28 BULLETIN 544, U. S. DEPARTMENT OE AGRICULTURE. 
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 
in diameter and larger. Although they manifest a preference for 
standing trees, they will breed in win df alien trees and, more rarely, 
in 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 
woody 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 sap wood 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 arways 
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) Eegulate 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 
vicinity 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 of the succeeding 
June. The trees selected to be girdled should be sound and healthy 
and not less 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 base. 
A large percentage of dead spruce remains sound for a considerable 
period after being killed by these insects, and should be salvaged when 
1 IT. S. Department of Agriculture, Div. Ent. Bulletin 28; also U. S. Department of Agriculture Farmers' 
Bulletin 476. 
