64 THE HUMAN SIDE OF TREES 



dicates that their shorter-lived fellows have suc- 

 cumbed to adverse conditions of some kind. Among 

 the things with which they contend are uncon- 

 genial environment, mechanical injuries, insect and 

 fungous enemies, and physiological troubles. 



It takes an expert in tree pathology to correct 

 some of these ailments, but others can be detected 

 and done away with by the untrained eye and hand. 

 Even a city-bred man knows that caterpillars are 

 not exactly a benefit to the foliage of a tree. When 

 they, or any other insect pest, become too numer- 

 ous, the tree should be sprayed with a death-dealing 

 chemical. In California they often fumigate whole 

 fruit orchards with some such gas as hydrocyanic 

 (prussic) acid. Companies organised for the pur- 

 pose will undertake to rid a whole group of trees 

 of their insect enemies for twenty or thirty cents 

 a tree. The work is often done at night, and a 

 common method is to drop a canvas tent over each 

 tree, within which the deadly fumes are generated. 



If a man has a blood-poisoned arm the doctors 

 cut it off. In the same way dead and decaying 

 limbs should be removed from trees. If a man 

 has a weak or injured leg he is given a crutch on 

 which to lean. It is only fair to help the trees by 

 providing bolts and supports for their weak mem- 

 bers. Moreover, these surgical helps should be 



