THE GENUS DENDEOCTONUS. 
65 
EFFECTS ON COMMERCIAL VALUE OF THE WOOD. 
The commercial value of the wood of trees killed by this beetle is 
reduced by the bluing of the sap wood (fig. 29), often before the leaves 
begin to turn yellow, though the heartwood, especially of the larger 
spruce and yellow pine, usually remains sound for many years after 
the trees die; both the sap and heart wood of the smaller trees, and 
even of the large pitch, loblolly, and Table Mountain pine, deteriorate 
rapidly (figs. 26, 27), and 
therefore must be utilized SSff^T 
immediately after the Jg* . ^T 
trees begin to die, in order 
to save anything of com- 
mercial value. 
Serious losses of a sec- 
ondary nature, both of 
dead and adjoining living 
timber, may result from 
fires started in the dead 
timber. Therefore the 
prompt utilization of the 
beetle-infested trees and 
the prevention of forest 
fires are important to ob- 
viate total destruction of 
the timber. 
FAVORABLE AND UNFAVOR- 
ABLE CONDITIONS FOR THE 
BEETLE. 
Favorable conditions 
for the multiplication and 
spread of the beetle are 
found in areas of large, 
matured timber and 
where the trees are fre- 
quently struck by light- 
ning, felled, or injured by 
storms, etc., during the 
summer months. 
g^^te^^^SgL^tt^ 
Fig. 27.— A forest of Table Mountain pine, Mineral County, 
W. Va., seven years after it was killed by the southern 
pine beetle. (Original, from photograph.) 
The odor from the exposed wood, and perhaps from the wilting 
foliage of a few trees cut in the midst of a healthy growth of pine dur- 
ing the summer, serves to attract this species, apparently from a long 
distance, and to induce attack on the surrounding healthy trees. 
Therefore, any irregular or sporadic local cutting of timber for fuel 
or any limited purpose during the summer months furnishes most 
89535— Bull. 83, pt. 1—09 6 
