36 OHIO EXPERIMENT STATION: BULLETIN 198. 



EXPLANATION OF PLATE HI. 



a The Hessian fly. In flaxseed stage at base of stalk. 



Negative by Houser 



b Joint worm in wheat straw. 



Photo by Goodvjin, 



c Joint worm larvae, enlarged. 



Photo by Goodwin. 



d Straws injured by joint worm showing enlargement and 

 woody portions j ust above the joints. 



Photo b^ Gnodwft^ 



