32 AMERICAN FORESTRY 



METHODS OF EXTERMINATION 



The United States Biological Survey has for several years past tried 

 various uiethods of exterminating the prairie dog. It has decided that the 

 most effective and economical methods to employ are poisoning with barley 

 roots soaked in strychnine, and suffocating through the introduction of bi- 

 sulphide of carbon into the burrows. About one-half teaspoonful of the 

 poisoned bait scattered on the hard ground at the mouth of a burrow is 

 sufficient. When the bisulphide of carbon is used it is placed upon some 

 absorptive material and thrust as far into the burrow as possible and then 

 the entrance of the burrow is closed. If the bulk of the animals are de- 

 stroyed by poisoning with strychnine in spring or winter when food is scarce, 

 and the remaining animls subsequently treated with bisulphide of carbon, 

 whole towns can be destroped at a cost of not more than 16 or 17 cents per 

 acre, probably less. Other baits that may be used are green alfalfa, green 

 stems of young wheat or barley, and green corn stalks. 



Besides the extensive efforts of the Biological Survey, the praires dogs 

 are fought by the Forest Service. Large areas of natural cattle range are 

 within National Forests, and every effort is being made to put these ranges 

 in perfect condition; hence efforts are made to get rid of both prairie dogs 

 and predatory animals. Some persons believe that the decrease in the number 

 of wolves and coyotes has caused an increase in the number of prairie dogs, 

 a nice balance of nature having been destroyed. It is true that the most 

 inveterate enemies of the prairie dog are the wolf, the coyote, the badger, and 

 the rattlesnake. This list would make one want to take the side of the prairie 

 dog if one could choose between him and his enemies. But the prairie dog is 

 always the eaten, never the eater. 



Not much has been done as yet; there is not money enough to pay for 

 the material and labor required. However, the work of locating the towns 

 is complete, and this is one of the most important steps in the work. Such 

 work as the Forest Service has been able to do has been slow but sure. The 

 poisoned grain method has been used almost invariably. 



Following is the formula perfected and recommended by the Biological 

 Survey : 



STARCH-STRYCHNINE FORMULA FOR COATING GRAIN 



Barley, clean grain, free from other seeds 20 quarts 



Strychnia sulphate (ground or powdered) 1 ounce 



Saccharine 1 teaspoonful 



Gloss starch (ordinary laundry starch) V^ teaspoonful 



Water 11/2 pints 



Dissolve the starch in a little cold water and add V/2 pints of boiling 

 water, making a rather thick solution. While hot, stir in the strychnine and 

 mix until free from lum])s; then add the saccharine and beat thoroughly. Now 

 pour the ])oisonod starrli over tlie barley and stir ra])i(lly until the ])oison is 

 evenly distributed; then allow the grain to dry. When dry it will keep indefi- 

 nitely without deterioration. 



For ordinary quantities a galvanized-iron washtub is an excellent re- 



