The olfactory response of female Oriental Fruit Moth, Cydia molesta, to several synthetic blends derived from peach shoots was assessed in Y-tube olfactometer bioassays. Both the levels of responsiveness and preference of mated females increased substantially as the complexity of the odor blends was increased. One chemical compound present in minute amounts in some of the blends evaluated was found to be crucial in eliciting appropriate behavioral responses by the female moths