22 AN ECONOMIC STUDY OF FIELD MICE. 



The bliiegrass vole {M. p. aiiricularis) , a form with ears overtop- 

 ping the fur, which is' dark and glossy, occurs in southern Indiana 

 and in Kentucky, Tennessee, Mississippi, and Alabama. It has been 

 taken in northeast Texas also, so that its range probably extends 

 through southern Arkansas and connects the two areas. 



The woodland vole (J/, p. nemoralis) is the largest form of the 

 pine vole in America, and has longer and less gloss}" fur than the 

 forms east of the Mississippi. Its color is deep chestnut, darker 

 than typical pinetort/m, but lighter than ficalopsoides or auriodaris. 

 It occurs in wooded parts of southern Iowa, eastern Nebraska and 

 Kansas, and in Missouri, northern Oklahoma, and Indian Territory. 



Pine mice differ greatly in habits from the other species of M'tcro- 

 fus. All the American representatives of the group have similar 

 habits, and the injury they do to crops is little less in extent than that 

 inflicted by meadow mice and prairie mice. 



DAMAGE BY FIELD MICE. 



While field mice of the various groups differ but little in the 

 nature of their food, the circumstances under which they injure crops 

 vary. Meadow mice invade cleanly cultivated fields onl}" under the 

 shelter of snow. Hence they do most damage in years of great snow- 

 fall. Although prairie mice commit greater depredations under 

 cover of snow than in open seasons, their attacks upon crops are far 

 less dependent upon snowfall than those of meadow mice. Pine 

 mice work in the shelter of their own burrows; hence their injuries 

 to plants are quite independent of the amount of snow. 



i)a>ia<;e to :\rEADOAvs am) pasti res. 



Complaints of damage to meadows and pastures by field mice have 

 been increasing in recent years. Usually the injury is confined to 

 small areas, which the animals attack from the shelter of snoAvdrifts 

 or old grass. Under cover of these, the animals eat the succulent 

 crowns of clover and other grasses ; and when the snow lies for several 

 weeks the crops over large areas are often completely ruined. Some- 

 times whole fields of red clover are so badly damaged by mice that 

 they have to be replowed in the spring and planted to other crops. 



Damage to permanent, or uncultivated, meadows is usually more 

 serious, as the mice breed and multiply throughout the field and, 

 imder cover of the growing crop of leafy stubble, devour and destroy 

 throughout the year. Occasionally, however, actual benefit may re- 

 sult from their thinning the grasses and stirring the soil about the 

 roots. Thus, after the vole plague in Scotland in 1892, the farmers 

 reported that the pastures were better than before; but the improve- 

 ment by no means compensated for the losses caused by the impaired 

 pasturage of the two preceding years. 



