136 PRINCIPLES OF AMERICAN FORESTRY. 



what weakened, and such trees may occasionally be left 

 as traps, and when badly infested burned, and in this 

 way large numbers of borers of some kinds may be 

 destroyed. Trees that are badly attacked should as a 

 rule be removed. 



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 perhaps girdle the tree. They are most likely 

 to do this when 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 pre- 

 vented by ploughing a furrow or setting boards on edge 

 around the seed-bed. If, after each snowfall, 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 generally be cut off at the surface of 

 the ground, to encourage sprouts from the roots. To pre- 

 vent the gnawing of larger trees, paint the tnmks with 

 a cement or lime wash made rather thick and containing 

 Paris green in the proportion of one tablespoonful of 

 Paris green to a pailful of the wash. If skim-milk is 

 used in mixing the wash, instead of water, the material 

 sticks better. Trees that are gnawed badly may often 

 be saved by coating the injured surface with grafting- 

 wax, blue clay, or other similar material, soon after the 

 damage is done, so as to prevent the seasoning of the 

 wood, and thus give it a chance to heal over. Where 

 the injury is close to the ground, it should be covered 

 with earth. 



The Pocket Gopher. Trees are sometimes injured 

 by pocket gophers eating the roots. Trapping or poison- 



