The present study was carried out to investigate the effect of different doses of gamma irradiation (0, 50,100,500 and 1000 Gy) on the mortality percentage of both of larvae and adult stages of the red flour beetle, Tribolium castaneum Herbst. (Coleoptera- Tenebrionidae). Also, the effect of gamma irradiation on both of the Quinones secretion and the microflora associated with the pest stages was investigated. The results showed that the incremental of adult and larval mortality percentages were significant (P <0.05) affected by an increment of gamma irradiation dose. The results of Gas chromatography-mass spectrometry patterns exhibited a strong inhibitory effect of irradiation on Quinones secreted by both stages. The used doses succeed in reducing the count of microflora were associated with both larval and adult stages. This reduction reached zero for fungi and bacteria isolated from the surface at the dose 1000 Gy. Obtained data suggested that the irradiation of red flour beetles with 1000 Gy is a promising tool for the control of this destructive pest and prevent its harmful effects associated with its infestation.