The present work aims to evaluate the efficacy of the natural mint oil on
some biochemical constituents of Sitophilus oryzae (l.). Sitophilus granarius (L.) and
Rhizopertha domlnica (F.). The studied characters were adult mortality (%)and the effect of oil on total content of
proteins, lipids, carbohydrates, GOT, GPT and Ach E. Results revealed that insect mortality (%) was increased with increasing
concentration and the exposure period depending on the species. Mint oil was more
toxic to S. granarius (LC5(l = 4.7 mllkg) than S. oryzae (LC5(l = 6.2 mlJlR.
dominica (LC5(l = 10.5 mlfJ(g). Total protein was significantly reduced in the treated insects compared to control. Lipids content was found increased in S. oryzae and S. granarius, while was
found decreased in R. dominica compared to control. Reduction (%) in carbohydrates content was significantly decreased in both
homogenate of S. granarius and R. dominica, while increased in S. oryzae compared
to untreated adults. A significant reduction (%) in GOT, GPT and Ach E. compared to
untreated insects. The present study showed thelt mint oil have direct toxic effects on the
mortality z: studied insects and indirect effects on the studied biochemical constituents         as total proteins, lipids, carbohydrates, GOT, GPT and Ach E.                                . Further studies are required to evaluate effect of this oil on other insects of
stored grains as well as its effect when combined with other control factors.