Mar., 1909.] ROHWER : CRYTOCAMPUS IN BOREAL NORTH AMERICA. 7 



THE SAWFLY GENUS CRYTOCAMPUS IN 

 BOREAL NORTH AMERICA. 



By S. a. Rohwer, 

 Boulder, Colo. 



This paper is the result of my studies on the Nematid genus 

 Crypiocampus (= E/ii/ra). The species of this genus resemble each 

 other in the color very much. For example, the males of behbianct, 

 macgillivrayi, salicis-ovum, salicis-nodus and propinqmis cannot be 

 separated by any reliable color character, yet they are all very distinct. 

 This being the case, the old descriptions, which deal almost entirely 

 with color, are of very little value. I have found the shape of the 

 sheath and the sculpturing of the head to be constant within each 

 species, and very valuable in separating the various species. The fol- 

 lowing is an explanation of the terms used in this paper. Many of 

 them are used in Mr. C. I>. Marlatt's most valuable work on the 

 Nematinte of North America [Tech. Ser. 3, U. S. Dept. Ag., 1896]. 

 Middle fovea = the fovea between the bases of the antennae. 

 Middle carina = the carina between the bases of the antenncC, below 



the middle fovea. This is sometimes wanting and is 



of little value in this genus. 

 Antennal foveae = the foveae around the bases of the antennae. 

 Frontal crest = the part of the front between the bases of the antennae, 



above the middle fovea. This is best seen from 



above. 

 Ocellar basin = the basin around the lower ocellus. 

 Interocellar furrow = the transverse furrow behind the lateral ocelli. 

 Lateral ocellar furrow = the longitudinal furrows which usually extend 



from the occiput to the antennal foveae. 

 The larvae of all the known American species make galls upon the 

 twigs of some species of willow. It seems highly probable that each 

 species is restricted to a certain species of Salix. I have found in the 

 mouth of Boulder Caiion, Colo., bushes oi Salix htteosericea and Salix 

 bebbiana growing so closely together that the twigs were intermingled, 

 but in no case did I find C. macgillivrayi in galls on Salix bebbiana, 

 or C. bebbiana in galls on Salix luteosericea. 



It is at present impossible, unless the adults are reared, to deter- 

 mine with accuracy the galls of any species, with the exception of 



