68 SOME INSECTS INJURIOUS TO TRUCK CROPS. 



of them being found dead soon after spraying. Fortj^-three dead 

 larvpe were found in a furrow beside one plant which contained 29 

 dead hirva\ In another place 112 dead larvse were counted in 3 

 feet of furrow. 



RESUME OF EXPERIMENTS. AND CONCLUSIONS. 



Experiments 1, 2, 3, G, and 7, in which Paris green was used at the 

 rate of 5 to 8 ounces in 50 gallons of water, were failures because in 

 each case the rain which followed the application washed off the 

 poison. 



Experiments 4 and 9, in which arsenate of lead was used at the rate 

 of 2 pounds to 50 gallons of water, were also failures for the same 

 reason. 



Experiments 8, 10, and 11, in which copper arsenite was used at 

 a rate of from 10 ounces to 1 pound in 50 gallons of water, failed, 

 not because of burning the foliage, as was feared, but because the in- 

 sects were not killed. 



Experiments 5, 12, 13, 14, and 15, in which arsenate of lead was the 

 insecticide employed at the rate of 2 to 3 pounds in 50 gallons of 

 water, were successful in each case. 



The results of this series of fifteen experiments show conclusively 

 the superiority of a spray of arsenate of lead to one of Paris green 

 when applied under suitable conditions. It is in every way more 

 effective and more satisfactory than the latter, as Paris green is so 

 likely to be washed away by the frequent rains of the wet season of 

 Florida. These remarks apply practically to all cutworms, cater- 

 pillars, and other larvae which devour truck and related crops in 

 central Florida or similar regions. 



ADHESIVE COPPER ARSENITE MIXTURE. 



The preparation of copper arsenite used in the experiments that 

 have just been reported was stated by its inventor to be free from 

 soluble arsenious acid and to possess the adhesive properties found in 

 no other adhesive insecticide. It was stated to be composed of 36 

 per cent dextrin and 4 per cent gum and was prepared to be used in 

 conjunction with lime in the proportion of 1 part by weight to from 4 

 to C) parts of lime — either drj^ or in solution, according to the foliage 

 to be tested. The inventor also expressed his confidence that this 

 insecticide would prove a most economical one for general garden 

 and other use, as the loss by wind and rain would be reduced at least 

 50 per cent and the first cost of the article would be about half that 

 of Paris green or arsenate of lead. 



Samples of this mixture were submitted to Mr. J. K. Haywood, 

 Chief of the Miscellaneous Laboratory, Bureau of Chemistry, Avho 

 furnished the following analysis, August 7, 1907 : 



