Chrysochus auratus and C. cobaltinus form a hybrid zone in south-central Washington State. Within this hybrid zone, sexual isolation between the two species results in positive assortative mating. Male choice appears to underlie sexual isolation in this system. We investigated the mating cues that males use to identify females as conspecific. Behavioral bioassays using females painted with cuticular extracts revealed that males identify potential mates based on their cuticular compounds. These compounds were shown to be cuticular hydrocarbons through a combination of silica column chromatography and GC-MS. We discuss these results in the context of the selective forces influencing the evolution of reproductive barriers in this hybrid zone.