The insecticidal activity of Acorus calamus L.rhizome-derived material against adults of Sitophilus zeamais Motschulsky was examined by using repellency method and contact toxicity.The biologically active constituent of the A.calamus rhizome was separated and identified.The results showed that the ethanol extract of A.calamus had strong repellency and contact effect to S.zeamais and the active constituent of the A.calamus was characterized as (Z)-asarone by spectroscopic analysis.Responses from the tests varied with exposure times and doses.In the repellency test,ethanol extract of A.calamus had 93.92% repellency at 629.08μg/cm2 but only 71.38% at 157.27 μg/cm2 12 h after treatment.As a contrast,(Z)-asarone showed 84.50% repellency at 314.54 μg/cm2 and 77.02% at 78.63μg/cm2 12 h after treatment.In the filter paper diffusion test,ethanol extract of A.calamus caused 95.56% and 17.78% mortality to S.zeamais at 314.54μg/cm2 and 78.63μg/cm2 4 days after treatment,while (Z)-asarone brought about 100.00% and 15.56% mortality at 40.89 μg/cmz and 15.73μg/cm2 respectively.These results indicate that the insecticidal activity of the A.calamus extract may be due to (Z)-asarone.