The screening for insecticidal principles from several Chinese medicinal herbs showed that the stem bark of Erythrina variegata var. orientalis possessed significant feeding deterrence against maize weevils, Sitophilus zeamais. Bioassay-directed fractionation of the stem bark extract of E. variegata var. orientalis resulted in the isolation of two alkaloids, identified as erysopine and erysovine from their spectroscopic data. Erysopine and erysovine possessed antifeedant activity against S. zeamais adults with EC50 values of 108.5 and 89.7 ppm, respectively.