8 



CIRCULAR 5 7 5, U. S. DEPT. OF AGRICULTURE 



Table 1. — Mortality of the Mormon cricket as an index of the efficiency of baits con- 

 taining different poisons and attractants, Billings, Mont., 1937 



1 Carrier, 100 pounds bran, 12 gallons water. 



2 Standard error of any average, 4.4 percent. 



Minimum significant difference, 12.58 percent. 



Poison i 



Attractant 



Average 1 

 kill (9 



replica- 

 tions) 





Percent 

 Black distillate, 2 gallons 87. 32 



Sodium arsenite, 2 quarts 



Do 



Cane molasses, 2 gallons; amyl acetate, 3 60.52 



ounces. 

 None 59.36 



Do 



Cane molasses, 2 gallons... . .. - . 



52.91 







EXPERIMENTS TO DETERMINE FURTHER THE VALUE 

 OF THE ATTRACTANTS AND THE MOST EFFICIENT 

 STRENGTHS OF SODIUM ARSENITE AND SODIUM 

 FLUOSILICATE 



The experiments of 1938 were designed to test, by means of the 

 wing-pen method, the value of two attractants, cane molasses and oil, 

 when used with sodium fluosilicate, and also to determine how small 

 a quantity of sodium fluosilicate would give the maximum kill. The 

 sodium arsenite bait used in all previous tests was also included for 

 comparison. The results are given in table 2. 



Table 2. — Mortality of the Mormon cricket as an index of the efficiency of baits 

 containing attractants and different quantities of poison, Benteen, Mont., 1938 



Poison ' 



Average - 

 Attractant ™A?_ 



tions) 



Sodium fluosilicate, 4 pounds 





Percent 

 89.3 



Do 





86.3 



Do 



Black distillate, 2 gallons 



. do 



83.9 



Sodium fluosilicate, 2 pounds . _ _ . 



79.7 



Do 



None 



None 



75.2 



Sodium arsenite, 2 quarts 



41.8 







1 Carrier, 100 pounds bran, 12 gallons water. 

 J Standard error of any average, 2.84 percent. 



Minimum significant difference, 



percent. 



The results shown in table 2 prove conclusively that sodium fluo- 

 silicate is far superior to sodium arsenite as a killing agent, even when 

 used at the rate of only 2 pounds per 100 pounds of bran. Two 

 pounds of fluosilicate, however, was decidedly less efficient than 4 

 pounds. The mortality obtained with the bait containing cane 

 molasses was not significantly higher than that obtained with the one 

 containing oil or the one containing no attractant, and according to 

 these figures the added cost of the molasses in baits for large-scale 

 use is not warranted. 



These results were further substantiated by pan-baiting tests 

 covering a period of 28 days in which the sodium arsenite bait was 

 fed upon by only 2.8 percent of the total number of crickets feeding, 



