184 FORESTS AND MANKIND 



In New England where white pine plantations are common, 

 but where in nature these pines usually occur in small groups 

 scattered among the hardwoods, foresters are fighting a hard 

 fight against the white pine weevil which lives on the main 

 twigs of the pine and seriously damages these plantations. Here 

 a rather remarkable observation has been made. On areas of 

 pure white pine beetles swarm to the attack in large numbers, 

 but when among the pine a few taller hardwoods are scattered, 

 the beetles fly over without attacking. It is as if the presence 

 of the taller hardwoods serve as a kind of protecting camou- 

 flage against the beetle air raid. 



Control methods against the hosts of forest enemies vary 

 with the particular type of insect. In the case of beetles, the 

 usual method of control is to cut down infected trees, peel 

 them, and burn the bark while the broods of beetles are still 

 inside. The Government has done a great deal of this work 

 in its fight against the destructive western yellow pine beetle. 



But bark beetles are not the only important insect enemy. 

 There is another great class of insect marauders known as the 

 leaf eaters. They include certain butterflies and moths, as well 

 as insects belonging to the same families as the wasp and bee. 

 To these leaf eaters or defoliators belong pests that have caused 

 many millions of dollars worth of damage and for whose con- 

 trol much money and human effort have been spent. 



The gypsy moth, the browntail moth, the spruce bud 

 worm already more than ten million dollars has been spent in 

 the fight against them. These defoliating insects usually lay 

 their eggs in the trees and the caterpillars hatching out feed 

 on the leaves and often strip a 'tree of its foliage completely 

 stopping growth and in extreme cases killing thousands of 



