Pyrethroid microemulsion compositions and method for controlling insects therewith

A stable pyrethroid microemulsion composition comprising:

• (1) from 0.1% to 95% by weight/weight of at least one synthetic pyrethroid in liquid form:
• (2) from 2% to 90% by weight/weight of a surfactant system comprising:
• (a) at least one anionic surfactant selected from the group consisting of neutral phosphates or sulfates of ethoxylated, propoxylated or ethoxypropoxylated di(1-phenylethyl)phenols and ethoxylated, propoxylated or ethoxypropoxylated tri(1-phenylethyl) phenols;
• (b) at least one nonionic surfactant selected from the group consisting of ethoxylated, propoxylated or ethoxypropoxylated di(1-phenylethyl)phenols, ethoxylated, propoxylated, propoxylated or ethoxypropoxylated tri(1-phenylethyl)phenols and ethoxypropoxylated nonylphenols;
• and
• (c) at least one co-surfactant selected from the group consisting of straight-chain or branched aliphatic alcohols having from 3 to 10 carbon atoms, cycloaliphatic alcohols having from 5 to 12 carbon atoms, arylaliphatic alcohols having from 7 to 12 carbon atoms, ether-alcohols of the formula R-(OR').sub.n -OH, wherein R represents a straight-chain or branched alkyl radical having from 1 to 8 carbon atoms;
• R' represents an alkylene radical;
• and n represents an integer from 1 to 3;
• and straightchain or branched aliphatic carboxylic acids having from 5 to 10 carbon atoms;
• and
• (3) water;
• wherein the ratio by weight of anionic surfactant/nonionic surfactant is from 10.90 to 90/10, and the ratio by weight of cosurfactant/anionic surfactants is from 0.25 to 0.80.