Taste plays an essential role in the identification of adequate food sources by insects, including lepidopterans. Characterizing genes that are important to successful transduction of tastants in insects leads to understanding of how tastants can regulate insect behavior. One class of proteins, odorant binding proteins (OBPs), have been shown to play a role in olfactory chemotransduction, but their role in taste transduction has been less clear, especially in immature stages of insects. Taste has been shown to be central in host preference by the larva of the tobacco hornworm, Manduca sexta (L.) (Lepidoptera: Sphingidae), and its preferred host plants in the family Solanaceae. We report the discovery of a new OBP gene, Mad10, expressed in the gustatory sensilla styloconica of M. sexta larvae. This is the first time that the expression of an OBP is found in the sensilla styloconica of any lepidopteran.