46 DEPARTMENTAL EEPORTS. 



OUTLINE OF WORK FOR THE YEAR 1901. 

 FIELD WORK. 



The plans for field work for the current year, as alread}^ stated, 

 comprise a continuation of the biological survey in California, a con- 

 tinuance of the Avork of outlining the life zones in Texas, a recon- 

 uoissance of the coast and islands of southern Alaska, and a recon- 

 noissance of the Hudson Bay region. In California, the main work 

 will be carried on in the Sierra between Lake Tahoe and the Yosem- 

 ite Valley. Some collecting will be done in the northern coast ranges 

 near Mount St. Helena to supplement the work of last season, and 

 also in San Mateo County, below San Francisco Bay. The work in 

 Alaska will be chiefly in the region between Cook Inlet and Unalaska. 

 Most of this field Avork was Avell under way at the beginning of the 

 fiscal year. 



DESTRUCTION OF PRAIRIE DOGS. 



The interest in the extermination of prairie dogs in some of the 

 States on the Great Plains, especially in western Texas and eastern 

 Colorado, emi)hasizes the importance of making a thorough iuA^estiga- 

 tion of the most economical method of destroying this i)est on the 

 ranges of the arid region. Preliminary experiments with gasoline, 

 strychnine, and bisulphide of carbon haA^e been made this season in 

 the Aacinity of Henrietta, Tex. GasMine is objectionable on account 

 of the time and trouble necessary in obtaining the materials, in prop- 

 erly applying it, and the danger in its use. In the strychnine experi- 

 ments, a formula recommended by Prof. A. T. Peters, of the Nebraska 

 experiment station, Avas used in preparing the poison. According to 

 this formula, 3 ounces of strychnine and half a pound of cyanide 

 of potassium are dissolved in a quart of boiling Avater; 2 quarts of 

 molasses and a teaspoonful of oil of anise are then added, and after 

 the mixture has been poured over 1 bushel of Avheat, 4 pounds of 

 finely ground corn meal are sprinkled OA^er it and well stirred in. A 

 tablespoonful of the poisoned Avheat should be scattered about the 

 entrance of each hole. Experiments with this preparation AA^ere tried 

 in summer on a tract scA^eral acres in extent, and about 50 per cent 

 of the prairie dogs AA^ere killed. The results Avould doubtless have 

 been more satisfactory if the experiment had been tried in Avinter or 

 early sirring when the animals first come out from hibernation and 

 before they find an abundant supply of food in the form of grass. 



Bisulphide of carbon j)roA'ed more satisfactorj^ than either gasoline 

 or strychnine, and is altogether the most efifectiv^e poison. A table- 

 spoonful of bisulphide properly applied to each occupied hole was 

 found suificient in tlie majority of cases to kill all the inmates, Avhile 

 if any Avere lef b a second application nearly always completed the 

 AA'ork. These experiments shoAV that the expense of extermination 

 by means of bisulphide, including the cost of material and labor, is 

 about 1 cent per hole. The number of occupied holes per acre in the 

 A'icinit}' of Henrietta aA^eraged between 20 and 30, which would make 

 the cost of extermination 20 to 30 cents per acre, as compared Avith 

 about 10 cents per acre AA^hen jDoisoned Avheat is used. In some locali- 

 ties the number of holes is estimated at 90 to 150, but it is doubtful 

 Avhether the occupied holes CA'er aA^erage more than 100 per acre, and 

 of course it is useless to apply bisulphide to any except those that are 

 occupied. 



