Insect Enemies of Trees 211 



trees by some of these insect pests, the following cases may 

 be mentioned : 



During fifteen years (between 1853-68) the spruce in East 

 Prussia, Poland and Russia was killed over an area of 7,000 

 square German miles ; while in the Bavarian forests, the 

 loss to the Revenue in one year was 40,000. 



In both cases the destructive insect Liparis monacha was 

 the cause of injury. 



