Due to its high protein content, cowpea (Vigna unguiculata (L) Walpers) is the most consumed legume crop in tropical and subtropical environments. Callosobruchus maculatus (F) is regarded as a global threat to stored pulses since it attacks several cowpea bean kinds and other stored legumes. Therefore, it is deemed important to develop a safe method to protect cowpea from any infestation. The insecticidal activity of gamma irradiated moringa leaves powder using gamma radiation against C. maculatus adults was examined to protect cowpea seeds from infestation. Also, the current study was carried out to investigate some histochemical aspects of cowpea beetles C. maculatus. Moringa seeds irradiated with 20, 40, 60 and 80Gy obtained results indicating that the adults' mortality was increased and accelerated by using irradiated leaves as compared to the unirradiated leaves. The most effective dose was 40Gy where the percent accumulative mortality was 100% with the lowest median lethal time (LT₅₀) of 54.3 hrs. Moreover, the biochemical studies of adults (control, unirradiated M. oleifera and 40Gy irradiated M. oleifera) revealed a significant rise in both peroxidase and glutathione-s-transferase activities in adults from 40Gy irradiated M. oleifera leaves treatment as compared to the adults from unirradiated M. oleifera leaves treatment and control adults. It could be concluded that leaves powder of irradiated M. oleifera as seed with 40Gy was effective for the control of insect infestation of grains and other stored products; it's also a safer and cheaper control method among integrated pest management program.