to come out in October." 



I am more inclined to agree with Dr. Fitch who supposes that there are 

 annually two generations of this fly. They are not rare around Washing- 

 ton, but I have never found them so abundantly as they seem to occur in 

 other localities. On the first of June I found balls of this kind already rip- 

 ened, measuring one inch and a half in diameter, of the usual drab color 

 and somewhat greenish only at its base. One of them, which I opened 

 contained a larva. On the 13th of June another gall was opened, it con- 

 tained the perfect insect, but with wings yet wet and folded and evidently 

 not quite ready to escape. 



On examining the specimens of this gall in my collection, I notice two 

 varieties of it. The one, the surface of which is glossy, occurs on the smooth 

 leaves of the red oak; the other, with a more opaque, almost downy surface, 

 always occured on tomentose leaves. I am unable to tell at present from 

 what kind of oak the latter leaves were taken and hence, whether the gall 

 is a different one or only a variety. I know that the same gall is said to 

 occur on the black oak ( Q. tinctorial ; I found a similar one on the black- 

 jack oak {Q. nigra) and by cutting it open, obtained a gall-fly closely re- 

 sembling C. confluens. But it would require a larger number of specimens 

 to settle the question of their identity or diversity.(*) 



* My manuscript was already presented to the Entomological Society, when I 

 received from Mr. Benj. D. Walsh in Eock Island, 111., two specimens of a gall-fly, 

 which he had reared abundantly from a gall answering exactly Dr. Harris's des- 

 crijjtion of the gall C confluens. He took these specimens for the true C. confluens, 

 in which I cannot agree with him, as the words of Dr. Harris's description (''head 

 and thorax with little pits") do not answer to them. It seems to be therefore a 

 diflerent kind of gall, very like the preceeding, but producing a very different in- 

 sect, as the 9 has 14-jointed, and not 13-jointcd antennte. I add the description of 

 this Cy7ii]>s as follows : 



C. aciculata n. sp. 9 • — Black; antennse 14-jointed, pitch-black: face pubescent. 



