Tetradenia riparia(Hochst.) Codd. is a Rwandan traditional medicinal plant reported to be used to prevent postharvest insect damage in traditional storage. Addition of milled or crushed leaves ofT. ripariaat ≥4% (wt/wt) significantly decreased fecundity and fertility ofZabrotes subfasciatus(Boheman) andAcanthoscelides obtectus(Say), which resulted in smaller F1 populations. A concentration of 10% leaves (wt/wt) also increased cumulative larval and pupal mortality forZ. subfasciatus. The increased mortality may be caused by increased competition betweenZ. subfasciatuslarvae within the bean. Competition could be influenced by the great decrease in percentage of beans oviposited upon byZ. subfasciatus.The control achieved against the F1populations did not persist. Hormoligosis, in the form of increased fecundity, was also found for leaves from one supply at the 1% concentration. In general, the initial inhibitory effects were found to be reproducible using different supplies of leaves. Results were also quite consistent for the two species of Bruchidae, despite innate behavioral differences between them at oviposition and hatch.