Phoxim was tested on hard winter wheat, shelled corn, and sorghum grain as a protectant against adult rice weevils, Sitophilus oryzae (L.); red flour beetles, Tribolium castaneum (Herbst); confused flour beetles, T. confusum Jacquelin duVal; and lesser grain borers, Rhyzopertha Dominica (F.). Evaluations of results were made at intervals by determination of mortalities after aging of the deposits, by counting the number of progeny developing after toxicity test exposures, and by an assessment of progeny damage to the treated grain. Phoxim applied at a rate of 5 ppm was superior to the standard dosage of 10 ppm malathion in all tests. Protection against rice weevil damage was excellent throughout the 12-month storage. A lessening of toxicity effectiveness against the flour beetles and lesser grain borers was noted after 9 months storage, and little progeny damage was inflicted. Definite levels of phoxim residue were evident with the 3 dosages applied. Variations were found, but the recoveries seem representative for 3 scalar rates of application.