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 larvae 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 
this 
the life histor} T of Cephus was learned. Most of the facts in 
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 ine'rmis near Merricourt, 
N. Dak., in Elymus canadensis at Shakopee, Minn., in practically all 
these grasses near Sioux City, Iowa, and in wheat, timotlry, 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 
