22 



In their life history blister beetles differ greatly from other Cole- 

 optera in that they undergo a more complicated series of metamor- 

 phoses which will be explained and illustrated in the account of the 

 striped blister beetle which follows. 



Blister beetles are not an unmixed evil, since they do some good in 

 their larval stage to compensate in a measure for the harm the beetles 

 occasion to our crops, for the habit of the larvae of destroying grass- 

 hopper 3ggs renders them of material aid in keeping these pernicious 

 insects in check.. This is especially true in the Western States, where 

 both blister beetles and grasshoppers abound. But the benefits derived 

 are really more than counterbalanced by the losses occasioned in fields 

 and gardens; hence, insecticides and other measures should be 

 employed to destroy the l)eetles when they occur in harmful numbers. 



As blister beetles are to be found in practically all fields of sugar 

 beet, and are among the most prominent enemies of this plant, it is 

 purposed to consider several of the most abundant species. 



THE STRIPED BLISTER BEETLE. 



( Epicauia vittuta Falj. ) 



Before the advent of the Colorado potato beetle in the East this was 

 our most destructive potato insect, and probably because it is also 



b e 



Fig. 13.— Epicauta rittata: a, female beetle; b, eggs; c, triungulin larva; d, second or caraboid stage; 

 e, same as /, doubled up as In pod; /, scarabieoid stage; g, coarctate larva — all except e enlarged 

 (after Riley, except a; original, Division of Entomology). 



striped is often called the " old-fashioned potato bug." It is abundant 

 and well known east of the Rocky Mountains, of common occurrence 

 on sugar and table beets, and as its life histor}^ is typical of injurious 

 forms of this group it may properly receive first attention. The beetle 

 can be easily identified by means of the illustration (fig. 13, a). It is 

 about half an inch long, and there are two black stripes on each wing- 

 cover, alternating with yellow. 



The eggs are laid in small masses (h) on plants or upon the ground. 

 From each hatches a small long-legged larva, called a "triungulin" (c), 

 which runs actively about in search of a grasshopper egg pod, which 



