(R)-Terpinen-4-ol was mixed in an artificial diet at a concentration of 1 mg/g of diet, and the diet was fed to the last instar larvae of common cutworm (Spodoptera litura). Metabolites were recovered from frass and analyzed spectroscopically. (R)-Terpinen-4-ol was transformed mainly to (R)-p-menth-1-en-4,7-diol. Similarly, (S)-terpinen-4-ol was transformed mainly to (S)-p-menth-1-en-4,7-diol. The C-7 position (allylic methyl group) of (R)- and (S)-terpinen-4-ol was preferentially oxidized.