Pests and Diseases 187 



the most serious in one locality are not known in others. 

 Certain insects, though present in a locality, may do very 

 little damage even when serious elsewhere. Such insects 

 as the leaf-hopper are greatly affected by geography. 

 In some places they have rendered successful beet-culture 

 practically impossible, though in other sections the injury 

 is but slight. Treatments must, therefore, be applied 

 locally. No general description will suit all conditions. 



Blister-beetles (MeMdae). (Plate XXI.) 



These insects sometimes descend in swarms on field 

 and garden crops, destroying the foliage and ruining the 

 crops. No less than a dozen species of blister-beetles 

 work on crops. The insect is a long, narrow beetle with 

 a distinct head and "neck." In color it is black, gray, or 

 mottled, with a black or yellow stripe running the length 

 of the wings on most species. The grubs, or larvae, of 

 the blister-beetle feed on grasshopper eggs, and when the 

 grasshoppers are more injurious than the beetles, it may 

 pay not to disturb the beetles. The beetles may be kept 

 from the leaves by applying bordeaux mixture. When 

 this spray is made up with paris green as a constituent, 

 it may be beneficial. When the attack is sudden, the 

 usual method of control is to drive the insects from the 

 field by a number of men swinging branches over the 

 crop. The beetles move ahead of such a disturbance and 

 do not return quickly after once having been expelled. 



Army-worms. 



The beet army-worm (Caradrina [Laphygma] exigua 

 Hbn.) occurs in disastrous abundance on beets at certain 



