Control of stored-product insects with pirimiphosmethyl applied at rates of 5, 10 or 15 ppm to rough rice was compared directly with the control obtained with 14 ppm malathion when the treated rice was stored in fiberboard drums and subjected to constant, heavy infestation pressure for 12 months. Malathion was ineffective in protecting the grain from a malathionrestant strain of the Angoumois grain moth, Sitotroga ceralella (Olivier). Pirimiphos-methyl at 10 and 15 ppm protected the rice from all insect infestation for 12 months. Chemical residues in the rought rice and in all milling fraction were determined.