296 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 14 



From this table we find that 1^ lb. rate gave the best kill but the 

 1>^ lb. rate was only 1.2% below it. Because of this the lyi lb. strength 

 might well be recommended when crude arsenic is used in grasshopper 

 baits, although satisfa:;tory results were obtained from all strengths 

 above and including ^< lb. Only 4.9% of the check hoppers died dur- 

 ing the six day period in captivity. 



Rate of Application 



In determining the rate to apply poison bran mash to obtain the 

 best results, a series of experiments was planned whereby poison bran 

 mash was mixed with the various arsenicals at their optimum strengths 

 as determined above. Data were obtained by the method previous- 

 ly described. Each series of experiments was run in duplicate, the com- 

 bined results of which are shown in the following tables. 



Table V Paris Greex (Bait applied Sept. 21.). 

 Rate of application Total No. hoppers No. hoppers dying No. hoppers re- Percentage of kill. 

 (wet weight) swept 



149 

 186 

 187 

 16.3 

 192 

 197 

 20.3 



54.3 

 61.8 

 63.1 

 63.1 

 77.6 

 71.5 

 71.9 



5 lbs. per acre 

 Tyi lbs. per acre 

 10 lbs. per acre 

 12^ lbs. per acre 

 15 lbs. per acre 

 V7yi lbs. per acre 

 20 lbs. per acre 



Totals 1277 853 424 



It will be seen that the 15 lbs. rate gave noticeably better results 

 than any of the rest. The lower rates gave comparatively poor 

 kills in every case. 



In sweeping hoppers for the check cage in this series of experiments 

 a number of poisoned hoppers were included, due to some slight con- 

 fusion existing in the fields in which the experiments were conducted, 

 this also occurred in the experiments, the results of which are shown 

 in Table VI. Because of this the checks were omitted from these two 

 series of experiments. 



Table VI White Arsenic (Poison mash applied Sept. 3). 

 Rate of application Total No. hoppers No. hoppers dying No. hoppers re- Percentage of kill, 

 (wet weight) swept maining aliye 



