No abstract

The 6-chloropiperonyl esters of d-trans•, dl-trans-, dl-cis-, and dl-cis-trans-(barthrin) chrysanthemumic acid were synthesized. These esters and the l-trans ester (by inference) were, respectively, 62, 38, 29, 32, and 14% as toxic to houseflies (Musca domestica L) as allethrin at the 50% mortality level. At the 95% mortality level the ratios were one third greater. Year-old sprays of barthrin were just as toxic as sprays from a freshly prepared sample. The knockdown values of barthrin and the three isomers, although excellent at highly toxic concentrations, were much inferior to that value of allethrin at comparable concentrations.