28 BULLETIN 544, U. S. DEPARTMENT OF AGBICULTUKE. 



sylvania; but thus far the eastern spruce beetle is credited with 

 confining its baleful activity to the spruce alone and to areas north 

 of West Virginia. Both of these insects attack perfectly sound, 

 thrifty timber of the best quality — that is, trees from 10 to 12 inches 

 hi diameter and larger. Although they manifest a preference for 

 standing trees, thej will breed in windfallen trees and, more rarely, 

 m stumps and logs. 



Certain insects which infest the spruce are able to do their work only 

 when the vitality of the tree has been reduced either by a former 

 insect attack or through disease. The wood miners work within the 

 wood}" parts of the tree rather than in the cambium, and continue 

 their work after its death, as well as in the log after it is cut. They 

 are usually of no detriment to the health of the living tree, but their 

 excavations into both the heartwood and sapwood cause wormhole 

 defects and afford favorable means for the entrance of fungi. 



While the insect enemies of spruce have many natural enemies, 

 such as the birds, parasitic insects, and fungi, and predacious insects 

 which feed on and destroy their young, their ravages are not always 

 held in check by such means. According to Dr. A. D. Hopkins, 1 

 forest entomologist of the U. S. Bureau of Entomology, the general 

 methods to be adopted are as follows: 



For the southern pine beetle: (1) remove and burn the infested 

 bark from the trunks of the trees while still standing; (2) place the 

 infested portions of the trunks in water; or convert the infested trees 

 into cordwood, lumber, or other products and burn the slabs or bark 

 before the beetles leave the bark. 



For the eastern spruce beetle: (1) Regulate the winter cutting so 

 as to include as many of the infested, dying, and dead trees as pos- 

 sible, and place the logs from tnem in water before the first of June; 

 (2) regulate the summer cutting so that as many recently attacked trees 

 as possible may be cut and the bark removed from the trunks and 

 stumps; (3) girdle, early in June, a large number of trees, in the 

 a icinity of infested localities where logging operations are to be 

 carried on the following summer and winter, the girdled trees to be 

 felled and the logs containing the broods of the insect attracted to 

 them either peeled or placed in water before the first oi the succeeding 

 June. The trees selected to be girdled should be sound and healthy 

 and not loss than 15 inches in diameter, and the girdling should be 

 done by hacking the tree with an ax through the bark into the sap- 

 wood and around the trunk 2 or 3 feet above the has.-. 



A large percentage of dead spruce remains sound for a considerable 

 period after being killed by these insects, and should be salvaged when 



i U. 8. Department of Agriculture, Div. Ent. Bulletin 28; also U. S. Department of Agriculture Farmers' 

 Bulletin 476. 



