INSECT ENEMIES OF WESTERN FORESTS 



149 



Figure 67. — Galleries and pupal cells of the emarginate ips (/. emarginatus) 

 on the inner bark surface of ponderosa pine. 



tops of lodgepole pine killed by Dendroctonus beetles. During se- 

 vere epidemics of the mountain pine beetle in lodgepole pine it 

 often develops in such numbers as to attack and destroy many 

 small trees. 



The adults are the smallest of the western species and are about 

 y 8 inch long. They are distinguished by having three small, spine- 

 like teeth along the margin of the elytral declivity, which is nearly 

 vertical. Its typical work consists of from two to five rather short, 

 sometimes curved, egg galleries radiating from the central nup- 

 tial chamber. It is distributed throughout most of the Western 

 States, where it attacks ponderosa, sugar, digger, lodgepole, Jef- 

 frey, Coulter, western white, and probably other pines. /. guildi 



