2 BULLETIN 841j U. S. DEPARTMENT OF AGRICULTURE. 
chance to feed upon the various cultivated plants grown in bulk by 
the farmer or gardener, many of these insects gradually desert their 
native host plants and to a greater or less degree change their habits, 
including in their fare the more succulent and easily found food. 
HISTORY 
The existence of the western grass-stem sawfly was first made 
known in 1S90 when Mr. Albert Koebele reared adults from larvae 
that were mining in the stems of native grasses growing in the vicinity 
of Alameda, Calif. 1 During the next year, 1891, the species was 
described under the name of Cephus oceidentaMs by Messrs. Kiley and 
Marlatt, from a series of individuals reared bv Mr. Koebele and also 
Fig. 1. — Western grass-stem savrfly ( Cephus cinctus] : Adult female. Much enlarged. 
from cotypes that had in the meantime been collected in Xeyada 
and Montana. 2 In connection with this description the prophetic 
suggestion was made that: "The economic importance of this species 
arises from the fact that it may be expected at any time to abandon 
its natural food-plant in favor of the small grains, on which it can 
doubtless successfully develop." 
Nothing more was heard of this sawfly until 1S95, when the late 
Dr. James Fletcher, Entomologist to the Dominion of Canada, swept 
adults at Indian Head, Northwest Territories, on July 5. He believed 
it to belong to the European species, Ce pirns pygmaeus L., and under 
» Koebele, A. Notes. In U. S. Dept. Agr. Div. Ent. Insect Life, v. 3, p. 71, 1890. 
2 Riley, C V., and Marlatt, C L. Wheat and Grass Saw-Flies. In U, S. Dept. Agr. Div. Ent. Insect 
Life, V. 4, p. 16S-179, 1891, (See p. 177-178.) 
