CHAPTER VI 

 THE CARE OF TREES 



STUDY I. INSECTS INJURIOUS TO TREES AND HOW 

 TO COMBAT THEM 



IN a general way, trees are attacked by three classes of 

 insects, and the remedy to be employed in each case 

 depends upon the class to which the insect belongs. The 

 three classes of insects are: 



1. Those that chew and swallow some portion of the 

 leaf; as, for example, the elm leaf beetle, and the tussock, 

 gipsy, and brown-tail moths. 



2. Those that suck the plant juices from the leaf or 

 bark; such as the San Jose scale, oyster-shell, and scurfy 

 scales, the cottony maple scale, the maple phenacoccus on 

 the sugar maples, and the various aphides on beech, Nor- 

 way maple, etc. 



3. Those that bore inside of the wood or inner bark. 

 The principal members of this class are the leopard moth, 

 the hickory-bark borer, the sugar-maple borer, the elm 

 borer, and the bronze-birch borer. 



The chewing insects are destroyed by spraying the leaves 

 with arsenate of lead or Paris green. The insects feed upon 

 the poisoned foliage and thus are themselves poisoned. 



The sucking insects are killed by a contact poison: that 

 is, by spraying or washing the affected parts of the tree 

 with a solution which acts externally on the bodies of the 



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