Abstract: Experiments were conducted to examine the effect of Sudan grass, Sorghum sudanense and vetiver grass, Vetieria zizanioides on the oviposition preference and larval survival of stripped stem borer, Chilo suppressalis in lab, as well as the control effect of the two grasses used as trap crops for suppressing population of C. suppressalis in rice field. The borer female adults preferred to lay eggs on Sudan and vetiver grass in oviposition free selection tests, the number of eggs laid on Sudan and vetiver grass plants were 3.02 and 4.56 times of the number of eggs laid on rice plants, respectively. Both of Sudan and vetiver grass had lethal effect and C. suppressalis larvae could not finish their life cycle as the borer larvae fed on two tested hosts. Field experiment showed in the rice plot surrounded by the two tested hosts had significantly lower dead heart rate than that in rice monocrop plots 20 m away from the treatment block.