The Locust Underwing (Euparthenos nubilis) is a species of moth in the Erebidae family and the only member of its genus Euparthenos. The adults resemble some of the underwing moths of genus Catocala, which are fairly close relatives, in color, pattern, and the habit of resting on tree trunks. But E. nubilis can usually be immediately recognized by the 4 concentric black bands per hindwing, as opposed to one or two (at most 3) in Catocala. Color morphs of E. nubilis with altered pattern are known, however, and these may be hard to recognize without detailed examination.