[Objective]To study repellent effect of allicin against armyworm Mythimna separata.[Method]The oral toxicity effect of allicin on Mythimna separata larvae was evaluated and analyzed comprehensively.[Result]Allicin had obvious repellent effect on Mythimna separata.At the same time,since allicin was an unstable volatile substance,it did not have long-term insect repellent effect,and its effective insect repellent time was 20 h and high concentration of allicin was better.[Conclusion]Allicin has a repellent ef...