44 



279. The Yellow-Pine "Wood Engraver (Pityogenes carinulatus ~Lec.) . 



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

 attack of the pine-destroying beetle. 



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



280. The Oregon Tomicus ( Tomicus oregoni Eich. ). 



A secondary enemy of pine forests in the Black Hills, attacking the larger branches 

 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 pine-destroying beetle side by 

 side in bark of pine; work of adults in bark; groovings in surface of wood. 



DESTRUCTION OF PINE FORESTS BY BARK-BEETLES IN THE 



SOUTHERN STATES. 



CASE 50. 



281. The Destructive Pine Bark-Beetle (Dendroctonus frontalis Zimm.). 

 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 larvae six to eight weeks 

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

 their larvse; work of adults and larva? in bark. 



282. The Companion Bark-Beetle (Tomicus avulsus 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; appearance of work of adults and larvse in bark; galleries of 

 destructive pine bark-beetle and companion bark-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. 



CASE 51. 



283. The Arizona Dendroctonus (Dendroctonus n. sp.). 



A common bark-beetle in the southern Kocky Mountain 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 larv?e in bark. 4 



284. The Colorado Dendroctonus (Dendroctonus approximatus Dietz). 

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



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

 Arizona Dendroctonus. 



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

 mines of young larva in bark. 



285. The Pine-Destroying' Beetle of the Black Hills (Dendroctonus ponderosx 

 Hopk.). 



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

 adult and mines of young larvre in bark. 



