CHAPTER VIII 



INJURIOUS INSECTS, FUNGOUS AND OTHER 



DISEASES 



Besides being subject to injuries resulting from condi- 

 tions of artificial city environment and abuse, as just de- 

 scribed, trees have natural parasitic enemies such as insects 

 and fungi, and also suffer from diseases in which the con- 

 ditions of soil and climate are the controlling factors. 



TREATMENT OF TREES FOR INSECT PESTS 



The most vital task, by far, in the care of trees is the 

 extermination of the insects that threaten to destroy or in- 

 jure them from time to time. The great damage inflicted 

 by insects on shade-trees throughout the country is usually 

 underestimated. A fully grown shade-tree is a valuable 

 asset to any property, and while it is not always possible to 

 estimate its loss in financial terms it must be remembered 

 that it may have taken a lifetime to grow. The value of 

 street-trees is infinitely greater than their cost of planting. 

 They are treasures which should be most jealously guarded. 

 To give an idea of the extensive damage caused by insects 

 attention need be called only to the depradations of the elm- 

 leaf beetle. From 1898 to 1905 it caused the death of sev- 

 eral thousand trees in Albany and Troy alone, besides seri- 

 ously weakening many others. The leopard moth is a very 

 serious borer, which has become established about New York 



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