The potential of using synthetic herbivore-induced plant volatiles to enhance conservation biological control of insects and mites in hops and grapes is being researched in Washington State. Results to date indicate that a number of important natural enemies in these crop ecosystems are attracted to sticky traps baited with methyl salicylate (MeSA), hexenyl acetate, farnesene and octyl aldehyde. Further, hop yards and grape blocks baited with slow release dispensers of MeSA appear to recruit larger populations of certain beneficial insects than unbaited areas, resulting in some instances, in improved biological control of spider mites. The use of synthetic plant signaling compounds as 'Herbivore-Induced Plant Protection Odors' (HIPPOs) may provide a novel yet practical option for improving the efficacy and reliability of conservation biological control in a variety of agricultural ecosystems.