Insecticidal activities of two powdered spices, black pepper and red pepper on adults of Rhyzopertha dominica (F.) and Sitophilus granaries (L.)Abstract : The experiment was conducted to investigate the insecticidal potency of black pepper (Piper nigrum L.) seed powder and red pepper (Capsicum annuum L.) fruit powder, against two important stored-product pests. These powders were mixed with 20 g wheat grains as direct admixtures at five different rates viz, 0, 0.15, 0.2, 0.27, 0.37 and 0.5% (w/w) for black pepper and 0, 0.5, 0.85, 1.5, 3 and 5% (w/w) for red pepper to assess for mortality and reduction of Fl progeny. The treated grains were infested with 20 adults. All insects were removed after 14 days and the experiments were monitored for the extra 36 days in order to count the number of emerged adults. The results revealed that black pepper at 0.5% concentration caused 100% mortality of S. granarius in the first five days, also R. dominica showed complete mortality at 5% level after 14 days, but red pepper did not cause complete mortality on two insects after 14 days. Both plant materials caused complete reduction in Fl progeny of S. granarius at highest tested dosages. Also they significantly reduced F1 progeny emergence of R. dominica. This plant powders exhibited promising potential in protecting wheat grains against two species of insects.