those of the natural component. In addition to the racemic mixtures of I (6-methyl-2-octadecanone) and II (14-methyl-2-octadecanone), previously synthesized, the activity of III was evaluated in the Iriomote Islands, and effective male attraction was observed for the 2:1:1 mixture of I-III. This result indicates that the females do not produce only one stereoisomer for each component or that the response