126 



SCIENCE 



[N. S. Vol. XLVI. No. 1180 



spring of 1915-16, were so severe that in 

 some instances no less than three plantings 

 of corn had to be made." A serious out- 

 break occurred during 1916 in the province 

 of Foggia in Apulia, Italy,' where the grain 

 crop is reported to have been almost en- 

 tirely destroyed by inordinate increase of 

 voles of the genus Pity my s; and in the fer- 

 tile Shenandoah valley, Virginia, where a 

 thriving fruit industry is conducted, mice 

 belonging to the same genus have become 

 so abundant and so troublesome during the 

 spring of 1917 that in some orchards they 

 have girdled and killed seventy-five per 

 cent, of the trees.' 



That the steady drain upon our agricul- 

 tural products caused by. various noxious 

 rodents over a large part of the country 

 when present in normal numbers is of even 

 greater consequence to our agricultural 

 welfare than the damage from plagues has 

 already been emphasized by Lantz.^ Some 

 idea of the extent of this damage may be 

 gained from the following figures, gathered 

 recently by the chief of the Biological Sur- 

 vey. 



The annual loss to grain crops through 

 the agency of ground squirrels in North 

 Dakota on the basis of present prices is 

 estimated by authorities at the State Ex- 

 periment Station to aggregate more than 

 $6,000,000. 



A. E. Bowman, director of the State 

 Agricultural Extension Service, Wyoming, 

 ■states that 15 per cent, of the crops within 

 that state are destroyed annually by 

 rodents. 



The annual losses from rodents in the 

 state of Kansas are placed at $12,000,000. 



The department of biology of the Mon- 

 tana Agricultural College estimates that 

 the crops in that state suffer annual losses 



« Reported by Professor B. E. Lautz, Biological 

 Survey. 



T Nature, Beeember 28, 1916, p. 338. 

 8 Biol. Surv. Bull. 31, 1907, p. 8. 



through ravages of rodents amounting to 

 $15,000,000 to $20,000,000. 



These are isolated reports concerning a 

 situation which is general ; a conservative 

 estimate places the probable losses to agri- 

 culture from noxious native rodents in the 

 western and Pacific states alone at more 

 than $100,000,000 annually. 



In 1909 fire losses and losses to grains 

 and other merchandise due to European 

 rats and mice were estimated to aggregate 

 $59,917,000 annually." Assuming that the 

 amount of damage done by these rodents is 

 approximately the same now as then, it is 

 not improbable, at present prices of grain 

 and other merchandise, that the annual 

 losses will aggregate at least $100,000,000. 

 Suggestions made by CreeP" and Forbush^^ 

 indicate that even this figure may be far too 

 low. The former estimates that each rat 

 costs one half a cent per day, or $1.82 per 

 year, to feed ; and the latter calls attention 

 to the fact that on the basis of Creel's esti- 

 mate, assuming that the rat population is 

 the same as the human population, the an- 

 nual cost to the country is $182,000,000; 

 and both these suggestions were made when 

 the price of wheat was less than half what it 

 is at present. 



The cogency of these facts is more than 

 ever apparent during the present growing 

 season. Weather conditions have been un- 

 favorable, labor is scarce and the winter 

 wheat crop is reported to be the shortest 

 in years. All practicable steps should be 

 taken, not only to increase acreage, but to 

 guard against local or general plagues of 

 insects or rodents, and to cut down to the 

 minimum the enormous losses which hereto- 

 fore have occurred continuously. The sav- 

 ing of grain which will be effected through 



s C. Hart Merriam, Kept. Nat. Conservation Com- 

 mission, Vol. 3, pp. 339-340. 



10 U. S. Public Health Eeports, 28, 1913, p. 1405. 



11 Bull. No. 1, Econ. Biol., Mass. Board of Agri- 

 culture, 1915, p. 25. 



