WHEAT INSECTS 117 



October, and deposit eggs on young fall wheat 

 plants, where they hatch into larvae and pass the 

 winter; the larvae do the injury to young plants in 

 fall and spring. 



Control — Sow late as for Hessian fly. 



The greater wheat straw-worm ^ {Isosoma 



grande) 



Order — Hymenoptera 



This pest is mainly injurious west of the Missis- 

 sippi, but is distributed east. 



The adults always small and frequently wingless, 

 emerge in April from stubble and deposit eggs in 

 stems of young plants in or just below the embry- 

 onic wheat head; the larva eats out the embryonic 

 head of the wheat plants and usually causes a slight 

 enlargement of the stem ; adults appear from these, 

 large and robust in June, and deposit eggs in stems 

 just above the upper joints usually; by October the 

 larvae pupate and pass the winter in stubble. 



Control — Burn stubble; rotate crops. 



The wheat joint-worm ^ {Isosoma tritici) 

 Order — Hymenoptera 



First serious outbreak in Virginia in 1848-1854, 

 and reappeared in Indiana, Michigan, Ohio, Penn- 

 sylvania, Virginia, and Maryland in 1904-1908. ^ 



Lives over winter either as a larva or a pupa in 

 wheat straws; adults appear in April or May and 

 lay eggs in stems of plants at the joints ; larvae form 

 cells in stems and feed there until straw hardens 

 and grain ripens ; the larvae deform the straws, galls 

 being formed above the joints; grains remain small 

 and shrivelled or none produced; many of the af- 

 fected straws break and fall over. 



6 Webster and Reeves— U. S. Bu. Ent., Circ. 106. 



7 Webster— U. S. Bii. Ent., Circ. 66. 

 Houser— Ohio Expt. Stat, Bull 226. 



