Contact toxicities of Acorus calamus L. (Arales: Araceae) extracts obtained from four published extraction methods: soakage, soxhlet, ultrasonic and supercritical fluid CO₂ (SFE-CO₂), were compared in this study. Under the given extraction conditions, SFE-CO₂ extract exhibited the highest contact toxicity against S. zeamais of the four methods. With the SFE-CO₂ method, extraction temperature, pressure, time and the amount of EtOH (the extraction solvent) were identified as having a significant effect on the extract. Orthogonal experiments showed that the optimal extraction parameters were: temperature--55°C, pressure--35 MPa, time--40 min and EtOH--150 mL per 200 g of dry powder. Under these conditions, the yield was 4.12% and the LD₅₀ of the extract against S. zeamais after 96 h of treatment was 27.26 µg cm⁻². β-asarone was the dominant component of the extract derived from the SFE-CO₂ method, accounting for 24.39% of the extract. These results may contribute to the designing of large-scale production processes for obtaining A. calamus extract, which proves to be an effective alternative for the control of stored product insect pests.