62 CONTROL BY MECHANICAL MEANS 



such as the shot-hole borer. The hmbs or trees removed should be 

 converted at once into cord wood and burned. Otherwise, little will 

 be gained by their removal. 



Use of Traps 



The kinds of traps are legion, and range all the way from chips or 

 stones placed in the garden for squash bugs to hide under to more or 

 less ingenious devices for capturing roaches and flies. Many are 

 efficient, though it often seems that new individuals make their appear- 

 ance about as fast as the others are caught. At best the total numbers 

 merely are reduced. 



A variation of traps is seen in the use of trap crops. By this device 

 some kind of plant is introduced that the pest is fond of, and after the 

 insects have collected on these plants, they are destroyed by poisoning, 

 burning, or by spraying them wdth some oil or corrosive, such as pure 

 kerosene. In other cases the trap precedes the regular crop, and 

 thus diverts attack from the more valuable plant. Thus, early kale is 

 sown in fields that later are to be set out to cabbages, in order to attract 

 the overwintering adults of the harlequin cabbage bug. 



