EODENT PESTS' OF THE FAEM. 



15 



Poison for Richardson ground squirrels. — Mix 1 tablespoonfiil of laundry 

 starch in i teacup of cold water, and stir it into i pint of boiling water to make 

 it a thin, clear mucilage. Mix 1 ounce of powdered strychnin with 1 ounce 

 of powdered bicarbonate of soda, and stir the mixture into the hot starch, 

 making a smooth, creamy paste free from lumps. Stir in i pint of heavy corn 

 sirup and 1 tablespoonful of glycerin, and, finally, 1 scant teaspoonful of saccha- 

 rin. Apply to 20 quarts of oats, and mix thoroughly to coat every kernel. Each 

 quart of the poisoned grain should make 40 to 60 baits. Distrilrate in same 

 manner as stated for poisoning Columbia ground squirrels. 



Poison for California, or ''digger," ground squirrels. — Prepare by same formula 

 as for Richardson ground squirrels, but use 16 quarts of clean barley instead of 

 oats. Distribute as for poisoning Columbia ground squirrels. 



These poisons may be used at any time of the year when the squir- 

 rels are active. The Biological Survey has had excellent results with 

 them, even in mid- 

 summer. Trapping- 

 is too slow a process 

 to use effectively 

 against large colonies 

 of ground squirrels. 



PRAIRIE-DOGS. 



The prairie - dog ' 

 (fig. 11) of the Great 

 Plains needs little 

 description. It is 

 widely distributed on 

 the plains east of the 

 Rocky Mountains, 

 from northern Mex- 

 ico almost to the Ca- 

 nadian border. Sev- 

 eral other forms 

 occupy the mountain valleys and parks Avestward. All live in 

 thickly populated colonies, or "towns," and subsist on vegetation. 

 They often take fully half the pasturage on the ranges and greatly 

 reduce the carrying capacity for live stock (fig. 12). Several 

 Western States have attempted to provide for the extermination of 

 prairie-dogs through legislative enactments; and in some of them, 

 notably Kansas, the pest has greatly decreased. Within the national 

 forests settlers have complained of inabilit}^ to cope with the animals, 

 because their lands when freed from prairie-dogs are reinfested from 

 the surrounding Government lands. For this reason and for range 

 improvement the Department of Agriculture has undertaken sys- 

 tematic extermination work within the forests and has already suc- 

 ceeded in freeing large areas of these animals. 



Fig. 11. — Prairie-dog. 



^ Cynomt/s ludovicianus. 



