58 EXPERIMENT STATION RECORD. 



destruction varying from 90 to 99 per cent. Each formula was tested twice 

 on 100 burrows known to be occupied, the effect being determined by plugging 

 the holes of the burrows within a few days after the distribution of the grain, 

 as in case the prairie dogs were still alive the burrows would be opened within 

 a week. Two formulas showed an efficiency of 99 per cent, the one most easily 

 and quickly prepared and recommended by the author being the Colorado 

 formula, recommended by Johnson in a circular previously noted (E. S. R., 28, 

 p. 450). Directions given for its preparation are as follows: "Dissolve 1 oz. 

 of powdered strychnin alkaloid (for which we substituted strychnia sulphate), 

 one-half teacup of starch, and 1 teaspoonful of saccharin in 1 qt. of boiling 

 water. Pour it over 12 qts. of grain (barley, wheat, or oats), which is held in a 

 tight vessel, as a galvanized iron tub (which should subsequently be scrubbed 

 clean). Stir the mixture very thoroughly until every grain receives a thorough 

 coating, then spread the gi'ain out to dry. It will keep indefinitely. Sprinkle 

 on the mounds of the occupied burrows." 



Spring tests were made between February 12 and April 1.5 of five of the ten 

 formulas above mentioned, including the two which gave the best results. The 

 formulas tested were found to rank in the same order of efficiency as in the 

 fall, the first application giving results wliich varied from 53 to 77 per cent, the 

 second application an efficiency of to 28 per cent. In a demonstration of the 

 results that could be obtained on the range from the use of the most effective 

 formula, an extensive distribution of it resulted in the destruction of 75 to 80 

 per cent of the prairie dogs. The author's observations as well as those of 

 others indicate that there are few birds killed by the exposure of the poisoned 

 grain. 



Fumigation experiments with carbon bisulphid led to the conclusion that 0.5 

 fluid ounce of this chemical is insufficient for the dosage of the average prairie 

 dog burrow, since not over one-half of the animals succumb to such a treat- 

 ment, but that 1 oz. is a sufficient dosage to kill from 80 to 100 per cent of the 

 animals. An increase in dosage to 1.5, 2, or 2.5 oz. did not consistently add to 

 the effectiveness of the fumigation. When the soil is moist from recent rains 

 good results follow the simple careful pouring of the ounce of carbon bisulphid 

 into the burrow, but it is thought tliat the most consistently satisfactory 

 results will follow the use of the chemical on dry corn cobs. A test made of 

 mixing carbon bisulphid with gasoline indicates that 1 oz. of pure carbon bisul- 

 phid is more effective than is 1 oz. of carbon bisulphid mixed with 1 oz. of 

 gasoline. 



A list of 2.3 references to the subjo<^t is appended. 



The insectivorous habits of the mole in British Columbia, R. C. Tkeiiekne 

 {Agr. Gas. Canada, 2 {1915), No. 3, pp. 216, 217).— The two species here 

 referred to which occur in the Lower Fraser Valley are Scapanus townsendi 

 and Xciirotrichus (fibhsi, the latter being the more common. The author con- 

 cludes that the insectivorous liabits of the mole in British Columbia are Im- 

 portant aids to the farmer in the control of .soil-infecting insect pests, and that 

 unless moles are present in exceptional numbers, their good points in all 

 probability outnuniix-r the bad. 



The muskrat (Fiber zibethicus) and its ravages in Bohemia. O. Haempel 

 (Umfichau, IS (19JJ,), Xo. 4S, pp. 970-973, figs. 4; abs. in Intcnwt. Inst. Agr. 

 [Rome], Mo. Bui. Agr. Intel, and Plant Diseases, 6 (1915), No. 2, pp. 320, 321).— 

 The muskrat, four pairs of which were imported eight years ago from Canada 

 to Dobrisch, Bohemia, and liberatetl. has increased to an extraordinary extent 

 and become the source of much destruction and is also increasing in other parts 

 of Austria and Central Europe. Its fur has gradually doterioratoil since its 

 introduction into Bohemia so that tanners now refuse the skins. 



