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There are four major insect pests attacking achenes of sunflower in the Great Plains of North America (Charlet et al., 1987); the red sunflower seed weevil, Smicronyx fulvus LeConte (Coleoptera: Curculionidae), the gray sunflower seed weevil, S. sordidus LeConte (Coleoptera: Curculionidae), the banded sunflower moth, Cochylis hospes (Walsingham) (Lepidoptera: Cochylidae), and the sunflower moth, Homoeosoma electellum (Hulst) (Lepidoptera: Pyralidae). Identification of achenes damaged by larvae of these species is important for assessment of yield loss caused by each species (Peng and Brewer, 1995). Achenes infested by the gray sunflower seed weevil are easily identified because they are enlarged and protrude above the surrounding achenes on intact sunflower heads and the kernel is entirely consumed (Brewer, 1991). Descriptions of achenes infested by larvae of the other three species are similar (Carlson, 1967; Oseto and Braness, 1979; McBride and Charlet, 1991) except for the location of feeding/exit holes on the surface of the achenes infested by the red sunflower seed weevil and banded sunflower moth (Charlet and Gross, 1990). The red sunflower seed weevil oviposits in the developing achenes. The larvae feed on the developing kernels and when mature chew emergence holes in the pericarp (hull) (Oseto and Braness, 1979). The banded sunflower moth and sunflower moth oviposit on the bracts and florets. Early instars feed on the pollen and florets, later instars penetrate into achenes and feed on the developing kernels (Charlet et al., 1987, Charlet and Gross, 1990). In this study, we describe achenes infested by the red sunflower seed weevil, banded sunflower moth and sunflower moth and provide characters for separation of achenes infested by each of these pest species.