Abstract: The larva of Microelalopha trogloyta exists in endogenous enzymes of protective system such as POD,CAT and SOD. The larva of M. trogloyta was treated with 1% aloperinc. The activities of POD and CAT were lower than that of CK at the early stage,while the activities of POD in the larvas of M. trogloyta were much higher than that of CK after 10～46 h,The CAT activity was the same as POD, but after 27～45 h. The activity of SOD was much higher than that of CK from 1 to 27 h. The results showed that the aloperine was poisonous to the larva of M. trogloyta.