The Enemies of Trees 



and snap off. Black locust, one of the most valuable post timbers, 

 is ruined wherever it grows now in the East by the locust borer. 



Sucking insects are a vast aggregation of species whose bond 

 of similarity is the beak or proboscis, by means of which they 

 puncture the skin of fruits, leaves, twigs or roots and suck the 

 juices there found. To this class belong the deadly scale insects, 

 the plant lice, bark lice, true bugs, weevils, etc. 



Chewing insects eat the substance of the leaf or other parts. 

 The caterpillars of many butterflies, moths and beetles are 

 chewers. Borers belong to this class. 



It is quite out of the question to attempt in this volume a 

 discussion of a subject so vast as the insect enemies of trees and 

 the methods science has devised to combat them. Horticulture 

 has led the way, of course. Publications covering all that is 

 known on the subject are issued by the Department of Agriculture. 

 Experiment stations in the different states are investigating this 

 subject and reporting progress in bulletins, which anyone within 

 the state may have for the asking. Besides, a growing body of 

 literature on the subject is being issued by various publishers of 

 scientific books. 



Spraying and fumigation are the two methods now in use 

 for the wholesale destruction of insects. They are developed to a 

 high degree by fruit growers. Power spraying has been intro- 

 duced by park commissioners in a few large cities for the protection 

 of shade trees. It promises to grow in popularity wherever 

 public spirit is strong and trees are threatened, as they are 

 with the gypsy-moth plague near Boston. Study of the life 

 history of different insects and fungi reveals their various weak 

 points and helpless stages. The principles and practice of spray- 

 ing depend for success upon this intimate knowledge. 



Boring insects cannot be reached by spraying. They are dug 

 out of fruit trees or destroyed by running a wire up the burrows, 

 It is the grub that does the damage. 



Chewing insects that live on trees are killed by spraying poison 

 on their food. Paris green, dissolved in water, and arsenate of 

 lead are commonly used. The younger insects are sprayed the 

 better. 



Sucking insects are killed by spraying with kerosene and water, 

 or with an emulsion of whale-oil soap, and with lime and sulphur 

 washes. The oil chokes the breathing tubes which are along the 



5.6 



