Semiochemicals are an important alternative to chemical insecticides in crop production. In this chapter, we summarize current applications and future avenues of research-driven developments of plant protection against insect pests involving semiochemicals. In the past, mainly pheromones have been used in different ways, such as insect population monitoring, mass trapping and mating disruption techniques. Companion plants and plant-derived volatiles are currently used in push-pull strategies, and the choice of resistant cultivars can help reduce insect pests. Research is now focusing efforts on developing future strategies to enhance plant defences against insects using artificial induction of volatile emission with defence stimulators or profiting from plant-plant communication with volatiles. Additionally, volatiles produced by substrate-related microorganisms affecting pest insect behaviour provide the basis for new developments in plant protection. Finally, profound knowledge on molecular mechanisms of odour perception is a starting point for “reverse” chemical ecology. High-throughput ligand identification of odorant receptor proteins with electrophysiological and modelling approaches can accelerate the identification of new insect repellents and attractants. In spite of the strong potential of using semiochemicals in plant protection, plasticity of the insect olfactory system and the potential development of resistance to the employed treatments need to be anticipated.