Oxylipins, lipid-derived signaling molecules have important functions in plant development, reproduc-tion and responses to external stimuli. Jasmonates (JAs), C 6 -aldehydes, and their corresponding deriv-atives, produced by the two main competing branches of the oxylipin pathway, the allene oxide syn-thase (AOS) and hydroperoxide lyase (HPL) branches, respectively. These two branches share a sub-stantial overlap in their regulatory functions. Majority of experiments to define the role of C 6 -aldehydes in plant defense responses were restricted to external application of aldehydes or the use of genetic manipulation of HPL expression levels in plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C 6 -aldehydes and jasmonates in me-diating direct and indirect plant-defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae) and the volatiles emitted by these plants upon aphid infestation or me-chanical wounding were characterized. These experiments led to identification of hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani), a natural enemy of aphids.