Insecticidal activity of the pyrethrins and related compounds. Part XI. Relative potencies of isomeric cyano‐substituted 3‐phenoxybenzyl esters

The insecticidal activities to Musca domestica L. and Phaedon cochleariae Fab. of a series of 3‐phenoxybenzyl pyrethroid esters with a cyano substituent at the 2‐, 6‐. ( R )‐α‐, or ( S )‐α‐position are compared with those of the unsubstituted analogues. Only an ( S )‐α‐substituent enhances activity; others diminish or almost eliminate it. ( RS )‐α‐mixtures are generally less active than would be predicted from the potencies of their separate constituents.