28 
is only a short distance above the ground. These develop and produce 
the adult of the second generation in June. This generation is much 
larger and more robust than the spring generation, and consists entirely 
of females provided with fully developed wings. They are therefore 
capable of flying readily about and constitute the migratory brood. 

Fig. 15.—Wheat straw-worm (Jsosoma grande), fall generation much enlarged (from Howard). 
The eggs from this brood of large-sized females are deposited in or 
near the joints of the straw, more frequently near the second joint 
below the head. The worms on reaching maturity enter the pupal or 
chrysalis stage in the fall and emerge as adults the following spring. 
Parasitic enemies.—Both of these insects are subject to the attacks of 
a number of parasitic flies which, as a rule, keep them pretty well in 
61 ES 

Fic. 16.—Wheat straw-worm (Isosoma grande), spring generation: a, b, larva; /, female; g, fore-wing; 
h, hind-wing; all much enlarged (from Riley). 
check. The damage from the wheat straw-worms is not often of a 
serious nature, but is quite general, and is probably very commonly 
overlooked on account of the concealed habits of the laryee, and this 
is especially true of the wheat straw-worm, the falling of the grain 
being often attributed to other causes. 
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