Abstract: Studies were conducted to evaluate the larvicidal and repellency efficacy of the seed oil of the tallow tree Detarium microcarpum (Guill. and Perr.) (Fam. Leguminosae: Caesalpinioideae) against late instar larvae of the larder beetle Dermestes lardarius Linnaeus, in dried Clarias gariepinus Teugels fish under laboratory conditions. Pure seed oil was applied on the dried fish at concentrations of 0.006-0.025 mL g-1 and a control, with 30 larder beetle larvae each maintained in triplicates for 24-96 h. The 0.006, 0.010, 0.014, 0.022 and 0.025 mL g-1 dosages on treated fish produced 53.33-70, 81.11-92.22, 80-87.78, 82.22-96.67 and 85.56-96.67% mortality of D. lardarius larvae after 24-96 h exposure, respectively. The seed oil also repelled 80-96.67% of the larvae from the treated fish within 24 h. Probit analysis of the bioassay data gave an LC50 value of 0.023 mL g-1 for the seed oil against D. lardarius larvae. The studies demonstrate a very high larvicidal and strong repellency of D. lardarius by D. microcarpum seed oil. These findings indicate a high potential of controlling and protecting dried fish from dermestid beetles infestation using the seed oil.