44 



279. The Yellow-Pine Wood Engraver { rHyogmes carinulatus Liec.) . 



A secondary enemy of pine. Attackn branches and twigs of trees dying from 

 attack of the pine-destroying l)eetle. 



Exhibit: Adults; work of adults and larv;e in bark and surface of wood. 



280. The Oregon Tomicus {Tomicus orego7ii YAch.). 



A secondary enemy of jiine forests in the Black Hills, attacking the larger l)ranciies 

 and upper portions of the trunks of trees injured by or dying from an attack of the 

 pine-destroying beetle. Occasionally a primary enemy of living trees. 



Exhibit: Adults; galleries of Oregon Tomicus and iiine-destroying beetle side l)y 

 side in bark of pine; work of adults in l)ark; groovings in surfaci' of wood. 



DESTRUCTION OF PINE FORESTS BY BARK-BEETLES IN THE 



SOUTHERN STATES. 



CA.SE 50. 



281. The Destructive Pine Bark-Beetle {Dcndrodonus frontalis TAram.) . 

 Attacks healthy pine and spruce in the Southern States. It is capable of enor- 

 mous destruction and, though usually held in check by natural causes, has at various 

 times past so increased as to seriously menace the entire stand of pine and spruce in 

 portions of the Southeastern .States, notably in West Virginia in 1891-92. 



Exhibit: Adults; markings on surface of wood of beetle-killed tree; appearance of 

 outer bark and surface of wood of beetle-killed tree; section of trunk of pine, show- 

 ing galleries of adult beetles in bark two to three weeks after first attack, surface of 

 wood marked by galleries of adult beetles and mines of larvpe six to eight weeks 

 after attack, outer bark of tree scaled off by woodpeckers in search of beetles and 

 their larva?; work of adults and larv;e in bark. 



282. The Companion Bark-Beetle {Tomicus aridsns Eich. ). 



A common species infesting pine in the Southern States. When abundant it may 

 attack and kill healthy trees, but is especially common as a secondary enemy in 

 company with the destructive pine bark-beetle. 



Exhibit: Adults; apj^earance of work of adults and larva? in bark; galleries of 

 destructive pine bark-beetle and companion Ijark-beetle side by side in bark of large 

 beetle-killed tree. 



DESTRUCTION OF WESTERN YELLOW PINE BY BARK-BEETLES 

 IN THE SOUTHERN ROCKY MOUNTAIN REGION. 



C^SE 51. 



283. The Arizona Dendroctonus {Dendroctonns n. sp. ). 



A common bark-beetle in the southern Rocky IMountain region attacking healthy 

 western yellow pine, and in company with several closely allied species causing 

 destruction of large quantities of the best timber. 



Exhibit: Adults; work of adults and larvre in bark. 



284. The Colorado Dendroctonus (Dendroctonus appro.rimatus Dietz). 

 Attacks recently-dead and living western yellow pine in the southern Rocky 



Mountain region. Often found working in the same tree and side bj' side with the 

 Arizona Dendroctonus. 



Exhibit: Adult; surface of wood showing marks of work; gallery of adult and 

 mines of young larva in Ixirk. 



285. The Pine-Destroying Beetle of the Black Hills {Dendroctonus povderosse 

 Hopk.). . 



Exhibit: Adults; surface of wood showing characteristic groovings; gallery of 

 adult and mines of young larva? in bark. 



