576 



THE STUDY OF INSECTS. 



paragus bearing the eggs of this beetle, also a beetle and a 

 larva enlarged. The beetle measures about a quarter of an 

 inch in length. Where this pest occurs 

 care should be taken to destroy all wild 

 asparagus. This will force the beetles to 

 lay their eggs upon the shoots that are 

 cut for market. The larvae hatching 

 from such eggs will not have a chance 

 to mature. 



The Colorado Potato-beetle, Do- 

 ry phor a decemlineata (Do-ryph'o-ra dec- 

 em-lin-e-a'ta). — A good many insect 

 tramps have come to us from Europe 

 and from Australia, and appropriated 

 whatever pleased them of our grow- 

 ing crops or stored grain. But two of 

 our worst insect pests have swarmed 

 out on us in hordes from their strongholds in the 

 region of the Rocky Mountains. These are the Rocky 

 Mountain Locust and the Colorado Potato-beetle 

 (Fig. 702). The latter insect dwelt near the base 

 of the Rocky Mountains, feeding upon the sand- 

 burr {Solatium rostratwri), until about the year 

 1859. At this time it began to be a pest in the 

 potato-fields of the settlers in that region. Having acquired 

 the habit of feeding upon the cultivated potato, it began its 

 eastward march across the continent, spreading from potato 

 patch to potato patch. At first the migration took place at 

 about the rate of fifty miles a year, but later it was more 

 rapid ; and in 1874 the insect reached the Atlantic 

 coast. 



The Three - spotted Doryphora, Doryphora 

 clivicollis (D. div-i-col'lis). — This resembles the 

 Colorado potato-beetle in size and form. It is 

 of a deep-blue color, except the wing-covers, which are 

 orange, with three dark-blue spots on each (Fig. 703). 



Fig. 



Fig. 703. 



