Pirimiphos-methyl was applied to cleaned hard winter wheat as a water emulsion at gradient doses from 1–10 ppm AI. Then the relative effectiveness of residues in samples withdrawn at intenals during a 12-mo storage period was determined against adults of 4 common species of stored-grain insects. The order of tolerance was: confused flour beetles, Tribolium confusum Jacquelin duVal, > lesser grain borers, Rhyzopertha dominica (F.), > red flour beetles, Tribolium castaneum (Herbst), > rice weevils, Sitophilus oryzae (L.).