428 YEARHOOK OF TllF. DKPAKTMENT OF AGRICULTURE. 



birds, particularly if carefully placed close to the mouths of the 

 burrows. As a medium for conveying the poison there is little doubt 

 that alfalfa, either green or dr}^, will prove equally or even more 

 successful, and it has the advantage that it is not eaten by birds. 



One and a half ounces of strychnia sulphate is enough to prepare 

 a bushel of wheat. Dissolve the strychnine in a quart of boiling 

 water and add a quart or more of thick sugar sirup. Pour this 

 mixture over the Avheat in a clean metal vessel and stir until all the 

 wheat is wet. Stir in corn meal to take up any surplus moisture, 

 if the poison is to be used immediately, or add more Avater and 

 leave the wheat to absorb the strychnine over night. Many expe- 

 rienced persons prefer the latter plan, but the writer has been 

 equally successful Avith both. About a teaspoonful of the poisoned 

 Avheat is placed at the mouth of each occupied burrow. It is impor- 

 tant to choose a time Avhen the animals are both active and hungry, 

 preferably in Avinter or early spring. 



The Kansas formula. — A feAv years ago the State of Kansas car- 

 ried on extensiA^e operations against prairie dogs, destroying them 

 almost completely oA-er nearly 2,000,000 acres of thickly infested land. 

 The poison Avas prepared at the State agricultural college experiment 

 station, and for more than three years the Avriter had charge of its 

 preparation and distribution. It was sold to townships and indi- 

 A^iduals at cost, or the formula for preparing it was given to citizens 

 of the State who asked for it. The formula Avas adapted from one 

 patented by David W. Staples, formerly of Quanah, Tex.« The 

 State purchased the right to use the poison, but the writer found 

 the formula impractical for large operations and it was modified into 

 the following: 



For 1 gallon poisoned sirup, use — 



4 ounces powdered stryclinia sulphate; 



4 ounces potassium cyanid ; 



4 ounces green coffee; 



6 ounces alcohol ; 



4 eggs (whites only) ; 



i gallon thick sugar sirup. 

 Preparation. — Mix the coffee and whites of eggs, and let the mixture stand 

 OA'er night. Dissolve the cyanid of potassium in a little less than a quart 

 of hot water, and let it cool before using. Prepare the sugar sirup previously, 

 so that it is not hot when used. Pour the cyanid of potassium solution over 

 the coffee-and-egg mixture, stir, and then strain into the mixing vessel 

 through a sieve fine enough to hold the coffee, which is rejected. Add the 

 sugar sirup and stir thoroughly. Dissolve the strychnia in a little less than 

 a quart of boiling water. Pour the alcohol into this solution and stir. Then 

 add the mixture of strychnine, alcohol, and water to the contents of the mixing 

 vessel and stir thoroughly. 



« Patent No. 456602, issued July 28, 1891. Expired July 28, 1908. 



