This study scientifically examined the residual effect of fruiting body of oystermushroom, Pleuotus ostreatus, against adult red flour beetle Tribolium castaneum (Herbst) at different time intervals. In residual film toxicity, hot water and methanol-chloroformextracts of oystermushroomand petroleum ether and residual fractions of methanol-chloroform extract showed moderate activity against Tribolium castaneum. Residual fraction showed the lowestLD 50 values (0.206mg/cm2) indicating its potent efficacy against Tribolium castaneum. The order of toxicity on Tribolium castaneum was residual fraction>petroleum ether fraction>methanol-chloroform extract>hot water. In addition, the results of this study also indicate that, the toxicity for each test sample against Tribolium castaneum was increased with increasing of time of exposure.