Host-induced ovipositional behavior byLeptinotarsa decemlineata(Say), from Morelos, Mexico, was studied in greenhouse experiments. MorelosL. decemlineatawere unable to oviposit unless fedSolanum angustifoliumMiller, regardless of their larval feeding history. Neither larval nor preovipositional adult feeding on potato,S. tuberosumL., induced oviposition preference for potato. MorelosL. decemlineatahad much lower oviposition preference for potato than Rhode Island beetles, when given potato andS. angustifoliumsimultaneously, and they ceased oviposition immediately after being confined on potato. Encasement of Mexican pupae with Rhode Island pupal exuviae stimulated the emerging adults to oviposit on potato without feeding onS. angustifolium.