142 ELEMENTARY STUDIES IN INSECT LIFE 



the brood is few in ninnlior the larva finds, without 

 much moving- about, sufficient nourishment to satisfy it. 

 When the brood is large, as is sometimes the case, the 

 caterpillars are forced to travel in order to satisfy their 

 natural cravings for food. 



These insects are two-brooded. The second or mid- 

 summer brood is the one which furnishes the largest 

 army of worms. Some of this midsummer brood 

 emerge before winter to lay eggs, and others pass the 

 winter in the pupal stage. It is probable that the ma- 

 jority of these insects spend the winter in the larval or 

 pupal state. If the ground is stirred by plowing or 

 harrowing in the early spring, it is evident that the 

 majority of the hibernating larva? and 

 pupa' will be destroyed. Mechanical 

 means, such as the cutting down of the 

 crop on the edge of the field where the 

 caterpillars are entering, and destroying 

 this crop by fire, are effective, since the 

 larva 1 are burned with the crop. The 



FIG. 113. Thepo- . 



tato beetle (Dory- march oi this enemy can sometimes be 



phora 10-lineata). ( .}^}^] j )y p l mv i n g a furi'OW aCl'OSS its 



front and dragging a log back and forth through the 

 furrow, crushing the insects as they crawl into the 

 furrow. 



The Potato Beetle. An insect which has been of great 

 importance in connection with potato culture is the 

 well-known potato beetle, 1 ten-line beetle, or Colorado 

 beetle. This insect passes the winter in the adult or 

 pupal stage, and comes forth in the early spring to 



^Doryphora 10-lineata 



