i86 FORESTS AND MANKIND 



forest and city shade trees. Today the Japanese beetle, a newly 

 imported defoliator looms as a gigantic menace to our Eastern 

 city and forest trees. 



The spruce bud worm which lays its eggs in the needles of 

 balsam spruce has destroyed timber throughout hundreds of 

 square miles in Eastern Canada. The tent caterpillar is a 

 familiar pest in the Eastern states. 



For this class of insects control measures vary. In the case 

 of lawn and street trees, spraying the leaves with poison is 

 successful in killing many of the caterpillars, but for forest 

 trees such intensive measures are usually out of the question. 

 Plantations have been successfully sprayed by airplane but in 

 the forest little real progress has been made in the technique 

 of control against this class of insect attack. The cost is prohibi- 

 tive. Probably the best progress will be made in seeking out the 

 insect enemies of these pests and setting them loose to breed 

 and prey upon the defoliators. 



Fungi, too, take toll of the forest. The chestnut blight that 

 a few years ago practically exterminated our chestnut and 

 killed over fifty million dollars worth of timber is a fungus 

 disease. It attacks only chestnut, but of this doomed species it 

 has spared practically none. This fungus spread by wind and 

 birds works in through the bark of the tree, works rapidly 

 about the trunk, and at last cuts off the flow of sap. 



The various rots in trees heart rot, white rot, white pine 

 blister rust, all the many diseases that form toadstools on the 

 trunks and branches are fungus diseases. Actually we know no 

 practical way of combating them. About the only method of 

 defending the forest against their attacks is to cut the infected 

 trees and remove them before they spread disease to their 



