The efficacy of bifenthrin (0.5 mg/kg) piperonyl butoxide (7 mg/kg) chlorpyrifos-methyl (10 mg/kg) against beetle and psocid pests of sorghum was evaluated in silo-scale trials in southeast Queensland, Australia. The pyrethroid bifenthrin was evaluated as a potential new protectant in combination with the organophosphate chlorpyrifos-methyl, which is already registered for control of several insect pests of stored cereals. Sorghum (≈200 metric tons) was treated after both the 1999 and 2000 harvests and sampled at intervals to assess treatment efficacy and residue decline during up to 7 mo of storage. Generally, test strains of the beetles Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L), and Cryptolestes ferrugineus (Stephens) were prevented from producing live progeny for up to 7 mo. The treatment failed against one strain of R. dominica known to be resistant to bioresmethrin and organophosphates. Two malathion-resistant strains of O. surinamensis were marginally controlled with 94–100% fewer adult progeny produced. For psocids, no strains of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), or Liposcelis paeta Pearman produced live progeny, although the control of a field strain of Liposcelis entomophila (Enderlein) was generally poor. Results show that this treatment should protect sorghum for at least 7 mo against most prevalent strains of grain insect in eastern Australia, although control may be limited in areas in which L. entomophila or pyrethroid-resistant R. dominica are present.