320 



YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



before it is burned. All infested tops and branches of summer cuttings 

 should be destroyed, and the bark removed from infested logs dur- 

 ing the winter. Therefore, clean forest management and the prompt 

 felling and removal of the bark from dying trees will serve to prevent 

 serious harm from this insect. 



BARK-BEETLE INJURIES TO OTHER TREES. 



The wild cherry is sometimes killed or seriously injured by the 

 cherry bark-beetle (Phlceophthwus limitiaris Harris), but this insect 

 rarely attacks perfectly healthy trees, although it is capable of doing 

 so. The ornamental double transverse gallery of this beetle in the 

 inner bark and grooves of the surface of the wood will be easily 

 recognized by the characteristic form, as shown in fig. 31, although 

 they are seldom found so perfect. 



The paper birch and other birches of the north woods and higher 



Allegheny Moun- 

 tains are sometimes 

 killed by the birch 

 bark-beetle (Dryo- 

 c&tes eickhoffi 

 Hopk.). Trees 

 slightly injured b}^ 

 fire, which would 

 otherwise recover, 

 often die from the 

 attack of this insect, 

 yet in such trees 

 they breed in such 



FIG. 32. Work of the birch bark-beetle: primary galleries and larval num bers as to attack 

 mines in bark. (Original.) 



living ones and kill 



them. The galleries made by this beetle and its larvse in the inner 

 bark (fig. 3:2) differ from the preceding in having no regular form, but 

 penetrate in all directions from the main entrance and the irregular 

 primary galleries. 



The hackberry bark-beetle (ftcolytus muticus Say), the elm bark- 

 beetle (Ilylastinm rufipes Eichh.), the mulberry bark-beetle (Phlwopk- 

 thorusfrontaUs Oliv.), the ash bark-beetle (Meliobius aculeatus Say 

 fig. 33), and a number of others of this class of beetles, are sometimes 

 quite injurious, but more often are secondary enemies which attack 

 only injured trees and prevent their recovery. 



OAKS, CHESTNUT, BIRCHES, AND POPLARS KILLED BY BARK-BORING GRUBS. 



There has been a great mortality among the oaks and chestnut of 

 the Appalachian region which has been going on for many years. No 

 such large bodies of timber have been killed in any one year as to 

 attract special attention, but scattering trees all through the forest die 

 every year. In some of the southern sections nearly all of the larger 



