84 RODENTS OF IOWA 



Meadow mice inflict considerable damage in parks and lawns by 

 destroying shrubs, vines, bulbs and herbaceous plants. In some 

 cases the straw or grass used to protect delicate plants in winter af- 

 fords shelter and hiding places for the animals. Low hedges also 

 afford shelter under which the mice construct their burrows. 



Meadow mice are not, for the most part, inhabitants of waste 

 lands, but of more or less cultivated regions; and in consideration 

 of their food habits as above described they must be considered as 

 injurious. That they are, to a slight extent, valuable as tillers of 

 the soil and as destroyers of noxious seeds cannot be denied, but 

 the slight good done in this way is more than offset by their destruc- 

 tive qualities. An invasion of these mice into an agricultural com- 

 munity would cause disastrous results, so that preventive and con- 

 trol measures should be continually encouraged and engaged in. In 

 view of the fact that the meadow mouse is so widely distributed, 

 that its habitats are usually inaccessible in ordinary control meas- 

 ures, and that the species is so prolific, complete extermination is 

 impossible. However, the numbers may be materially reduced in 

 any locality, so that crops may be rendered comparatively safe from 

 serious attacks. 



There are a number of natural agencies which cannot be left out 

 of consideration in the repression of meadow mice. In this con- 

 nection Lantz says : * ' Climatic conditions so strongly influence the 

 natural increase of field mice that an understanding of their re- 

 lation to such increase is important. It has often been noticed that 

 the period of greatest abundance of voles follows one or more open, 

 warm winters succeeded by wet summers. If at the same time food 

 particularly grain is abundant, the most favorable conditions 

 for the increase of the animals are present, and the maximum num- 

 ber of young at a birth, as well as the maximum number of litters, 

 are brought forth. When grain is abundant the young of rome 

 species are said to begin to reproduce when only 2 months old. 



"The continuance of favorable conditions for two or more years 

 is sure to be followed by an enormous increase of field mice, with 

 serious injury to crops. 



* ' Very cold winters without snow and summers of long droughts 

 are unfavorable to the increase of field mice. Occasionally a severe 

 frost following a heavy downpour of rain destroys nearly all field 

 mice over large areas." 16 



"Lantz, D. E., An Economic Study of Field Mice : U. S. Dept Agr., Biol. Surv. 

 Bull. No. 31, 37, 1907. 



