CHAPTER IX 



POTATO INSECTS AND THEIR CONTROL 



The amount of damage to the potato crop by insects 

 is very large, much larger than is ordinarily supposed. 

 Spraying with poisonous substances has to be resorted to 

 in order to obtain a crop which has been uninjured by 

 insects. They do four kinds of damage and may be clas- 

 sified in this manner: (1) insects chewing the leaves; 

 (2) insects sucking the leaves and tips ; (3) stalk borers ; 

 and (4) insects affecting the tubers. Most of the damage 

 is done by the Colorado potato-beetle and the flea-beetle. 



The Colorado potato-beetle (Leptinotarsa decemlineata) 

 (Fig. 10). 



This is a leaf-eating insect, and its ravages are very 

 general. It seems to be always present where potatoes 

 are grown, and the damage it causes is very great. Indeed, 

 in most sections, it is impossible to obtain a crop at all 

 unless its ravages are held in check by the application of 

 some poisonous substance to the leaves. 



This insect is a native of a strip of country which lies 

 just east of the Rocky jMountain range and includes eastern 

 Colorado. In its native state the beetle lives upon the 

 wild weeds of the potato family, the chief of which is the 

 sandbur (S. rostratum). It is a general feeder, living on 



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