16 



FARMERS' BULLETIN 932. 



Trapping is too slow a method for exterminating prairie-dogs, and 

 fumigation is too expensive. As in the case of ground squirrels, 

 strychnin has proved to be the most satisfactory poison. Oats of the 

 best quality obtainable should be used as bait. It has been found 

 that prairie-dogs take this grain readily, even when green food is 

 abundant. Wheat is well adapted for winter poisoning, and in the 

 South, where heavy oats are rarely obtainable, milo or feterita is an 

 excellent substitute. 



Poison for prairie-dogs. Mix thoroughly 1 ounce of powdered strychnin 

 (alkaloid) and 1 ounce of common baking soda (bicarbonate). Dissolve 1 

 heaping tablespoonful of dry laundry starch in a little cold water and add it 



FIG. 12. Erosion following the destruction of grass by prairie-dogs. 



8 1 4233 



to f pint of boiling water. Boil and stir until a thin, clear paste is formed. 

 Slowly sift the mixture of strychnin and soda into the starch paste, stirring 

 constantly to form a smooth, creamy mass. Add % pint of heavy corn sirup 

 and 1 tablespoonful of glycerin, and stir. Add A ounce of saccharin, and again 

 stir thoroughly. Pour this mixture while still hot over 13 quarts of clean oats 

 and mix until all the grain is coated. 



If ' alkaloid strychnin is not available, the sulphate may be used, either 

 powdered or in crystals, but it is necessary to vary the formula. Dissolve 

 the strychnin in the boiling water before adding the cold starch. After the 

 poisoned starch paste is clear, stir in the soda very slowly. Then add the 

 sirup, glycerin, and saccharin as in the above directions and mix w r ith the grain. 



For mixing small quantities an ordinary metal washtub is convenient. For 

 large quantities a tight, smooth box may be used, and the mixing done with 

 a hoe or spade. 



