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Investigations have indicated that storage pests pose a great threat to global food security by damaging food crops and other food products derived from plants. Essential oils are proven to have significant effects on a large number of stored grain insects. This study evaluated the contact toxicity and fumigant activity of the essential oil extract from the aerial parts of <i>Elsholtzia ciliata</i> and its two major biochemical components against adults and larvae of the food storage pest beetle <i>Tribolium castaneum</i>. Gas chromatography&#8722;mass spectrometry analysis revealed 16 different components derived from the essential oil of <i>E. ciliata</i>, which included carvone (31.63%), limonene (22.05%), and <i>&#945;</i>-caryophyllene (15.47%). Contact toxicity assay showed that the essential oil extract exhibited a microgram-level of killing activity against <i>T. castaneum</i> adults (lethal dose 50 (LD₅₀) = 7.79 &#956;g/adult) and larvae (LD₅₀ = 24.87 &#956;g/larva). Fumigant toxicity assay showed LD₅₀ of 11.61 mg/L air for adults and 8.73 mg/L air for larvae. Carvone and limonene also exhibited various levels of bioactivity. A binary mixture (2:6) of carvone and limonene displayed obvious contact toxicity against <i>T. castaneum</i> adults (LD₅₀ = 10.84 &#956;g/adult) and larvae (LD₅₀ = 30.62 &#956;g/larva). Furthermore, carvone and limonene exhibited synergistic fumigant activity against <i>T. castaneum</i> larvae at a 1:7 ratio. Altogether, our results suggest that <i>E. ciliata</i> essential oil and its two monomers have a potential application value to eliminate <i>T. castaneum</i>.