Laboratory experiments were conducted to assess the insecticidal effects of seed powders of Dennettia tripetala (Pepper fruit) and Piper guineense (Black papper) on the egg, larva, and pupa of Callosobruchus maculatus. Results indicated that each of these peppers was effective in the control of C. maculatus at the egg stage. Virtually no emergence occurred when treatment of both peppers was applied within the first three days of oviposition. Beyond this period, significant emergence occurred. Results also indicated that these peppers were not effective during the larval and pupal stages. This is attributable to the fact that the larva and pupa develop within a single seed and are thus, shielded from the effects of these peppers. In contrast, the eggs are attached singly to the seeds. This study has, therefore, revealed that for the effective control of this pest, it is critical to apply these peppers before egg hatch; once the egg hatches and the larva bores into the seed, control is uncertain.