196 DIPTERA OF NORTH AMERICA. 



a purplish-black ring, on the leaves of Solidago; under each spot, 

 inside of the leaf, several larvae. I found them commonly in Au- 

 gust, and observed that the hollow space within the leaf was fre- 

 quently filled with a hard, black substance, not unlike charcoal. 



12. G. racemicola, n.- sp. Bud-shaped gall among the racemes 

 of Solidago. It has about 0.1 in diameter, is green, and looks 

 exactly like a bud, but is easily distinguished from the buds of 

 Solidago by its stout, rounded form. Each gall contains a single 

 reddish larva. Not rare in September. 



13. G. vaccinii, n. sp. Gall on the leaf of Vaccinium (or Gay- 

 lussacia ?), in the shape of a cock's comb, I found near Wash- 

 ington, in October, one single leaf with two galls of this kind, 

 arising from the central rib. The largest of the galls was about 

 0.15 high and 0.2 broad about the middle. They were green, and 

 resembled pretty much a cock's comb, or, still better, an oyster, 

 fastened by its hinge. After having been kept for some time on 

 moist sand, both burst open exactly like the valves of a shell, and 

 a reddish larva escaped from each. Both wandered for some days 

 in the bottle in which I kept them, and inclosed themselves after- 

 wards in delicate semitransparent cocoons, formed above the sur- 

 face of the sand, between some chips of paper which I had provided 

 for them. Unfortunately, both died without undergoing their final 

 transformation. 



14. C. pini inopis, n. sp. Resinous cocoon on the leaves of 

 the scrub pine (Pinus inops). Similar cocoons have been observed 

 on the European pine, and described a century ago by Degeer. 

 Ratzeburg, in his Forst-Insecten, describes and figures the same 

 cocoon, as well as the larva and the perfect insect, G. pini Deg.* 

 Dnfour (in the Ann. Soc. Entomol. de France, 1838, p. 293) gives 

 an account of a Gecidomyia with precisely similar habits, which he 

 observed on the South European pine (Pinus marilima), and which 

 he called C. pini maritimtz. 



The larva producing these cocoons is remarkable for two rows 

 of oblong, pointed, fleshy protuberances along its back, and & 

 similar row on each side. (See Ratzeburg, Forst-Insecten, III, 

 Tab. x, f. 14, L.) Early in April I saw some of these larvue 

 emerge from a small hollow between two terminal buds, where 

 they had probably spent the winter, and crawl along the leaves, 



* See the same figures of cocoon and larva in Wiegm. Archie, etc., 

 vol. VII, p. 233. 



