The bacteria, Serratia marcescens (SM1) was previously obtained from the black-winged termite, Odon-totermes formosanus Shiraki. SM1 was highly toxic to O. formosanus, however, the mechanism of toxicity is unclear. In this study, toxicity test results showed that the main com-ponents that affected O. formosanus were in a supernatant and that the insecticidal protease in the supernatant resulted in the death of O. formosanus . In addition, zinc sulphate recovery experiments indicated that the metalloproteinases in the supernatant were more harmful. These results provide a theoretical foundation for the future biological control of termites, the basis for the development of pest control tech-nology and the discovery of new pesticides.