CONTROL OF MORMON CRICKET WITH POISONED BAIT 7 



None of the baits containing these attractants gave materially 

 better results than the one containing only bran, water, and poison. 



EXPERIMENTS TO DETERMINE THE VALUE AND 

 MOST EFFICENT STRENGTHS OF DIFFERENT POISONS 



Tests were also conducted in 1936 to determine the best kind of 

 poison and the proper quantity for use in control of the Mormon 

 cricket. These tests were made at Pry or, Mont., at an altitude of 

 approximately 3,500 feet under conditions characterized by higher 

 temperatures and lack of moisture. One hundred pounds of bran and 

 12 gallons of water were used in all cases, and the mortalities shown 

 below are the averages of seven replications: 



Average 

 kill 

 Kind and quantity of poison (percent) 



Sodium fluoride, 4 pounds 94. 9 



Sodium fluosilicate, 4 pounds - 93. 3 



Paris green, 4 pounds 92. 2 



Sodium arsenite, 1 4 quarts 86. 1 



Crude arsenic, 5 pounds 81. 3 



Sodium arsenite, 1 2 quarts 79. 7 



Sodium arsenite, 1 1 quart 77. 8 



Sodium fluosilicate, 2 pounds 74. 5 



Standard error of any average, 2.83 percent. 

 Minimum significant difference, 8.00 percent. 

 1 32 percent AS2O3. 



This series of tests showed sodium fluoride, sodium fluosilicate, and 

 paris green to be the most effective poisons under the conditions of the 

 experiment, but the lower cost of sodium fluosilicate would recommend 

 it over the other two poisons for use in large-scale campaigns. The 

 bait containing 4 pounds of sodium fluosilicate was significantly more 

 effective than that with only 2 pounds, and it was better than any of 

 the sodium arsenite baits except that containing 4 quarts of the 

 poison. 



EXPERIMENTS BY THE WING-PEN METHOD TO COM- 

 PARE THE MORE PROMISING BAITS OF PREVIOUS 

 TESTS 



In 1937 the wing-pen method of collecting the crickets, in which the 

 insects had more liberty to feed on or reject the poisoned baits, was put 

 into practice, and with this more reliable index it was desired to test 

 again those bait combinations that had given the best results in 1935 

 and 1936. In addition to these a bait containing 2 gallons of black 

 distillate oil was tested. In all the baits 100 pounds of standard bran 

 was used as the carrier, moistened with 12 gallons of water. The 

 mortality figures are shown in table 1 . 



The sodium fluosilicate bait was outstanding in these tests. This 

 not only reflected the greater accuracy of the new method of collect- 

 ing the samples, but also indicated that sodium fluosilicate had a 

 distinct advantage over sodium arsenite as a killing agent in Mormon 

 cricket bait. The black oil distillate used in this bait was thought at 

 the time to be mainly responsible for the outstanding results. This 

 was disproved, however, in the tests of 1938. 



