Chapter I. 

 INSECTS INJURIOUS TO THE OAK. 



Various species of Quercus. 



The oak perhaps affords our most valuable lumber, whether ship- 

 timber, carriage wood, or when used for carved work, floors, or furniture. 

 As a shade tree it will always be in demand, while groves of oaks are 

 among the chief ornaments of parks. The oak can be easily planted, 

 and it is one of the trees most available in the renewal of our forests. 



Unfortunately the oak is preyed npon by a larger number of kinds of in- 

 sects than perhaps all the other hard-wood forest trees mentioned in this 

 work put together. From the roots to the extremity of the smallest twigs, 

 including the buds and acorns, there are assemblages of insects which 

 divide the arboreal territory among themselves, not often encroaching 

 on each other's domain. In this way the work of destruction often be- 

 comes thoroughly well done. Yet, considering the number of species of 

 insects which prey upon this devoted tree, particularly when isolated from 

 its fellows, it is a wonder how evenly preserved is the balance of nature. 

 Undoubtedly, as in all other trees and most vegetable growths, a cer- 

 tain amount of natural, healthy pruning is accomplished by insects. 

 But were there not a complicated system of checks, particularly those 

 due to parasitic insects and to unfavorable climatic changes, the tide of 

 insect life would sweep away every tree and shrub from the face of the 

 earth. 



In his work on " Plant-Enemies of the Class of Insects," Kaltenbach 

 enumerates five hundred and thirty-seven species of insects of all orders 

 which in Germany prey upon the oaks of that empire. 



It is probable that nearly if not quite as many will be found in a re- 

 gion of the same extent in this country, especially since the species of 

 oaks are more numerous in the eastern United States than in central 

 Europe, the number of species in the latter region being but two or 

 three to twenty in the United States, east of the Eocky Mountains. 



The number of determined species of oak insects recorded in the fol- 

 lowing pages is over 400, while the number of undetermined species 

 would carry the number up to over 500, or about as many as Kaltenbach 



48 



