s 
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 (PL 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 verv much in the same manner as winter wheat is 
Fig. 6. — Wheat straw-worm : Adult female of summer form {Harmollta 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 JOINTWORM. 1 
Harmollta 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 Xational Museum 
collection that bear the manuscript name Pteromalus hvrdei Harris, 
which were collected in Virginia in the early fifties, and some that 
X H. vaginicola Doane. 
