The present investigation was undertaken to study the effectiveness of Olea europaea leaves extract and gamma irradiation against the greater wax moth, Galleria mellonella larvae. Acetone Olea europaea leaves extract was prepared at (2, 1, 0.5, 0.25and 0.125%) to be examined for their efficacy against the 4th instar larvae. The effects of 5 different doses of gamma irradiation (50, 100, 150, 200 and 250 GY) was also assayed on the biology of greater wax moth, G. mellonella. Results revealed that larval mortality of G. mellonella reached (8.2%) and (57.3%) after1&10 days from treatment, with the lowest concentration of 0.125%. While, the highest concentration 2 % caused (31.0%) and (100 %) larval mortality after1&10 days post-treatment for plant extract. All doses of gamma irradiation prolonged the larval period and reduced both pupation and percentage of adult emergence. The number of eggs laid was decreased by increasing the irradiation doses at all treatments. The insects failed to lay any eggs especially, in the treatments (treated male × treated female) and (normal male × treated female) with doses 200 and 250 GY, respectively