Potanthus omaha has a wide head, large eyes and a thick body. The upper sides of the wings are dark brown with bright yellow-orange markings, the veins are noticeably blackened on the yellow band. The undersides of the wings are black with the same markings as the upper wings, but the costal half of the forewings and hindwings are covered with yellowish scales.
Larva: Potanthus omaha larva has a pale green translucent body with a dark green dorsal line, its head is dark brown.
Pupa: Potanthus omaha pupae are white and shiny with yellowish thorax.