220 Baron Osten Sacken on two new JV. A. Gecidomytae. 



indicated by a grayish efflorescence and their intervals by two black lines, 

 which bear a longitudinal row of pale hairs; in the female, the underside of 

 the thorax is reddish: feet gray, with a whitish lustre: wings gray, darker 

 along the costal vein ; neuration like fig. 1 in Monogr. etc. I. p. 174. Abdomen 

 blackish, with pale hairs ; in the female it is red, each segment bearing a 

 transverse black stripe on the back. Length about 0.065 of an inch. This 

 description was drawn from mature living specimens. 



The immature specimens had a reddish thorax, pale brownish above, 

 without indication of stripes; a black fringe of short hairs or scales 

 along the anterior margin of the mesothorax was very apparent in the 

 male, less distinct in the female. 



Some time ago Mr. Win. Couper in Quebeck, sent me some speci- 

 mens of a very pretty gall, which he discovered on Spiraea salicifolia 

 and which I take occasion to describe here. 



This gall, the as yet unknown insect of which I propose to call 

 Cecid. salicifolise has, like the preceding gall, the shape of a pod, 

 firmed by the folding of the leaf along the midvein, and the bulgiug 

 out of the sac thus formed, the outer margin of which is closely sol- 

 dered. The largest of the pods which I have before me is a little 

 over half an inch long and absorbs the whole leaf, except a narrow 

 margin, projecting above the seam of the pod; the smaller pods oc- 

 cupy only a portion of the the leaf. Although the galls were dry, 

 when they reached me, the larva? in them were still alive. 



I found a similar gall in Nahant in August, 1864, quite abundantly 

 on Spiraea tomentosa. The young terminal leaves of this plant were 

 folded up so as to assume a pod-like appearance and enclosed larva? of 

 Gecidomyia, but I am not certain whether these larva? belong to the 

 same species as that which deforms Spiraea salicifolia in Canada. 



Among the European Gecidomytae only one is known to affect the 

 genus Spiraea; it is Ccc. ulmariae Bremi, which produces wartlike 

 galls on the leaves of Spiraea ulmaria. (Winnertz, Linn. Entom. 

 Vol. VIII. p. 240.) 



