Abstract: cis-Jasmone has been discovered to be useful as a semiochetnical that changes the behaviour of insects and/or the physiology of plants. It has direct signalling roles with plant-feeding aphids, in attraction of aphid predators and parasitoids, and may act as an airborne signal inducing production of volatile plant semiochemicals, including the monoterpene (E)-?-ocimene, that stimulate foraging by parasitoids. It is an extremely benign compound having, to human beings, a pleasant aroma and gives a long-lasting effect after removal of the stimulus.