320 HENRY SHIMER, M. D. 



spring asceud the trunk. As spring passes into summer, I observe 

 many leaves entirely covered with these galls, so that the leaf is dw;irfed. 

 curls up and sometimes drops off; a thousand or more galls are some- 

 times found on a single leaf. In June I observed in the galls numer- 

 ous whitish, translucent eggs, and larvai in abundance; these latter are 

 falciform and very sluggish and without much observable motion. 

 After about two weeks, I saw them in great numbers, crawling abmit 

 on the leaves, having left the galls to ascend to the body, doubtless for 

 the purpose of establishing new galls; one fine warm days, thousan<ls 

 may be seen on one leaf. Soii^e spider webs on the under side of the 

 leaves serve as traps for these creatures, where they accumulate in sucli 

 numbers as to give the web a pale reddish color, although the indi- 

 vidual acarians are undistinguishable to the naked eye. The galls con- 

 tinue during the summer, but later many of them become black and 

 drii and vcri/ feic of the green ones then contain inhalnta)its. 



ACARUS, Linn. 



Acarus aceris, n. sp. — Imago. Thorax yellowish-brown, legs inclined to same 

 color ; a grayish central line on the back, on each side of which there is some- 

 times another line of like color; a number of whitish hairs about as long as the 

 legs are scattered over the body; tarsi 3-jointed, with two claws and a number 

 of hairs ; head rounded, depressed, grey, forehead slightly emarginate. Lengtli 

 of body 0.13 inch; to end of extended forelegs, .02 inch. 



Pupa of various colors, from pale greenish-grey to blackish, with a few eom- 

 jiaratively long hairs; legs greyish, translucent; head and anterior part of body 

 pale. The very young larvae are nearly white. 



Eggs globular, milk-white, 0.04 inch in diameter, placed on under side of the 

 leaf. 



In June these acarians were quite numerous on the underside of the 

 leaves, and a number of their moulted skins were observed, principally 

 along the veins of the leaf. I sometimes find this species on the 

 same leaves in company with Vasates quadrlpedes. From observing 

 their motions, and from often finding them without any other probable 

 food, I concluded that they feed on the sap. The larvae of Chrysojxt 

 and also of some species of CoccinellidiB have been observed feeding 

 upon these acarians, and no doubt devour many of the larvas of Ceci- 

 domi/ia acen'x (Trans. Am. Eut. Soc. i. p. 281) which were abundant on 

 the leaves. 



JJt. CarrolL I/limnx, April 1st, 1869. 



