CONTROL OF MORMON CRICKET WITH POISONED BAIT 9 



while the fluosilicate-molasses bait was fed upon by 34.6 percent, the 

 fluosilicate-oil bait by 31.1 percent, and the plain flue-silicate bait by 

 30.5 percent. This would indicate that sodium arsenite, when used 

 in bait, is distasteful to Mormon crickets, and further pan-baiting tests 

 were conducted to determine the smallest quantity of sodium arsenite 

 that would make the bait unattractive. 



Six baits were prepared to compare 4 different strengths of sodium 

 arsenite used with 100 pounds of bran with a mixture of bran and 

 water alone and also with 4 pounds of sodium fluosilicate to 100 pounds 

 of bran. There were in all 369 crickets feeding in this test, and the 

 percentages feeding on the various baits were as follows: 



Percentage of 

 Bait total crickets 



feeding 



Bran and water (no poison) 47. 7 



Sodium fluosilicate, 4 pounds 38. 4 



Sodium arsenite, 2 quarts 2. 9 



Sodium arsenite, 1 quart 2. 5 



Sodium arsenite, 1 pint 4. 2 



Sodium arsenite, ){ pint 4. 2 



Unfavorable weather conditions terminated the experiments at the 

 end of 4 days; and although the results cannot be taken as conclusive 

 because of the limited number of observations, they indicate that even 

 a small amount of sodium arsenite is distasteful to Mormon crickets. 



EXPERIMENTS TO COMPARE NEW CARRIERS AND 

 POISONS WITH THE BEST BAITS OF PREVIOUS TESTS 



Additional experiments were designed in 1939 to test again the 

 effectiveness of various poisons and carriers by using the wing-pen 

 method of collecting the samples of crickets. Several of these had been 

 tested by the closed-pen method, but the results were not considered 

 conclusive. 



Two series of experiments were made; the first, including both 

 nymphs and adults, was conducted at an altitude of about 3,000 feet, 

 as were most of the earlier experiments. The second series included 

 only adults, and this was conducted at about 8,000 feet altitude. At 

 this altitude the vegetative cover differed considerably from that at 

 3,000 feet, the temperature was lower, and the soil moisture greater. 

 The conditions here probably represented about the least favorable 

 conditions for successful tests with baits. For these two reasons — 

 the stages of the insect represented and the effects due to the altitude — 

 the two series are presented separately, although two of the baits 

 appear in both. The results of the first series are given in table 3. 



The mortality associated in table 3 with the bait consisting of 4 

 pounds of sodium fluosilicate and 100 pounds of bran is only slightly 

 higher than that obtained with 3 pounds of the same poison. Sodium 

 fluoride was only a little less effective, but synthetic cryolite and 

 calcium fluoride were far below these in the list. It is of interest that 

 the three baits in which sawdust made up a portion of the carrier are 

 in effectiveness well below those with the standard bran alone, but they 

 showed little or no difference among themselves. 



The second series of experiments, in which adults only were used 

 and which was conducted under adverse conditions, is detailed in table 



235604—40 2 



