. Bulletin of the Department of Agriculture. Agriculture; Agriculture. THE WESTERN GRASS-STEM SAWFLY. sorts provided the stem is sufficiently large for the larval gallery. As a rule, the larger, more robust stems are chosen for attack, espe- cially in cultivated grasses such as timothy and Bromus. Blue grass and similar slender-stemmed species appear to be immune. It is a little surprising that a minute examination of Stipa viridula from New Mexico developed the fact that none of the stems of this robust grass were infested. This Stipa was gathered in northern New Mexico, growing in almos
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. THE WESTERN GRASS-STEM SAWFLY. sorts provided the stem is sufficiently large for the larval gallery. As a rule, the larger, more robust stems are chosen for attack, espe- cially in cultivated grasses such as timothy and Bromus. Blue grass and similar slender-stemmed species appear to be immune. It is a little surprising that a minute examination of Stipa viridula from New Mexico developed the fact that none of the stems of this robust grass were infested. This Stipa was gathered in northern New Mexico, growing in almost the same latitude as the Elymus condensatus near Pinto, Utah, where the fly abounds. August 25, 1916, the writer, then at Pierre, S. Dak., received instructions from the Bureau of Entomology to visit Bottineau County. Fig. 4.—Wheat field of Thomas Yearn, near Souris, N. Dak., showing heavy damage done by the western grass-stem sawfly in 1916. in North Dakota and investigate injury to wheat. It was believed locally that the Hessian fly was responsible for the damage that was being done. A very superficial examination of the injured fields proved beyond a doubt that the Cephus was present in large numbers and was doing an immense amount* of mischief. Every field was infested, not only in Bottineau County, but in the adjoining counties of Benson, Pierce, McHenry, and Rolette. Near Souris, a few miles south of the Canada line, a large field of wheat on the farm of Thomas Yearn was fairly carpeted with the "straw-fallen" grain. (See figs. 4 and 5.) The loss from Cephus injury in this field was estimated at 60 per cent or more. Six feet of drill row here were taken at random and examined plant by plant. Forty-eight infested stubs were found,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United Sta
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