Oils from the seeds of neem, Azadirachta indica A. Juss and from a brown pepper, Piper guineense Schum and Thonn afforded protection to cowpea seeds from Callosobruchus maculatus infestation beyond 3 months. Insecticida! efficacy was higher with Piper seed oil (PSO). At 24 hr after surface treating cowpea seeds with 2 and 3 ml/kg of PSO, bruchid mortality reached 100 %, but with neem seed oil (NSO), mortality was 65–100% at 3–5 days. Oviposition in control averaged 60.75 eggs, 49.5 eggs in NSO and 15.5 with PSO. Reproductive efficiency (RE) of PSO-treated females was nil, and very low (1.7 to 2%) with neem oil, but high in control confirming adverse ovicidal effects of both oils. Piper oil prevented emergence of F1 bruchids and neem oil prolonged their mean development period over the control. Neem oil reduced seed damage by 94.67%. Because Piper seeds are a condiment in some Nigerian dishes, and are also used therapeutically in many traditional diseases, there may be no toxicity. However, yield of PSO is much less than that of neem from an equal weight of seeds extracted with organic solvents.