THE EXTERMINATION OF THE PRAIRIE DOG 97 



2. GREGARIOUS OR VERY ABUNDANT ANIMALS. 



(a) The prairie dog is 'locally abundant. The poisoning of 

 these pests is comparatively such a simple task that no one need 

 have a town near his land unless he is too lazy to get rid of it. 

 Large towns have been entirely destroyed by one application of 

 poisoned food done properly and at the right time. 



The poisons found most satisfactory, and recommended by 

 the Biological Survey of the Department of Agriculture are (i) 

 Sulphate of strychnine. Care should be taken to secure strych- 

 nine sulphate since the strichnine usually sold by druggists is in- 

 soluble in water. One and one-half ounces of strychnine sulphate 

 to a bushel of grain is sufficient. The strychnine should be 



;ved in 2 1-2 gallons of water by heating in a covered re- 

 ceptacle. After thoroughly dissolved, add the grain and allow 

 to stand over night. The grain will absorb the liquid. In dis- 

 tributing the grain, one-half teaspoon full should be put just 

 outside of each hole, and had better be distributed during the 

 evening hours. 



(2) One ounce of strichnine sulphate dissolved in one gal- 

 lon of water mixed with green alfalfa or green, growing grain 

 cut in lengths of 2 to 4 inches and distributed in the evening so 

 that it may be eaten before it is dried by the sun, is usually en- 

 tirely successful. 



(3) Crude bisulphide of carbon suitable for killing burrow- 

 ing animals costs about 8 cents per pound in 50 pound carboys 

 or drums. It is a volatile liquid and hen.ce should be kept tightly 

 corked. It is highly explosive. A tablespoonful of crude bisul- 

 phide should be poured in a piece of dried horse manure, corncob 

 or other absorptive material and this should be thrown as far as 

 possible down a burrow into which a prairie dog has just disap- 

 peared. The burrow should be immediately closed. Bisulphide 

 can be used to best advantage after a heavy rain. 



It should be clearly understood that the method recommended 

 by the government consists of two steps (i) to destroy the great 

 bulk of the inhabitants of the colony by poisoning with strychnine 

 in \vinter or early spring when food is scarce; (2) to kill the re- 

 maining animals with bisulphide of carbon. In this way it is be- 

 lieved that colonies of any size may be wiped out at a total cost of 

 not to exceed 16 or 17 cents per acre, probably less. 

 Sig. 7. 



