10 



4. In this series, as in the one reported in table 3, the mixture of 4 

 pounds of sodium fluosilicate and 100 pounds of bran gave the best 

 results, although the crude arsenic bait was only slightly less effective. 

 The crude arsenic, possibly because of its being less soluble, does not 

 seem to be so distasteful to the Mormon crickets as is the sodium 

 arsenite, but it should be used with caution on account of the danger 

 of poisoning grazing animals. The baits containing sawdust were again 

 well below the most effective mixture. 



Table 3.— Mortality of the Mormon cricket, including both nymphs ond adults, 

 as an index of the efficiency of baits containing different poisons and carriers, 

 Benteen, Mont., altitude 8,000 feet, 1989 



Poison 



Quantity 

 of poison 



Carrier > 



Average 2 

 kill (11 

 replica- 

 tions) 



Sodium fluosilicate ... ... . . 



Pounds 

 4 

 3 

 4 

 4 

 4 

 4 

 4 

 4 



Bran. 



Percent 

 90.6 



Do 



do 



88.5 



Sodium fluoride 



do 



86.9 



Sodium fluosilicate . 



Mill-run bran, sawdust (1:1) _ 



68.8 



do : 



Do 



Ground soybeans, sawdust (1 : 3) 



Mill-run bran, sawdust (1 : 3) 



Bran 



do 



63.5 



57.8 



Synthetic cryolite 



Calcium fluoride 



23.3 



16.3 



1 100 pounds in all cases. 



2 Standard error of any average, 5.48 percent. 



Minimum significant difference, 15.38 percent. 



Table 4. — Mortality of adults of the Mormon cricket as an index of the efficiency 

 of baits containing different poisons and carriers, Bear Lodge, Wyo., altitude 

 8,000 feet, 1939 



Poison i 



Carrier 2 



Average 3 

 kill (12 

 replica- 

 tions) 



Sodium fluosilicate 



Bran _ ..___.. - . . . 



Percent 

 93.4 



Crude arsenic 



do 



85.6 



Sodium fluosilicate 





80.6 



Do 





77.8 



Do 





74.3 









1 4 pounds in all cases. 



8 100 pounds of carrier in all cases. 



3 Standard error of any average, 3.49 percent. 



Minimum significant difference, 9. 86 percent. 



TIME AND TEMPERATURE FOR OPTIMUM FEEDING 



ON BAITS 



The effect of temperature and time of day on feeding and other 

 activities of the Mormon cricket were determined from counts obtained 

 from tests made by the pan-bait method. The results of 28 days' 

 observations on adult crickets made during July and August 1938 are 

 shown in figure 3. Figure 3, A, shows the number of crickets feeding 

 in relation to air temperatures both in the forenoon (ascending temper- 

 atures) and in the afternoon (descending temperatures). The opti- 

 mum temperature for feeding was found to be 86° F., although active 



