6 io PARMERS’ BULLETIN 637, 
tion is present that these natural enemies become sufficiently abundant 
to offer the farmer prompt and effective relief. In other words, the 
natural enemies, however much restraining force they may present, 
are always too far behind wholly to prevent occasional outbreaks of 
these grasshoppers. The farmer, haying undertaken the cultivation 
of alfalfa in large areas under conditions preeminently favorable for 
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Fic. 6.—A view of grasshoppers dead and dying from fungous disease. Natural 
size. (From Howard.) 
the development of grasshoppers, must now throw some restraining 
element into the other side of the scales in order to preserve the 
balance. It thus comes about that artificial repressive measures 
must be put into play in order to counteract, as it were, the effect on 
nature of an overabundance of alfalfa plants—a vastly greater num- 
ber than would be produced under natural conditions. And this 
brings us. to a consideration of preventive and repressive measures. 
