Origanum genus belonging to Lamiaceae family has been used extensively throughout the world. Air-dried aerial part of Origanum vulgare L. was subjected to steam distillation to yield the essential oil of which the compounds were elucidated by GC-MS analysis. The main constituents of essential oil were determined as thymol (40.35%), p-cymene (17.32%), γ-terpinene (15.66%), and carvacrol (12.15%). The insecticidal activity of essential oil was executed against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) by fumigation method. It was presented that the essential oil was highly effective against both species. After treatment of essential oil on S. oryzae, 72% and 88% mortality were observed at 48 hours (h) and 72 h respectively. The mortality of R. dominica was determined as 94% and 96% at 48 h and 72 h respectively. Median lethal concentration (LC₅₀) values were found for S. oryzae as 0.086 µL /mL and 0.057 µL /mL at 24 h and 48 h respectively. Moreover, these values (LC₅₀) were presented as 0.11 µL /mL and 0.065 µL /mL at 24 h and 48 h respectively for R. dominica. Hence, the essential oil of O. vulgare could be useful for the managing field populations of S. oryzae and R. dominica.