100 



MISC. rUBLICATIOX 273, U. S. DEPT. OF AGRICULTURE 



Direct control is recomniendecl. particularly during developing epi- 

 demic conditions. The control measures consist in felling the infested 

 trees; peeling and burning the bark late in the fall, or in winter or 

 early spring: or peeling and spreading the bark for destruction of 



FiGrRE 48. — Work of the western pine beetle {Dendroctoniis hrevicornis) : A, Egg galler- 

 ies on inner bark (half size) ; B, an infested tree trunk with bark removed (drawing 

 by DeYoung) ; C, 1 year's loss in a ponderosa pine stand in California. 



the broods by solar heat during the summer months. Control work 

 has been successful in reducing infestations during critical periods, 

 but cannot be relied on to eliminate them, and must be repeated until 

 natural control factors become operative. 



The sotithwestern pine beetle (Denti'octonus harheri Hopk.) attacks 

 ponderosa pines in southern Colorado, southern Utah. Arizona, and 

 Xew Mexico. A preference is shown for trees over 6 inches in diam- 



