Nyceryx stuarti is a moth of the Sphingidae family. It is found from Costa Rica and Peru to Brazil, Bolivia and Paraguay.The wingspan is about 66 mm. It is similar to Nyceryx riscus, but larger and darker and the forewing apex is distinctly truncate.Adults are probably on wing year round.The larvae probably feed on Pentagonia donnell-smithii and Chimarrhis parviflora.