54 ANIMAL BIOLOGY 



buried in the ground. The little, yellow, black-spotted 

 cucumber beetle and the elm-leaf beetle which has caused 

 so much damage to the elm trees in the eastern states 

 are other destructive pests belonging to the same family as 

 the potat o bug. 



The boring beetles, of which there are large numbers, 

 include many destructive enemies of trees and shrubs. 

 The larvae, and in many cases the adults also, live upon 

 the wood, forming tunnels which sometimes result in 

 completely girdling the tree. The pupae usually lie in 

 the burrows and the mature insect gnaws its way to the 

 outside. 



FIG. 46. Female of FIG. 47. A click beetle. 



the Vedalia beetle. 



Among the beetles which are beneficial to man are to 

 be counted the lady beetles which are of small size and usu- 

 ally hemispherical in outline. In both larval and adult 

 stages they prey upon plant lice, scale bugs and other 

 insects. The Novius previously mentioned which prac- 

 tically exterminated the cottony-cushion scale is a species 

 of the lady beetle family. 



Less useful, but on the whole beneficial beetles are the 

 scavenger or carrion beetles which feed upon the decay- 

 ing bodies of animals, which they can detect at a consider- 

 able distance through their remarkably acute sense of 

 smell. There are numerous water beetles belonging to 

 several distinct families. The Gyrinidae, or whirling 

 beetles, which are the analogues of the pond-skaters 



