The feeding deterrent activity of alkyl-substituted γ- and δ-lactones, including a group of lactones obtained from linalool against peach potato aphid (Myzus persicae [Sulz.]) and Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say), was investigated. the deterrent activity was species-specific and developmental-stage-specific (CPB). The strongest antifeedants for L. decemlineata larvae and adults were linalool-derived unsaturated lactones (Z) 5-(1.5-Dimethyl-hex-4-enyldiene)-dihydro-furan-2-one and (E) 5-(1.5-Dimethyl-hex-4-enyldiene)-dihydro-furan-2-one, and for CPB larvae – saturated lactone with three alkyl substituents, the 4-Isobutyl-5-isopropyl-5-methyl-dihydro-furan-2-one. The settling of M. persicae on plants was strongly deterred by iodolactones: 5-(1-Iodo-ethyl)-4.4-dimethyl-dihydro-furan-2-one, 5Iodo-4.4.6-trimethyl-tetrahydro-pyran-2-one, 5-Iodomethyl-4-isobutyl-5-isopropyl-dihydro-furan-2-one, and the saturated lactones: 4.4.6-Trimethyl-tetrahydro-pyran-2-one and 4-Isobutyl-5-isopropyl-5-methyl-dihydro-furan-2-one. None of the tested lactones deterred aphid probing, but the probes were significantly shorter as compared to the control. The reduction in probing time may decrease the ability to transmit virus diseases by aphids.