PROTECTION FROM OTHER AGENCIES 311 



the bark, numerous pitch tubes, and fine boring-dust at 

 the base of the tree, all of them indications of the work 

 of bark-beetles. 



It was a species of bark-beetle that caused the so- 

 called spruce blight which has appeared in the red spruce 

 forests of the Northeast from time to time during the last 

 century, and which in certain sections caused the death 

 of most of the mature spruce. It was another species of 

 bark-beetle which has been devastating the forests of the 

 Black Hills in South Dakota. 



Still another species of bark-beetle destroys annually 

 an untold number of trees in the pine forests of the 

 Southeast. To-day this insect constitutes one of the 

 greatest menaces of the pine timber of the South, unless 

 provision is made to prevent the development of an in- 

 vasion. 



One of the most serious present outbreaks is located 

 in eastern Oregon in the Wallowa and Whitman National 

 Forests. Previous to 1903 only a few isolated areas of 

 less than a section each were infested. There was no 

 check to the spread of the insects, and in 1910 the inva- 

 sion has spread over about one million acres, having 

 already killed 35 per cent of the lodge-pole pine in 

 addition to a large amount of yellow pine. Unless the 

 invasion is checked the damage will amount to hundreds 

 of thousands of dollars. 



Extensive injury is also done by defoliating insects. 

 When a tree is defoliated only once, it is not necessarily 

 killed. If it is thrifty, it may produce leaves again the 



