Abstract
Male saw-toothed grain beetles (Oryzaephilus surinamensis) and merchant grain beetles (O. mercator) were dissected, and the major differences in their genitalia were reviewed. Differences in the morphology of the internal sac, setae of the lateral lobes, chitinous rods of the median lobe, and setae on the eighth sternite are illustrated with photomicrographs. The only other difference between the 2 species is the outline of the adult head. The dissection procedure is described briefly.