Five synthetic pyrethroids, phenothrin, cypermethrin, tralomethrin, fluvalinate and Pay-off, (( plus or minus )-cyano (3-phenoxyphenyl) methyl (+)-4-(diflouromethoxy)- alpha -(1-methylethyl) benzeneacetate), were tested for toxicity to larvae of the tobacco budworm, Heliothis virescens (F.), larvae of a predator, Chrysopa carnea Stephens, and adult males of a parasite, Campoletis sonorensis (Carlson). Tralomethrin was the most toxic to the pest and the parasite, but one of the least toxic to the predator. All these synthetic pyrethroids were less toxic to the predator than to the parasite and, except for phenothrin, were less toxic to the predator than to the pest. Based on their selectivity ratios, tralomethrin seems to be the most promising candidate of the pyrethroids tested for use in integrated pest management programs, provided C. carnea is the major natural enemy component in the ecosystem. none