INSECTS INJURIOUS TO WHEAT. 119 



Wheat Saw-flies {Dolerus spp.). 



Several species of saw-fly larvae sometimes feed upon the 

 leaves and rarely the heads of wheat, but seldom do serious 

 injury. Dolerus arvensis Say and Dolerus collar is Say 

 have both been reared upon wheat from Ohio and New 

 Jersey, though both species occur throughout the United 

 States and southern Canada east of the Rockies. The 

 adult flies "are comparatively large, robust insects, of a 

 dull black or bluish color, varied with yellow or reddish.^' 

 *^The larvae are quite uniform in color and general char- 

 acteristics. They have twenty-two legs, are cylindrical; 

 and generally of a uniform grayish o^ slaty color, dorsally 

 and laterally, but nearly white ventrally." * 



The adults deposit their eggs in the spring, and larvae 

 are to be found early in June. The only record found of 

 the life-history is that of D. collaris by Prof. Webster, 

 who found that a larva collected on June 15, 1897, entered 

 the ground in about ten days, and the flrst adult emerged 

 January 11, 1898, though the adults usually appear later. 



The most common saw-fly feeding upon wheat-foliage is 

 Pacliynematus extensicornis Norton. "The adult insects 

 ap23ear during the latter part of April and first of May, 

 the males antedating the females several days. The eggs, 

 when first laid, are of a light green color. They are 

 inserted to the number of two to five, or more, together 

 along the edges of the wheat-blades and just beneath the 

 epidermis. Some fifteen or sixteen days elapse before 

 hatching. The newly hatched larva is rather slender and 



* Wheat and Grass Saw-flies. C. V. Riley and C. L, Marlatt, 

 "Insect Liie," Vol. IV, p. 169. 



