DAMAGE TO FOOD SUPPLY BY MAMMALS 3Q 



lations is probably more serious, though less spectacular and therefore 

 more likely to escape notice. 



The field or meadow mice of the United States are not ordinarily 

 considered very serious pests, though they are abundant in many lo- 

 calities and doubtless require a very large quantity of grass and other 

 vegetation to sustain them. By their injury to pasturage they may 

 to some extent affect our meat supply. In the neighborhood of orchards 

 and nurseries they often inflict much damage by gnawing and girdling 

 the trees, thus also indirectly affecting our food supply more or less. 

 The damage done to nursery stock by these rodents at Rochester, New 

 York, in 1901-1902, was estimated at $100,000 while in 1920 they 

 injured 1500 trees in one orchard and 1000 in another; and in 1918 

 a mouse plague in one New York county did damage estimated at 

 $200, ooo. 11 In a field mouse plague in Nevada in 1907-1908 it was 

 estimated that there were 8000 to 12,000 mice per acre, resulting 

 in an almost total loss of the alfalfa crop, even the roots being eaten, 

 necessitating the re-seeding of 15,000 out of 20,000 acres, 12 the loss 

 of the alfalfa affecting the human food supply, in a very indirect, in- 

 tangible way and perhaps to a slight degree, but none the less certainly. 

 This is also true of the destruction of 90 per cent of the crowns of 

 beets in a Colorado seed-beet silo. 13 The white-footed mice or deer 

 mice are more generally distributed and do considerable damage, espe- 

 cially to grain in the shock. 



Kangaroo rats are much more local in distribution than either field 

 or deer mice, but where they occur they are sometimes very abun- 

 dant and destructive to grain and vegetables. Half a bushel of peas 

 and other seeds have been found in a single burrow. 14 These rodents 

 eat the seeds of important forage grasses, sometimes storing as much 

 as twelve pounds of seeds in a single den, and denuding the ground 

 of vegetation within a radius of from fifteen to twenty-five feet about 

 their burrows. 15 In fact, any small species of rodent is a potential pest, 

 as it may become overabundant during favorable seasons and hence 

 destructive. 



u Lantz, An economic study of field mice, U. S. Blol. Surv. Bull. No. 31, 1907. 

 Silver. Motive control in field and orchard, Farmers' Bull., No. 1397, 1924. 



12 Piper, The Nevada mouse plague of 1907-08, Farmers' Bull, No. 352, 1909; Year- 

 book U. S. Dept. Agric. for 1908, pp. 301-310. Bailey, Farmers' Bull., No. 335, 1908. 



13 Burnett, Office of Colorado State Entomologist Circular No. 25, 1918. 



14 Burnett, Office Colorado State Entomologist Circular No. 25, 1918. 

 "Taylor, Scientific Monthly, xxi, 2, 1925. 



