OTHER ANIMALS 673 



Domestic Animals. Among the domestic animals employed to 

 kill rats are dogs, cats, and ferrets. The value of good dogs as ratters 

 can hardly be appreciated by those who have had no experience with 

 animals trained for this work. Small Irish, Scotch, and Fox terriers, 

 when properly trained, are superior ratters. Cats become in 

 some instances valuable as rat catchers. However, it is often ques- 

 tionable whether the good that they accomplish in this direction is 

 not more than offset by their destruction of song birds. Ferrets are 

 inveterate foes of rats, and are used chiefly to drive the rodents from 

 their burrows or retreats, in order that they may be caught when they 

 are driven from cover. 



Fumigation. Rats may be destroyed in their burrows in the 

 fields by the use of carbon bisulphide by saturating some absorbing 

 material with this liquid, putting it in the burrow and closing the 

 opening. This method, however, is not effective in buildings, as the 

 vapor of carbon bisulphide is heavier than the air, and therefore 

 could not be depended upon to follow the various retreats of these 

 pests. (Dep. Agr. Biol. Sur. B. 33.) 



THE PRAIRIE DOG. 



The prairie dog loves sunshine and a dry atmosphere, ranging 

 easterly from the arid plains toward the prairies of the Mississippi 

 Valley. He is fond of rich vegetation, as is shown 'by his great destruc- 

 tiveness to alfalfa, grains and other crops ; but the luxuriant vegeta- 

 tion has not been sufficient to lure him from his home of the dry 

 land and the dry air. He is pre-eminently a social animal, living in 

 colonies which vary in extent from a few acres to thousands of square 

 miles. While colonies many miles in length and breadth are not 

 rare, yet most of these animals live in very much smaller colonies. 



Food. The principal food of the prairie dog is grass, chiefly the 

 bunch grass of the plains. In alfalfa fields, however, he becomes so 

 destructive that sometimes whole fields are practically destroyed. It 

 has been estimated that 32 prairie dogs will consume as much grass 

 as one sheep. The chief damage done by these rodents consists in 

 the loss of grains and other crops, and the danger to stock from 

 stumbling in the holes often amounts to a serious loss. 



Methods of Destruction. Numerous remedies have been tried. 

 Most of them have met with some measure of success, and a few have 

 proved available on a large scale. Large colonies extending over 

 many square miles in area present serious problems as to complete 

 extermination, while smaller colonies may be exterminated by pois- 

 oning or fumigating. There are several poisons that have been used 

 with fairly good success. 



Cyanide of Potassium. Cyanide of potassium kills quickly and 

 is an excellent poison, but on account of its odor is somewhat difficult 

 to administer. As the handling of this poison is dangerous to man, 

 it must be handled with great care. 



Strychnine. Strychnine is probably, all things considered, the 

 best and mast satisfactory poison known for the destruction of these 

 pcvts. Two ounces of strychnine is sufficient to poi-on a bushel .f 

 wheat. The strychnine sulphate should be dissolved in warm \\.itrr 



