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A small (1.8-2.0 cm wingspan) day-flying moth with black and white wings. The black forewings are crossed by a basal line of scattered white scales, a more prominent white antemedian band and a prominent white postmedian band divided by a series of small black dots and bent sharply outward near the midpoint. The subterminal area is black and is crossed by a subterminal line consisting of a series of small white crescents. Essentially the same pattern occurs on the hindwings. The fringe is black checkered with white at the veins. Very similar to forms of both Rheumaptera hastata and Rheumaptera subhastata, both of which are larger and usually have more extensive areas of black or white. E. alternata is also larger and is mostly grey, not black, and lacks the crisp, busy pattern of sperryi.

Until described as a separate species by Herbulot in 1951, sperryi was thought to be conspecific with Palaearctic E. tristata (L.) and was listed by both Bowman and Jones as E. tristata. There are several closely related and almost identical looking species in the Palaearctic. The specimen illustrated above is from Dry Island P. Pk., AB.