n 



series. A seedling injured by one insect is more 

 likely to be attacked again, and by some other 

 insect, than is the sound seedling by its side. 

 Let a seedling be injured, and relays of insects 

 often several species at a time and each spe- 

 cies with a way of its own will attack it 

 through the seedling, sapling, pole, tree, and 

 veteran stages of its growth until it succumbs. 

 Or let a vigorous tree meet with an accident, 

 and like an injured deer it becomes food for an 

 enemy. If lightning, wind, or sleet split the 

 bark or break a limb, through these wounds 

 some spore or borer will speedily reach the tree's 

 vitals. In many cases the deadly work of para- 

 sitic plants and fungi is interrelated with, and 

 almost inseparable from, the destructive opera- 

 tions of predacious insects. Many so-called tree 

 diseases are but the spread of rot and fungi 

 through the wood by means of an entrance 

 bored by a borer, weevil, or beetle. 



The bark of a tree, like the skin on one's body, 

 is an impervious, elastic armor that protects 

 blood and tissues from the poisonous or cor- 

 rupting touch or seizure of thousands of deadly 



183 



