[Aim]  To screen essential oils for insecticidal activity against Sitophilus zeamais and Rhyzopertha dominica . [Methods]  Essential oils were extracted by the steam distillation method, and their fumigant and contact toxicities evaluated using the filter paper fumigation, and topical application, methods, respectively. The chemical composition of essential oils was analyzed using gas chromatography-mass spectrometry (GC-MS). [Results]  Eucalyptus camphora had the highest fumigant toxicity against S. zeamais after 24 h, with an LC₅₀ of 15.49 mg/L. E. robusta essential oil had the strongest fumigant activity against S. zeamais after 48 h, with an LC₅₀ of 9.45 mg/L. E. triflora essential oil had the highest fumigant toxicity against R. dominica at both 24 and 48 h, with LC₅₀ values of 21.86 and 17.30 mg/L, respectively. E. trifloral essential oil had the strongest contact toxicity against both S. zeamais and R. dominica , with LD₅₀ values of 33.33 and 6.60 μg/adult after 24 h, and 29.67 and 4.13μg/adult after 48 h, respectively. GC-MS analysis revealed that the major components of E. camphora essential oil were eucalyptol (52.17%), (+)-α-pinene (9.15%), and α-terpineol (8.50%). E. robusta essential oil of was mainly comprised of α-pinene (39.91%), α-phellandrene (9.69%), (R)-(+)-limonene (7.68%), β-pinene (6.94%) and 4-isopropyltoluene (5.84%). The principal constituents of E. triflora essential oil were α-pinene (18.31%), eucalyptol (9.26%), 4-isopropyltoluene (8.85%) and α-terpineol (5.39%). Among the individual compounds, 4-carvomenthenol from E. robusta essential oil had the highest fumigant toxicity against S. zeamais, with LC₅₀ values of 58.65 and 47.37 mg/L at 24 and 48 h, respectively. In E. triflora essential oil, α-terpineol had the highest fumigant toxicity against R. dominica, with LC₅₀ values of 32.87 and 33.03 mg/L at 24 and 48 h, respectively. Moreover, α-terpineol in E. triflora essential oil had the highest contact toxicity against S. zeamais, with LD₅₀ values of 153.97 and 94.06 μg/adult after 24 and 48 h, respectively. In addition, α-phellandrene in E. triflora essential oil had the highest contact toxicity against R. dominica, with LD₅₀ values of 192.61 and 62.70 μg/adult after 24 and 48 h, respectively. [Conclusion]  These findings suggest that Eucalyptus essential oils and their bioactive components have potential as environmentally friendly grain storage pest control agents. Plant-derived insecticides from Eucalyptus species have promising potential for sustainable pest management applications.