The sex pheromone of Cochylis arthuri Dang was identified as a 80:20 mixture of (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (E)-11-tetradecenyl acetate (E11-14:OAc). Cochylis arthuri is a congener of the banded sunflower moth, Cochylis hospes Walsingham, which is a major pest of sunflower, Helianthus spp. (Compositae), in the Great Plains region of North America. Both are found sympatrically on sunflower in this region, although C. arthuri appears to be less common. Field testing of various blends, in sticky traps, showed that a loading of 80 µg Z11-14:OAc and 20 µg E11-14:OAc on a red rubber septum gave the best catches. In field trials in sunflower plots, traps baited with either the C. hospes blend or the best blend tested for C. arthuri only caught significant numbers, relative to blank traps, of males of the respective species, suggesting that the sex pheromones of the two species are specific under those conditions. The identification of an attractive blend of the sex pheromone of C. arthuri will give researchers another tool to investigate the pest status of C. arthuri on sunflowers.