142 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



nately such outbreaks die down at the close of the operation. Some- 

 times trees are killed the first year by the basal attacks of the 

 lodgepole pine beetle, or it may require 3 or 4 successive years of 

 attack before the resistance of the trees is sufficiently lowered to 

 render them attractive to other bark beetles. Other trees are 

 abandoned by the insects before the attacks prove fatal. In any 

 case, this basal damage to the tree may be considered as primary, 

 as it is the first weakening influence. 



The adults are about 1 4 inch long and have reddish wing cov- 

 ers, while the prothorax and head are dark brown or black. Their 

 attacks, which are made on stumps or on the boles of the trees, 

 usually within 4 or 5 feet of the ground, are easily recognized by 

 the large pitch tubes, an inch or more in diameter, which form at 

 the entrance holes. On reaching the cambium the attacking beetles 

 construct short egg galleries, ranging from 5 to 12 inches or more 

 in length, directly between the bark and wood. Eggs are deposited 

 along the sides of these galleries and are separated from one an- 

 other by boring dust. The larvae feed away from the egg gallery, 

 keeping together in a common excavation or brood chamber. There 

 are no separate or individual larval mines. Transformation to 

 pupae and new adults takes place in cells constructed in the un- 

 eaten part of the inner bark or in cocoonlike structures composed 

 of excrement in the brood chamber. The seasonal history has not 

 been thoroughly worked out, but there appears to be one genera- 

 tion a year. Outbreaks of this insect are seldom of sufficient eco- 

 nomic importance to warrant control measures. 



The red turpentine beetle {Dendroctonus valens Lee.) (fig. 64) 

 {Jf3, 60) attacks the base of injured, dying, or healthy trees, or 

 freshly cut logs and stumps of all pines and occasionally spruce, 

 larch, and fir, throughout the western and northeastern parts of 

 the United States and southern Canada. Ordinarily it is not con- 

 sidered an aggressive tree killer but it does do considerable pri- 

 mary damage and so weakens trees as to make them more 

 susceptible to attack by other bark beetles. In some infestations, 

 as in Monterey pine in California, it causes sufficient damage to 

 kill the tree. It is particularly active around logging operations, 

 where it not only works in the stumps, but often produces catfaces 

 on the bases of trees left in the reserve stand. 



The adults are the largest bark beetles of this genus, measuring 

 from % to % inch long, and are distinctly reddish in color. They 

 are often called barber beetles by woodsmen, because of their 

 ability to clip hairs, and are commonly, though erroneously, 

 thought to be the bark beetles responsible for the destruction of 

 pines. Their attacks are characterized by large reddish pitch tubes 

 that form at the point of attack. On burrowing under the bark, 

 the beetles excavate irregular longitudinal egg galleries between 

 the bark and the wood. These galleries range from a few inches to 

 several feet in length, as Patterson reports finding one gallery 

 extending underground along a root for 15 feet from the point of 

 entrance. The galleries are more or less packed with frass, and 

 eggs are laid in groups or masses at intervals along the sides. The 

 larvae feed out through the inner bark in mass formation, produc- 



