(E)-11-Hexadecen-1-yl acetate and (E)-11-hexadecen-1-ol were identified in extracts from the abdominal pheromone gland of femaleSceliodes cordalis and in a 1∶1 ratio acted as a potent field attractant for males. Sustained upwind flight by males to this mixture in a wind tunnel confirmed the identity of these compounds as major components of the natural sex pheromone of this species. The synthetic pheromone was used to define the annual limits of male flight activity. In the presence of 1-10 μg of pheromone per liter of air, the mating rate of laboratory populations was halved. TheZ isomers of both pheromone components decreased the numbers of males captured in traps baited with virgin females in the field and inhibited upwind flight in the wind tunnel. The attraction of males ofMnesictena flavidalis to virgin females ofS. cordalis and synthetic mixtures was demonstrated to be due to the acetate component alone. MaleEudonia sp. nrlinealis were captured by (Z)-11-hexadecen-1-yl acetate.