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 

 centur}', 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 



