COMMON MAMMALS OF WESTERN MONTANA. 



7 



tion with Mr. W. V. King, of the Bureau of Entomology, to whom 

 he is indebted for many of the data concerning the host relations of 

 the ticks, as well as for many observations on the distribution and 

 habits of the mammals treated herein. 



POISONING RODENTS. 



Poisoning is in many cases the most effective and least expensive 

 means of destroying harmful rodents; but methods of poisoning to 

 be successful must be carefully worked out with reference to par- 

 ticular kinds of animals and localities. The formulas given in this 

 bulletin should be closely followed, as the amounts of poison recom- 

 mended have been carefully determined. 



SOME COMMON RODENT POISONS. 



Strychnine, arsenic, and phosphorus are the three most generally 

 used rodent poisons. The following is a brief summary of the char- 

 acteristics of each : 



Strychnine is a vegetable poison obtained from the bean of the nux 

 vomica tree, the chief supply coming from the Malabar coast, India. 

 The strychnine of commerce consists of colorless crystals or white 

 powder, and there are two forms commonly used as rodent poisons — 

 the alkaloid and the sulphate. The alkaloid is only slightly soluble 

 in water, and in rodent poisons is usually powdered and applied to 

 grain in a coating of starch or flour paste. The sulphate dissolves 

 readily in either hot or cold water and is used in solution. Both are 

 deadly and act very quickly, causing tetanus, convulsions, and a 

 speedy and comparatively merciful death. The bitterness of strych- 

 nine is the chief drawback to its use, because ground squirrels, chip- 

 munks, and some other rodents refuse to eat bitter baits when their 

 natural food is plentiful. The addition of saccharine to strychnine 

 baits has formerly been recommended, but recent experiments have 

 shown that it does not conceal the bitterness of the poison, and is 

 therefore of little value. Although an expensive poison, strychnine 

 is so powerful that it is on the whole more economical than arsenic or 

 phosphorus, and its use is strongly recommended by the department. 



Yellow phosphorus is extensively used as a poison for ground 

 squirrels, rats, prairie dogs, and other rodents. But although it is 

 both cheap and effective, the great personal danger accompanying 

 its use and the fact that it causes a painful, lingering death are 

 such serious objections that the Department of Agriculture strongly 

 advises against its use. 



White arsenic is an almost tasteless, insoluble, rather weak, and very 

 cheap poison, used extensively in rat baits. Its action on rodents is 

 variable and uncertain. It often causes vomiting, and small doses 



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