The efficacy and persistence of the liquid formulation of spinosad, a commercial bacterial insecticide, against stored-grain insects has been documented through laboratory and field trials. The effectiveness of the dry formulation of spinosad (0.5% purity) against stored-grain insects in unknown. In laboratory tests, adults of the lesser grain borer, red flour beetle, and rice weevil were exposed to untreated hard red winter wheat and hard red winter wheat treated with 1 mg(AI)/kg of spinosad. Adults (25) were added to untreated or spinosad-treated wheat and examined after 7 days to determine mortality and after 49 days to determine adult progeny production. Spinosad was effective in killing lesser grain borers and rice weevils, but not red flour beetles. However, spinosad effectively suppressed progeny of all three species.