348 AXNUAI. REPORTS OF UKPARTMENT OF AGRICULTURE. 



(jperations (liirin<2: tlic last foui- years have shown that tlie worst of 

 these pests, as prairie (lo<;s. certain species of <2;roiin(l s(|vurrels, and 

 pocket frophers, can be eradicated from a fjreat part of the fanninjz: 

 and l)est fora<re-pi-<)ducinfr re<rions of the West at a cost which is 

 merely nominal as compared with the annual increase in the pioduc- 

 tion of tlie land. The lar<;e and constant h' o;i-owin<r expenditure of 

 funds and application of labor by cooperating farming and stock- 

 raising conmiunities are conclusive evidence of the practical char- 

 acter of these campaigns. Under the modem methods of the bureau, 

 the first time the rodents are poisoned over a large area from 85 to 

 98 per cent of the animals are killed. This accomplished, follow-up 

 measures to complete the work are organized as needed during the 

 same and subsequent seasons. 



PUAIRIK DOGS AND GEOUKD SQUIRRELS. 



Prairie dogs and ground squirrels are the most widespread and 

 conspicuously destructive rodents affecting cultivated crops and 

 range grasses in the States west of the Mississippi River. They 

 do their damage by digging out the planted seeds and cutting down 

 the growing grain until harvested, by eating off alfalfa, clover, 

 bean, pea, and similar legume and hay crops, and by feeding on 

 forage grasses and digging out their roots, thus destroying the stand. 

 Lands thus denuded of native grasses are often subject to serious 

 erosion, resulting in permanent damage to the soil. Prairie dogs 

 occur from Texas north to North Dakota and Montana and from 

 Kansas west to Utah and Arizona. Ground squirrels of several 

 species live in vast numbers over all of the States west of the Missis- 

 sippi River, involving all of the area occupied by prairie dogs, but 

 becoming most conspicuously destructive in the Northern and West- 

 ern States, including the Dakotas, Montana, Wyoming. Idaho, north- 

 ern Utah and Nevada, Washington, Oregon, and California. 



The plans of organization, the seasonal work, and the methods of 

 extermination for eradication campaigns against both these groups 

 of rodent pests are essentially the same. The details differ some- 

 what, however, both wnth respect to the species concerned, the sea- 

 sonal, weather, and crop conditions, and the topography of the 

 country. The local representatives of the Biological Survey care- 

 fully observe and study these features and apply the measures which 

 have proved most effective and economical. 



Particularly notable results are now being secured on a large scale 

 in the campaigns against prairie dogs in NeAV Mexico and Arizona. 

 An illustration of this w^ork is furnished in one especially valuable 

 range area in Sulphur Springs A^alley. Cochise County, Ariz., a 

 tract 12 miles long and 4 miles broad, involving 30,700 acres, which 

 was completely cleared of prairie dogs last spring. Adjoining range 

 occupants then appealed to the inspector in charge to assist them in 

 conducting the work over their areas, with the result that by June 30 

 three-fourths of the area in both Cochise and Graham Counties Avas 

 completely cleared of prairie dogs. Work to clear the remaining 

 portions of these counties is progressing rapidly. The progress made 

 in eradicating a very heavy infestation of prairie dogs froni the 

 valuable range areas of Moreno Valley, northern New^ Mexico, is an- 

 other good example of the advance which is being made in the or- 



