The major sex attractant emitted by Scrobipalpuloides absoluta females is shown to be (3E,8Z,11Z)-3,8,11-tetradecatrien-1-yl acetate by a novel strategy involving the random reduction of double bonds, followed by methylthiolation of the reduced products. Each female sex gland contains ca. 1-5 ng of this pheromone. This triene ester, synthesized by a stereospecific procedure, shows spectral and gas chromatographic properties identical to those of the natural substance. In field tests and wind tunnel bioassays, the synthetic ester was found to be highly attractive to conspecific males. The male response to this pheromone, however, is restricted to the same early-morning time window during which females exhibit calling behavior.