426 SOME FOUR-FOOTED PESTS OF THE FARM 



protect, instead of slay, the various animals which prey upon 

 them and hence are beneficial, though frequently referred to as 

 "vermin." 



Injuries caused by field mice are: Gnawing of orchard and 

 nursery trees and shrubbery close to or just beneath the surface 

 of the ground, usually during the winter season; the destruction 

 of various kinds of grain at harvest time; and occasional depreda- 

 tions in houses and barns into which they have gained entrance. 



In one case a very large per cent of young maple trees on three 

 hundred acres were killed by mice, the injury being discovered 

 after the snow had gone off. The owner of this tract began after- 

 ward to poison the offenders. Probably the injury to maples just 

 referred to is, in part, due to the killing off of birds of prey and 



FIG. 413. Field mice. (From Brehm.) 



four-footed animals that feed upon mice. It seems to be a com- 

 monly accepted idea that all hawks and owls must be shot. They 

 both work on field mice. Skunks and other small, four-footed 

 animals that prey upon mice are mercilessly destroyed as being 

 pests. It is by acts of this kind that the balance in nature is dis- 

 turbed and unpleasant results follow. 



Field mice are fond of wheat and rye, and injure timothy and 

 clover. It has been estimated that one adult field mouse may 

 consume, in one year, from twenty-four to thirty-six pounds of 

 green vegetation. They have at least one redeeming trait, for 

 they evidently eat a few insects, such as grasshoppers and beetles. 

 However, the slight good they do in this way is far more than 

 offset by their injurious work. 



The work of mice in an orchard can easily be distinguished 

 from that of rabbits. The latter gnaw higher up, and the marks 



