8 BULLETIN 808, U. S. DEPARTMENT OF AGRICULTURE. 



they are placed in the walls. Several eggs are placed occasionally 

 in the same joint but the writer never has found more than one 

 full-grown larva at a joint, the others apparently being killed by 

 the surviving larva. The larva rasps the inner walls of the stem, 

 sucks the juices, and subsequently forms a neat little cell within 

 the joint (PI. IV, B). In all the winter wheat areas the effect upon 

 the plant is to cut down the yield of grain, while in places where 

 both spring and winter wheat are sown, often in adjoining fields, 

 the summer form turns its attention to the spring wheat in prefer- 

 ence to the older and tougher plants of the winter wheat. Spring 

 wheat is affected very much in the same manner as winter wheat is 



Fig. 6. — Wheat straw-worm : Adult female of summer form {Harmolita grandis, 

 form grandis.) Greatly enlarged. (Webster and Reeves.) 



injured by the first generation (form minuta). The summer genera- 

 tion remains in the. old wheat stubble, pupating in the fall. The 

 spring generation, as previously stated, emerges in March and April. 

 The writer has never seen males of the summer generation, 



THE WHEAT SHEATH-GALL JGINTWORM.* 



Harmolita vaginicola was not described until 1916 (2), though 

 the typical form of its injury to wheat was recorded in literature 

 many years ago. There are specimens in the National Museum 

 collection that bear the manuscript name Pteromalus hordei Harris, 

 which were collected in Virginia in the early fifties, and some that 



''■H. vaginicola Doane. 



