THE MONTHLY BULLETIN. 



71 



The following generalizations in regard to the injury done bj^ the 

 larvte of the second generation may be made : 



Infestation of very young plants may kill them or cause them to stool 

 excessively. 



Infested stems are usually, but not always, shorter and have smaller 

 heads than stems that are not infested. 



Early infestation, particularly in the lower joints, affects the height 

 and size of the stem and the size of the head, usually making the head 

 small or verv small. 



Fig. 30. — Wheat straws that have 

 been badly injured by the larvae of 

 Isosoma grande. (Original.) 



An early infestation of the highest or next to highest joint affects the 

 size of the head but does not appreciably affect the height of the stem. 



Infestation of the third joint does not seem to affect the plant as 

 seriously as infestations higher or lower, made at approximately the 

 same time. 



A very late infestation may occur in one, or even in two or three 

 joints, without seriously affecting the stem or the head. 



CONTROL. 



As the insect passes so much of its life in the straw or stubble that is 

 usually left on the field, and as the adults of the first generation are 

 wingless, simple eft'ective remedies are at once suggested. If all of the 

 straw and stubble can be burned, the over-wintering larvaj and pupa^ 

 will be quickly destroyed, or if the fields are carefully plowed so that 

 all of the stubble is deeply buried, few of the insects will survive. It 



