Pheromone gland extracts of codling moth females were examined by gas chromatography coupled with mass spectrometry and electroantennography. Nine compounds elicited antennal activity: the main pheromone compound codlemone (E,E)-8,10-dodecadienol, the E,Z and Z,E isomers of codlemone, codlemone acetate (E,E)-8,10-dodecadienyl acetate, codlemone aldehyde (E,E)-8,10-dodecadienal, the monounsaturated alcohols (E)-8-dodecenol and (E)-9-dodecenol, and dodecanol. In wind tunnel experiments, addition of dodecanol, the E,Z isomer of codlemone and codlemone acetate augmented male attraction to codlemone at the proportions found in female glands. Larger amounts of the E,Z isomer of codlemone and codlemone acetate had a strong antagonistic effect on male attraction. The identification of pheromone synergists in codling moth is of importance for the development of pheromone- based control methods.