Odontotermes formosanus (Shiraki), a black-winged subterranean termite, is a common forest pest. A red pigment-producing bacterial strain isolated from the termite was identified as Serratia marcescens and named SM1. A bioassay of SM1 on O. formosanus show that the LD 50 ranged from 1.77 × 104 to 10.82 × 104 cells/termite over 21–39 h. Three biological control agents, Beauveria bassi-ana (2 × 1010 cells/mL), Metarhizium anisopliae (1 × 1010 cells/mL) and Bacillus thuringiensis (1.6 × 108 IU/mL), were used for an O. formosanus bioassay. The results show that the insecticidal effect of B. bassiana was stronger than that of M. anisopliae . In addition, two mixtures were obtained by combining B. bassiana (2 × 1010 cells/mL) with SM1 (1.5 × 1010 cells/mL), and M. anisopliae (1 × 1010 cells/mL) with S. marcescens (SM1) (1.5 × 1010 cells/mL) in equal vol-umes. The results show that B. bassiana and SM1 was less effective than SM1 alone. However, the insecticidal effect of M. anisopliae and SM1 was better than that of M. anisopliae or SM1 individually. These studies provide an important contribution for termite biocontrol.