200 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



tions covered approximately 65 acres, very little choice could be found. 

 Apparently both worked with nearly the same rapidity and were 

 equally effective. The coarse grade of arsenious oxide was a little 

 hard to handle, making a very careful mixing necessary. The lack of 

 color also means that more care must be used to insure an evenly mixed 

 bait. Calcium arsenate was used in four experiments in direct com- 

 parison with both of the above, and in all four gave good results. It 

 was noted that it was not as rapid a poison as the others but the hop- 

 pers were made sick and apparently did no further injury. At the 

 end of the five-day period, however, the mortality resulting from each 

 of these three poisons was nearly the same. In treating tobacco, 

 Paris green caused some leaf burn while calcium arsenate did not. 



Rate of Application 



It was found in many cases, and especially so when there was any 

 amount of vegetation in the field, that the use of the standard poison 

 bait at the rate of 25 pounds for five to seven acres was not heavy 

 enough to secure maximum results. This appeared to be due to the 

 weakness of the odor of the standard bait. However, an addition of 

 lemon extract to the standard formula made a much more odorous bait, 

 and proved effective at the usual rate of application, while the standard 

 bait when used at the rate of from six to eight pounds to the acre, gave 

 efficient results. The use of lemon extract alone depends greatly 

 upon the strength of the extract. One extract which was tried, and 

 which did not give results, was found to be what was called a 2 per 

 cent extract. Druggists' extracts were found to be at least a 5 per 

 cent extract, and will run as high as 10 per cent. 



It appears that the rate of application should depend upon the 

 infestation and the attractiveness of the bait. 



THE VALUE OF CRUDE ARSENIOUS OXIDE IN POISON BAIT 

 FOR CUTWORMS AND GRASSHOPPERS^ 



By John J. Davis, West LaFayette, Indiana 



Last winter (January, 1918) Mr. W. R. Walton submitted samples of 

 a finely powdered crude arsenious oxide from a Montana copper smelter 

 company to determine its effectiveness against cutworms and grass- 

 hoppers when used in bran bait as a substitute for Paris green. It was 

 tested indoors with army worms (Cirphis unipuncfa) and the results 



1 Published by permission of the Secretary of Agriculture. 



