4 BULLETIN 841, U. S. DEPARTMENT OF AGRICULTURE. 



August 20, 1909, Prof. H. B. Penhallow reported from Sherwood, 

 N. Dak., that he had examined about a hundred fields from Minot, N. 

 Dak., north to the boundary line and several miles into Canada and had 

 found larvse present in every field but one. He estimated the damage 

 in these fields as ranging from 5 to 25 per cent of the crop, but spoke 

 of one field about 27 miles east of Sherwood where the damage was 

 said to have exceeded 66 per cent. R. W. Sharpe reported similar 

 damage in the Red River Valley, near Fargo, N. Dak. 



During 1911 and 1912 the writer found the species occurring freely 

 in the native grasses in various parts of Utah, and as occasion offered 



Fig. 3. — Plants of Elymus condensatus growing along the railroad right of way. 

 the western grass-stem sawfly in Utah. 



The natural habitat of 



the life history of Cephus was learned. Most of the facts in this 

 paper are the result of this study. (Fig. 3.) 



During the years 1913, 1914, and 1915 the writer has found this 

 sawfly almost universally distributed over the Dakotas, Minnesota, 

 Iowa, and Nebraska, feeding in Elymus, timothy, and Agropyron at 

 Elk Point, S. Dak., in Agropyron tenerum near Chamberlain, S. Dak., 

 in timothy at Edgeley, N. Dak., in Bromus indrmis near Merricourt, 

 N. Dak., in Elymus canadensis at Shakopee, Minn., in practically all 

 these grasses near Sioux City, Iowa, and in wheat, timothy, and 

 Elymus near Minot, N. Dak. It seems to have little choice in the 

 various native grasses and is ready to attack any of the cultivated 



