THE FOREST 193 



as a forest fire, but that in no way lessens the loss to the forest. 

 Such diseases as the chestnut blight, which arrived from the 

 Orient around 1901, proceeded in a few years to kill every 

 chestnut in the entire northeast forest region. Thus, one of the 

 most valuable of our hardwoods was practically exterminated. 



Between 1895 and 1919 in the Black Hills of South Dakota 

 and Wyoming a billion and a half board feet of yellow pine 

 was killed by the pine beetles. 10 Between 1921 and 1927, over 

 500 million feet of some of the finest virgin timber was killed 

 by these insects in the Modoc forest region in northern Cali' 

 fornia. These beetles, along with the spruce budworm, the 

 gypsy moth, and such fungi as white pine blister rust, cause a 

 tremendous amount of damage every year. Unlike fire, destruc' 

 tion by insects and disease is not so much a matter of careless' 

 ness. However, in regions that have been burned'over or in 

 stands heavily cut, the weakened trees are much more vulner' 

 able to both insects and disease. 



The Forest Service and the Bureau of Entomology and 

 Plant Quarantine in the Department of Agriculture are work' 

 ing to control these diseases with the aid of state foresters and 

 state agricultural colleges. The Department of Agriculture 

 through the same bureau tries to keep other insect pests out of 

 the country. All imports into the United States which might 

 carry new and dangerous timber diseases must pass the Plant 

 Quarantine inspection. This inspection was made necessary by 

 the fact that the majority of the dangerous tree diseases have 

 been imported from abroad. 



SOIL AND WATERSHED PROTECTION 



One of the direct effects of clear'Cutting timber is to leave 

 the soil exposed to the force of running water. In the section 

 on water we discussed the route of water by way of infiltration 



10 Ibid., p. 259. 



