9 



tioii with tho exhil)it of tho Rnrcaii of ForestiT. Tho cxliildt shows 

 thi' thuructvr of work of some of the most dostructivc cncinirs of for- 

 ests and tho iiisct'ts which are responsible for the (lama j(e. The hibels 

 vr'wo ireneral information rej^ardin*;' the insects and their habits, which 

 will aid the forester and the hinit»t'rmaii in recognizing- them when met 

 with. 



Section IV. —PHOTOGRAPHS OF INSECT DAMAGE TO FORESTS. 



The photographs of insect damage are enlarged from 4 by r» and H 

 by 7 negatives taken l)y tiie author and his assistants, and show some 

 of the features of insect work which could not well l)e represented by 

 specimens. 



GENERAL DESCRIPTION OF THE EXHIBIT. 



A larg(> amount of the material in the exhibit represents the first of 

 the kind collected, and many of the descriptions of the work, host 

 plants, habits of tli(^ insects, etc., on the labels and in this catJiiogue. 

 are original. 



The exhibit represents several (juite distinct classes of enemies, as 

 related to orders and groups of insects, the parts of trees att^icked, 

 primary or secondary injuries, etc. This is indicated to a certain 

 extent l)y the arrangement of the specimens in the cases, and bj- the 

 labels; but in order to prevent duplication in the catalogue, the 

 descriptions of the principal classes of insects and the character of 

 their work are included in the introduction, classified primarily accord- 

 ing to the part of the tree or kind of product injured, and secondarily 

 according to the class of insects which have similar habits. 



The term "trunk and branches" not onl}' refers to living tices. l)ut 

 to dying, dea<l. and felled trees, sawlogs, and like crude products. 



INSECTS INFESTING THE BARK. 



HA HK -BEETLES. 



[PLATK8 I-VIU.] 



This class of beetles attacks living, dead, and recently felled trees. 

 Th(> parent adults excavate their brood galleries through the inner 

 layers of bark and often groove the outer surface of the wood. Their 

 eggs are deposited along the sides of the galleries and the young 

 >)i-oods develop in the i)ark and transform to the adult eithei- in the 

 bark ()r outer sapwood. Some of the sjiecies attack living trees, 

 causing their rapid death, and are among the most destructive enemies 

 of AmiMican forests; others are of .secondary importance in attacking 

 the injured trees and contributing to their death, while still others 

 attack onlv the l»ark and twigs of dviii'j- and d«'ad trees. 



it 



