RODENTIA 285 



in Labrador they furnish plenty of food for wolves and thus tend to 

 lessen the destruction of stock and game. 18 It is also well known that 

 the world's fur markets are affected by the relative abundance of mice, 

 which furnish food for the furbearers. 19 



"Meadow mice choose a somewhat varied diet, but their food con- 

 sists mainly of green vegetation, roots and bark. Grass, especially the 

 tender base of grass stems, forms the bulk of their food, but almost 

 every plant with which they come in contact is eaten to some extent. 

 Bark, both from roots and trunks of trees and shrubs, is a favorite 

 winter food. Seeds and grain are eaten when found, but are not es- 

 peciaily sought; flesh in any form is never refused.'* 2 



Although usually classed "among the most destructive rodents that 

 the farmer has to contend with . . . under ordinary conditions these mice 

 are useful as destroyers of noxious weeds and grasses of no agricul- 

 tural value." 21 However, the constant levy upon crops, especially hay 

 and forage crops, day by day throughout the year, must aggregate a 

 very large loss, in addition to damage to orchards. Ten field mice in 

 captivity for thirty days ate an average of 55 per cent of their own 

 weight in food daily, which feat they could equal under natural condi- 

 tions where food is abundant and they are leading a more active ex- 

 istence, to the aid of their digestion. Hence only 10 mice to the acre 

 on a loo-acre meadow would take 1 1 tons of grass or 5^ tons of hay 

 per annum ; or, on the 65,000,000 acres of hay raised in the United 

 States, may cause a loss of 3,000,000 tons of hay, or a monetary loss 

 of $30,000,000, per annum. 22 



In a seed-beet silo, field mice destroyed the crowns of 90 per cent 

 of the beets. 23 They are known to destroy many snails, 24 but probably 

 do no harm and no good in that way. In 1903-1904 they did great 

 damage to orchards and nurseries in Kansas and Missouri, and in 

 1901-1902 did damage to the estimated extent of $100,000 to nurs- 



* Allen, Journ. Mammalogy, in, 56-57, 1922, citing Cabot's Labrador. 

 18 Hewitt, Conservation of the wild life of Canada, pp. 214-215, 1921. Innis, The 

 fur trade of Canada, pp. 90-91, 1927. 



20 Bailey, Revision of the American voles of the genus Microtus, N. Amer. Fauna, 

 No. 17, p. 6, 1900; N. Amer. Fauna, No. 49, p. 91, 1926. 



21 Burnett, Meadow mice, Office Colorado State Entom. } Circular No. 18, p. 5, 

 1916. 



22 Bailey, Breeding, feeding and other life habits of meadow mice (Microtus), 

 Journ. Agric. Research, xxvii, 532, 1924. 



23 Burnett, Rodents of Colorado in their economic relations, Office Colorado State 

 Entom., Circular No. 25, p. n, 1928. 



24 Pilsbry and Bequaert, Bull. Amer. Mus. Nat. Hist., mi, 497, 1927. 



