1801.] 71 



They can be recognized immediately l>y their club-shaped form, the ves- 

 tiges of" the leaves (usually three), broken oft" from their tip and the flat- 

 tened, uneven surface between these vestiges, with the round hole, through 

 which the insect escaped, generally in the centre. If cut lengthways in 

 two, an elongated cavity is found just below this hole, and under this, a 

 second, smaller, more rounded cavity. The latter contains the larva. 



Sometimes there are two cavities of the latter kind and consequently 

 two larvae occur in the same gall. On the 4tli of July I found a pupa in 

 an advanced state of ripeness in one of these galls; in the adjoining cell 

 however was still a larva. I did not succeed in obtaining the gall-fly; in- 

 stead of it, one of the specimens gave me Ilijdnocera vertlraUa Say, a col- 

 eopteron, living, as it seems, parasitically on oak-galls, as I obtained it al- 

 so from the oak-bullet gall ( G. que.rcus tuber) of Dr. Fitch. 



This gall is very common around Washington. Is it the gall of Gi/nijjs 

 quercus arbos Fitch (Reports, Vol. II, No. 310)? From the gall of G. 

 quercus tuber Fitch it is easily distinguished by its more constant form, 

 its more uniformly woody consistency and the absence of the seed-like 

 shells, containing the larva. 



I have found similar swellings on other kinds of oaks also. 



^!^'- 



26. Quercus alba. White Oak. " Large, hard, uneven noelh'ng, 

 three-quarters of an inch thick and twice or thrice as long, resembling a 

 potato in its shajje, growing on white oak twigs, more distant from their 

 ends than the oak tumor." (Dr. Fitch, Reports, No. II, No. 311.) Cynips 



QUERCUS BATATUS Fitch. 



" Its surface is coated with a glaucous, pale blue bloom, internally it is 

 of a dense, corky texture in which are hard, woody spots." (ibid.) 



" The fly has the basal joints of the antennae and its legs dull pale yel- 

 low, its thighs and hind shanks black and its middle shanks often dusky, 

 the antennae of the female with thirteen joints and the length of this sex 

 0.09." (ibid.) 



I have found near Washington a single gall answering this description, 

 but did not succeed in obtaining the insect. 



o 



27. Quercus alba. White Oak. Swelling of the small limbs or 

 twigs. (Dr. Fitch, Reports, Vol. II, No. 309.) Cynips quercus tuber 

 Fitch. 



These galls are easily distinguished from the club-shaped galls by their 

 inside. " On cutting into these galls, says Dr. Fitch, the small limb on 

 which they grow is found to have its wood thickened or swollen, and over 

 it, forming the chief bulk of the tumor, is a corky substance of a yellow- 

 ish-brown or snuff" color, between which and the wood are several small 



