CHAPTER XIX. 



TREE INSECTS AND THEIR CONTROL 



TREES have several insect enemies. In a single season, 

 if allowed to work unchecked, an able-bodied colony 

 of these pests can undo the efforts of years on the part of 

 man and nature. Fortunately for the welfare of the shade 

 tree, most of the damage may be prevented or cured, and 

 it is to the ways and means of achieving one or the other 

 of these results that the tree lover will find he must give 

 careful attention. 



Because trees in the forest generally thrive in spite of 

 their insect enemies, it must not be figured that the 

 shade tree may be trusted to care for itself. The two situ- 

 ations are so different as to have little in common. In the 

 forest the tree has nature's equipment for defense, such 

 as ideal conditions for growth and for the development of 

 power of resistance to attacks, and birds and insects of 

 many kinds to destroy the pests and thus help keep them 

 under control. In the artificial environment of the town 

 or city the tree is at a disadvantage. In many situations 

 its life is a struggle for existence. It must overcome the 

 handicaps of packed soil, uncertain water supply, crowded 

 conditions, poisonous gases and the injuries of traffic and 

 lack of bird and insect protectors. Thus hampered, it is 

 not strange that the tree lacks the rugged vitality of its 

 forest kinsmen, and it is not surprising that it should be 

 less sturdy in its resistance to the attacks of insects. 



Damage by these natural enemies affects the tree in 

 different ways, ranging from injuries so slight as to call 

 for no attention, to the severe forms which prove fatal. 

 To combat the ravages of the insects requires watchful- 



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