INSECTS INJURIOUS TO SMALL GRAINS 143 



uniform grayish or 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 Professor F. M. Webster, who found that a larva collected 

 on June 15, 1897, entered the ground in about ten days, and 

 the first adult emerged January 11, 1898, though the adults 

 usually appear later. 



The most common saw-fly feeding upon wheat foliage is 



FIG. 104. A wheat saw-fly (Dolerus arvensis Say) : female much enlarged. 

 (After Riley and Marlatt, U. S. Dept. Agr.) 



Pachynematus extensicornis Norton. " The adult insects appear 

 during the latter part of April and first of May, the males antedat- 

 ing 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 elongate, 

 tapering gradually from the head to the last segment; head yel- 

 lowish, eyes black. Full growth is attained in about five weeks, 



* Family Tenthredinidte. Wheat and Grass Saw-flies. C. V. Riley and 

 C. L. Marlatt, " Insect Life," Vol. IV, p. 169. 



