The screening for insecticidal principles from several Chinese medicinal herbs showed that the ethanol extract of Aconitum episcopale roots possessed significant feeding deterrence against the red flour beetle, Tribolium castaneum . From the ethanol extract, six feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as chasmanine, crassicauline A, karacoline, sachaconitine, talatisamine, and yunaconitine from their spectroscopic data. Chasmanine, talatisamine, karacoline, and sachaconitine exhibited feeding deterrent activity against T. castaneum adults, with EC(50) values of 297.0, 342.8, 395.3, and 427.8 ppm, respectively. Yunaconitine and crassicauline A also possessed feeding deterrent activity against T. castaneum adults, with EC(50) values of 653.4 and 1134.5 ppm, respectively.