Cocoa, Theobroma cacao (Linn.) is important as a foreign exchange product. Among the major pests of stored cocoa beans in Western Nigeria, especially in warehouses, is Ephestia cautella (Walker). The effects of ultra violet (254nm) irradiation on eggs hatching, adult emergence and mortality of the tropical warehouse moth E. cautella (Walker) on infested cocoa beans were studied. The eggs, larvae, and adults of the stored product pest Ephestia cautella (Walker) (Lepidoptera; Pyralidae) belonging to 1-3 days old age group were exposed to ultra violet radiation at 254nm wavelength (UV-C) for different duration to determine the irradiation effect on egg hatching, adult emergence from the irradiated larvae and adults mortality respectively. An increase in time of exposure to UV radiation gradually decreased the percentage of eggs that hatched over time; the emergence of adults from irradiated larvae was also reduced as the time of exposure increased. The percentage adult mortality for the exposure periods used (10 and 15 minutes) in relation to control significantly increased as the exposure period increased. In conclusion, it has been found out from this research work that irradiation is a very safe and clean method for food preservation and pest control.