THE BEETLE AND ITS ALLIES 55 



States is the ten-lined Colorado potato-beetle, Doryphora 1 

 decemlineata. Until about 1859 this species fed upon the 

 sand-bur {Solanum .ro stratum), at the eastern base of the 

 Rocky Mountains and south into Mexico. 

 With the advent of settlers and the plant- 

 ing of the cultivated potato {Solanum 

 tuberosum, a native of Mexico), this more 

 thrifty, cultivated species was adopted as 

 its food-plant, and the potato-beetle began 

 its eastern migration. It spread slowly at 

 first, but within fifteen years had reached 

 the Atlantic coast. The little red, yellow, 

 and black asparagus-beetle^ the yellow, 

 black-striped cucumber and melon beetle, 

 the tortoise-beetle, whose broad, iridescent, 

 translucent elytra are conspicuous on the 

 leaves of the morning-glory, nettle, and 

 other plants, all belong to this family. 



So long has become our list of destructive 

 beetles that it is with satisfaction that we 

 turn at the end to a family which is almost 

 wholly beneficial to the vegetable kingdom, 

 as well as to most vegetable-feeders, includ- 

 ing man. This is the ladybird family, FIG. 59. Cyliene 

 Coccinellidae. These beetles are preda- Un ^ , the ^ cust 



x borer, found on 



ceous, both in the larval and adult stages, the golden - rod. 

 feeding upon small insects and insect eggs ^ h p t0 ' by w> H '' 

 (Figs. 60 and 61). They are especially 

 active in freeing plants from scale-insects and plant-lice. 

 So rapidly do the latter multiply that were it not for the 

 voracious larvse of the ladybird most plants would be 

 1 5o/>u06/>os, spear-bearing. 



