Herpetogramma sphingealis sp. n., a new species of Crambidae (Lepidoptera), is described from Québec, Canada. The species is included in the genus Herpetogramma Led., 1863, a genus in the subfamily Spilomelinae. Adults and genitalia of this species are described and illustrated, as well as those of H. aeglealis (Walker, 1859) and H. thestealis (Walker, 1859), and adults of the semi-melanic form of H. aeglealis are illustrated.