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



The patch of dead cambium heals over and leaves only a brown 

 pitch pocket in the wood to mark the place of injury. Some wood 

 sections have shown as many as seven such attacks during the 

 life of the tree, which indicates that a certain amount of activity 

 by this beetle is constantly going- on in the forest. Trees are at- 

 tacked during the summer months, and the eggs hatch and larvae 

 develop before winter. The winter is usually passed in the larval 

 stage, and the new broods emerge the following year. These beetles 

 normally have but one generation annually. Because of the spo- 

 radic character of outbreaks and the possible presence of healthy 

 broods in living trees no methods of control appear practical. 



Other species of Scolytus which may be found in western firs 

 include S. subscaber Lee, a large species which makes E-shaped 

 galleries in the limbs of white and red fir (fig. 74) ; S. praeceps 



Figure 74. — Scolytus subscaber: A, E-shaped galleries on limbs of white fir; 



B, adults, X 4. 



Lea, a small species about y 8 inch long, which attacks the limbs 

 and small tops of white fir and other firs in Oregon, California, 

 Arizona, and New Mexico; and S. monticolae (Sw.), about % 

 inch long, which is recorded by Swaine as attacking western white 

 pine and Douglas-fir in British Columbia, Washington, Oregon, 

 Idaho, Montana, and Wyoming. S. reflexus Blkm. attacks Douglas- 

 fir in Arizona and probably in other Southwestern States. 



