Sex pheromones in insects are important cues for species recognition, gender identification and partner evaluation. In insects, males as well as females can be the signalers and receivers, and the pheromones can be volatile or contact chemical cues, which are integrated to reinforce or refine selection of the right mating partner. Interestingly, sex pheromones and their receptors have evolved independently in insects and vertebrates. Understanding the mechanism and evolution of insect pheromone communication not only contributes to a better knowledge of chemoreception in animals and chemically-driven behaviors, but also provides the basis for insect pest control.