-3- 



The intensity of synergism was not very great for any of the effec- 

 tive materials. The effect was to raise toxicity to about 1.7 that expected 

 for allethrin alone. This effect was obtained with the following synergists, 

 all being among the higher disubstituted ethoxybenzamides: 



N - Diamyl - p - ethoxybenz amide 



N-Dibenzyl-p-ethoxybenzamide 



N-Dibutyl-p-ethoxybenzamide 



N - Butyl - 4 - ethoxybenzanilide 



4-Ethoxy-N-ethylbenzanilide 



p -Ethoxy-N- diisopropylbenzamide 



p-Ethoxy-N-dipropylbenzamide 



This intensity does not reach that of the best synergists for allethrin 

 as determined by the same m.ethod, piperonyl butoxide and sulfoxide. In 

 mixtures of similar proportion the effect with each of these was to raise 

 toxicity to about three times that expected for allethrin alone.—' 



3/ Gersdorff, ^^' . A., and P. G. Piquett. A comparison of cyclethrin, 

 allethrin, pyrethrins, and mixtures of piperonyl butoxide or sulfoxide 

 with them in house fly sprays. Jour. Econ. Ent. (in press). 



