Abstract: This study was initiated in order to determine how long several grain protectants willprovide acceptable protection against the adults and the progeny of Sitophilus oryzae (L.),Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst), when applied to clean easternwhite winter wheat containing 13.6% moisture content. The following insecticides were in theexperiment: mixture of diatomaceous earth (DE) and deltamethrin (DM) (DE/DM insecticide)applied at 100 ppm containing 90ppm of DE and 0.1ppm of deltamethrin active ingredient (a.i.);spinosad technical 92% powder applied at 1ppm a.i.; mixture of chlorpyriphos methyl (CM) anddeltamethrin (DM), formulation Storicide II applied at 3ppm CM and 0.5ppm DM a.i.;pirimiphos methyl, formulation Actellic 5 E applied at 10ppm ai. In the USA, Actellic 5E isprimary registered as a grain protectant on corn and Storicide II on wheat, however, in someEuropean countries, Actellic is registered on wheat, as well. Bioassays were initiatedimmediately after treatment (zero day), 30, 120 and 180 days after the initial treatment and wereconducted under the same conditions. The results demonstrate that, under the grain storageconditions and bioassays implementation, treatment of wheat with 100ppm of DE/DM mixtureand 3ppm of CM and 0.5ppm of DM (Storicide II) provided effective protection against theadults and the progeny of S. oryzae, R. dominica and T. castaneum during the investigatingperiod of 6 months. However, 10ppm of pirimiphos methyl (Actellic 5E) didn’t control the adultsof R. dominica and T. castaneum, and 1ppm of spinosad didn’t control the adults and the progenyof S. oryzae and T. castaneum, immediately after the treatment and 180 days after the graintreatment, as well.