In this work, we have investigated chemical composition and insecticidal effectiveness of Mentha pulegium and Thymus capitatus areal parts essential oil from Tunisia against the major stored grain pest: Tribolium castaneum. There are qualitative and quantitative differences in the chemical compositions of the two studied oils. GC/MS analysis showed that Pulegone (39.1541), Menthone (35.6612%), Piperitenone (3.9858%); piperitone (3.5599%) and Isopulegone were the major compounds of Mentha pulegium essential oil. Whereas, Thymus capitatus essential oil was characterized by Thymol (76.50%), Carvacrol (3.18 %), p-cymene (3.1788%) and β- caryophyllene (2.786%) as major compounds. Results revealed that both studied oils exhibited fumigant toxicity potential. The fumigant tests showed that Mentha pulegium essential oil was more toxic than Thymus capitatus essential oil toward Tribolium castaneum. The corresponding LC50 and LC95 values were respectively 33.740- 159.06 μL/L air for Mentha pulegium and 377.34-1009.83 μL/L air for Thymus capitatus. Results of this study support the use of Mentha pulegium and Thymus capitatus essential oils as fumigant bioinsecticide against stored product pests of economic importance.