72 



The Stems and Leaves. 



1. Young plants dwarfed, and color changed to yellow or brown; stems 

 shrivelled at the base, often bent or broken off ; " Flax-seed " objects found em- 

 nedded at or near the base. — Hessaati Fly (Cecidomyia destructor). 



2. Stems above last joint dead, and the heads white — " Silver-top " or white- 

 head " disease. Greenish maggot in stem above last joint. — Wheat Stem SVIaggot 



(Meromyza x^mericana) and American Frit-J'ly (Oscinis carbonaria). 



3. Swellings or galls on the joints, and the stems bent or broken before 

 harvest. — Joint Worm (Isosoma tritici). 



4. Leaves sickly and whitish; the presence of small red and larger black and 

 white bugs. — Chinch Bug. (Bhssus leucopterus). 



5. Stems and leaves sickly; the presence of many green plant lice. — Wheat 

 Plant Louse. (Nectarophora avenae.) 



6. Stems and leaves eaten by large dingy caterpillars. — Arony-worm. (Leu- 

 cania unipuncta.) 



7. Leaves eaten by grasshoppers. — Red-legged grasshoppers (Melanoplus 

 femur-rubrum. 



The Heads. 



L Heads turn white and grains are shrivelled or imperfectly filled. — Wheat 

 Stem SVlaggot (Meromyza Americana) and American Frit-F3y (Oscinis carbo- 

 naria.) 



Wheat midge (Diplosia tritici); a, female .fly; b, mala fly; c, larva, ventril 

 view — all enlarged. (Marlatt). 



