(Z,E)-9,11-tetradecadienal (Z9,E11-14: Ald; 11%), (Z,E)-9,11,13-tetradecatrienal (Z9,E11, 13-14: Ald; 67%), (Z,E)-9,11-tetradecadienyl acetate (Z9,E11-14: Ac, 5.5%), and (Z,E)-9,11,13-tetradecatrienyl acetate (Z9,E11,13-14: Ac; 16.5%) were identified in the extracts of female pheromone glands ofStenoma cecropia (Lepidoptera: Elachistidae). From electroantennograms and single sensillum recordings, receptors toZ9,E11,13-14:Ald andZ9,E11-14: Ald were found on male antenna. Behavioral data were obtained from olfactometric tests in the laboratory and field trapping experiments in Colombia. It appeared that a blend ofZ9,E11,13-14:Ald (83%) andZ9,E11-14:Ald (17%) was attractive to males. These aldehydes are assumed to be components of the sex pheromone ofS. cecropia, whereas the acetates found in gland extracts might be precursors of the pheromone.