112 



ELEMENTARY FORESTRY. 



ble, but with very high trees it is very difficult if not entirely 

 impracticable. 



Borers and Lice- These sometimes cause serious injury, but 

 it is seldom practicable to combat them successfully. It is 

 generally better to avoid them by planting- the kinds that are 

 least subject to injury from their attacks. Where lice are 

 injurious, kerosene emulsion or strong tobacco water are 

 good remedies. In the case of small trees that can be easily 

 enclosed in a tent, the best remedy is tobacco smoke. 



Figure 26. White Willow windbreak seriously injured by successive 

 attacks of saw fly larvae. A common source of injury to willows. 



Mice and Rabbits. Seedlings and small trees of some kinds 

 are liable to injury from rodents, such as mice and rabbits, 

 which gnaw the bark near the surface of the ground and per- 

 haps girdle the tree. They are most likely to do this whn 

 the ground is covered with snow, for this furnishes them with 

 a protection under which they can do their mischief without 

 fear of being molested. In the case of small seedlings such 

 injuries may be largely prevented by plowing a furrow or 

 setting boards on edge around the seed bed. If, after each 

 snow fall, the snow is trodden down so as to make a solid path 

 between the seedlings and the grass or woodland whence the 

 mice come, they will be kept out, as they will not try to work 

 through the solid snow. Seedlings that are badly girdled in 

 winter should be cut off at the surface of the ground to 



