Candidate insecticidal materials were tested on Hard Winter wheat stored in small, intermediate-type bins. A diatomaceous earth dust impregnated with malathion gave the best protection and imparted repellency to the wheat against rice weevils, but addition of the dust reduced the test weight of the wheat. Of the candidate sprays, pirimiphos-methyl and chlorpyrifos-methyl were superior to the standard dose of malathion in protecting the wheat against attack by a number of species of stored-grain insects. Fenitrothion was generally more effective than malathion.