Three species of flat grain beetles (Cryptolestes spp.) occur in stored grain in Australia. Adults are fast moving, small (2mm), flat, with longer antennae than most stored grain pests. Cryptolestes species occur in all grain growing regions of Australia. One species, the rusty grain beetle, Cryptolestes ferrugineus, has developed a strong resistance to phosphine at a number of sites in eastern Australia. Correct identification of this pest will facilitate appropriate management practices. Following is a guide to the identification of flat grain beetle species in Australia.