A PLAGUE OF MICE 



481 



The shortage of hay 

 on the Rodger s ranch, 

 where 2,200 acres 

 were in alfalfa, was 

 estimated at 2,000 

 tons. On Anker's 

 ranch of 650 acres it 

 was estimated at 600 

 tons- Other ranches 

 suffered in proportion, 

 and the loss of hay in 

 the valley amounted 

 to not less than $50,- 

 000. W. C. Pitt, who 

 farms 1,400 acres of 

 alfalfa, estimates his 

 complete loss at $20 

 per acre, or $28,000. 

 John Font estimates 

 his damage on 1.000 

 acres at $20,000, and 

 Mr Anker considers 

 his loss on 650 acres 

 to be $8,000. Mr 

 Webb, on the Rodgers ranch, figures the 

 complete loss on 2,200 acres, part of 

 which pays considerably short of the best 

 returns, at $30,500. 



A careful consideration of the losses 

 in hay, pasturage, root crops, and trees, 

 the expense of restoring alfalfa fields to 

 their former condition, and deducting the 

 value of a grain crop for 1908 shows 

 the average loss to be about $20 per acre. 

 On this basis the damage to the valley 

 amounted to $300,000. 



Simultaneously with the plague in the 

 lower part of Humboldt Valley mice ap- 

 peared in enormous numbers farther up 

 the Humboldt River and its tributaries 

 about Winnemucca, Battle Mountain, and 

 in Paradise and Little Humboldt valleys. 

 As the lands infested in those districts 

 Avere chiefly great natural hay meadows 

 of red top and wild clover, the damage 

 was less severe. However, gardens and 

 isolated alfalfa fields were seriously in- 

 jured. Later, reports of mice in alarm- 

 ing abundance were received from King 

 River, Quinn River, and Carson and 

 Smith valleys, Nevada ; from Weber 

 River Valley and from Sanpete and 

 Utah counties, Utah, and from Honey 

 Lake Valley, California. In none of these 



Photo from Stanley E^. Piper, U. S. Biological Survey 

 LOMBARDY POPLAR GIRDLED AND KILLED BY FIELD MICE 



localities was the damage so extensive 

 as in Humboldt Valley, though plagues 

 of like severity were plainly threatened. 



PLAGUE AVERTED IN CARSON VALLEY BY 

 THE U. S. BIOLOGICAL SURVEY 



On learning of severe damage by mice 

 in Carson Valley, a hundred miles south- 

 west of Lovelocks, in April, 1908, the 

 U. S. Biological Survey sent several as- 

 sistants to the valley to check the threat- 

 ened plague. Carson and Humboldt 

 valleys are alike in having large areas in 

 alfalfa bordered by desert lands, on which 

 field mice do not live. On a tract of 

 about 2,500 acres near Minden mice 

 were found to be excessively abundant, 

 and in some fields 10 to 25 per cent of 

 the alfalfa plants had already been de- 

 stroyed. Several smaller centers were 

 similarly affected, while over the valley 

 generally the mice were somewhat in ex- 

 cess of normal numbers. This was a 

 condition similar to that presented in 

 Humboldt Valley during the spring of 

 1907, and young of all sizes were abun- 

 dant. Examination of many females, a 

 large percentage of which were pregnant, 

 showed an average of from 6 to 7 young, 

 while in a number as many as 10 were 



