114 PROTECTION OF PLANTS, 1915-16 



Host Key to Insects Injurious to Cereal Crops 



Roots. 



(a) Plants stunted, yellow, and withered or dead; roots eaten. 



(1) Smooth, slender, wire-like, 6-legged worms present in the 

 soil. Wireworms. 



(2) Present in the soil large soft-bodied whitish grubs, with brown 

 heads, and hinder portion of body thicker than fore end. When 

 disturbed grubs curl up. White Grubs. 



(3) Large dirty brown maggots, 3^-1 inch long. Meadow Maggots. 



Stems and Leaves. 



(a) Young plants dwarfed, and color changed to yellow or brown; 

 stems shrivelled at the base, often bent or broken off, flaxseed 

 objects found embedded at or near the base. Oats immune. 

 Hessian Fly (Mayetiola destructor.) 



(b) Stems above last joint dead, and the heads white, — "silver top" or 

 "white head" disease. Greenish maggot in stem above last joint. 

 Wheat Stem Maggot (Meromyza Americana) and American Frit-fly 

 (Oscinis carbonaria) . 



(c) Swellings or galls on the joints, and the stems bent or broken before 

 harvest. Joint Worm (Isosoma tritici). 



(d) Stems broken down and tunnelled, blackish near the joints; heads 

 turning white; presence in tunnel of yellowish-white grub of saw- 

 fly; oats immune. Western Wheat-stem Saw-fly (Cephus occiden- 

 talis). 



(e) Leaves sickly and whitish; the presence of small red and larger 

 black and white bugs. Chinch Bug (Blissus leucopterus). 



(f) Stems and leaves sickly; the presence of many green plant lice. 

 Wheat Plant Louse (Aphis avenae) . 



(g) Stems and leaves eaten by large dingy striped caterpillars. Army- 

 worm (Leucania unipuncta). 



(h) Leaves eaten by locusts or grasshoppers. Red-legged and other 

 Grasshoppers. (Melanoplus femur-rubrum et al). 



