45 



field ant, equivalent to 29.3 nests to the mile or 207 to the acre — a case 

 of moderate infestation only. The substances selected for special trial 

 in this field were those which had been found most offensive to ants 

 in the laboratory experiments of Dr. Tanquary, already described in 

 this paper. Choice was finally made of tincture of asafetida and oil 

 of tansy, applied to bone meal to be dropped with the corn by an at- 

 tachment to the corn-planter known as a fertilizer-dropper. The bone 

 meal was used at the rate of 100 pounds per acre, and was treated 

 with the repellents as follows : Where oil of tansy was used, a quarter 

 of a pound of the oil was added to two quarts of alcohol and a quart 

 of water, the fluids being then well stirred into the hundred pounds 

 of the bone meal so as to mix the whole mass thoroly. The alcohol 

 soon evaporated, leaving the oil of tansy well distributed thru the 

 bone meal. The procedure with the tincture of asafetida was the same, 

 except that the bone meal was treated with two pints of this fluid 

 diluted with one and a half gallons of water. 



Plots containing 3,520 to 5,060 hills each — that is 32 to 46 rows 

 wide and 1 10 hills long — were planted May 12 with each of these sub- 

 stances, and similar plots were planted beside them, one with corn 

 accompanied by plain bone meal and the other with no addition to the 

 seed. 



At husking time the yield of 1,800 hills taken from the twenty 

 central rows of each plot was separately weighed, with the result that 

 a considerable difference was shown in favor of the plots which had 

 received the repellent treatment. The untreated plot yielded at the 

 rate of 26.2 bushels; that of the bone meal plot, 26.6 bushels; 

 the bone-meal-asafetida plot, 31.8 bushels; and the oil of tansy plot, 

 'h7 bushels. The gain was practically nothing for the application of 

 plain bone meal, was 5.6 bushels for the use of asafetida, and 10.8 

 bushels for the use of oil of tansy. The cost of materials in these ex- 

 periments was $1.90 for the asafetida plot, and $2.95 for the oil of 

 tansy plot, the increase in the yield of the first being thus obtained at 

 34 cents a bushel, and that of the second at 27 cents. The general re- 

 sult of this experimental change in the method of applying repellents 

 at planting was the more encouraging because the gains above reported 

 were made during a year quite unfavorable to corn owing to the very 

 poor stand obtained. Cool weather after planting delayed germina- 

 tion and gave moles, mice, gophers, and insects an unusual opportunity 

 to devour the seed before it had started to grow. However, as it was 

 impossible to separate the loss due in these unusual conditions from 

 that attributable to infestation by root-lice, no exact estimate of re- 



