B. P. I.—46. V. P. P. I.—100. 
THE “BLUING” AND THE “RED ROT” OF THE WEST- 
ERN YELLOW PINE, WITH SPECIAL REFERENCE TO 
THE BLACK HILLS FOREST RESERVE. 
INTRODUCTION. 
The present investigation was undertaken to determine— 
(1) The cause of the blue color of the dead wood of the western 
yellow pine, commonly known as the bull pine (Pinus ponderosa), and 
the effect of the coloring on the value of the wood. 
(2) The reason for the subsequent decay of the wood, the rate of 
decay, and whether the decay could be prevented. 
(8) Whether it would be possible to use the dead wood before it 
decayed; first, to reduce the fire danger; second, to prevent the decay 
and thereby save an immense quantity of timber. 
DEATH OF THE TREES. 
The physiological changes which take place in the bull pine (Pinus 
ponderosa) as a result of the attack of the pine-bark beetle (Dendroc- 
tonus ponderose Hopk.“) are intimately connected with the fungus 
diseases under consideration, and may therefore be referred to briefly. 
According to Hopkins, the beetles enter the bark of the living trees 
in July, August,and September. The primary longitudinal burrows or 
galleries are excavated by the adult beetles, and the transverse, broad, 
or larval mines (Bull. 32, n. s., Division of Entomology, U.S. Depart- 
ment of Agriculture, Pls. I and III and fig. 1) through the inner bark 
and cambium of the main trunk have the effect of completely girdling 
the tree, and by September the cambium and the bark on the lower 
portion of the trunk are dead. The foliage of the trees thus attacked, 
however, shows no change from the normal healthy green until the 
following spring, when the leaves begin to fade. 
The first signs of disease noticeable in an affected tree are visible in 
the spring of the year following that of the attack by the beetle. Here 
«Hopkins, A. D. Insect Enemies of the Pine in the Black Hills Forest Reserve. 
Bull. 32, n. s., Division of Entomology, U. 8. Dept. of Agriculture, pp. 9, 10. 
i] 
