Catocala ultronia

The Dark Red Underwing or Ultronia Underwing (Catocala ultronia) is a moth of the Erebidae family. It is found in most of eastern North America, south to Florida and Texas. It ranges west across the southern parts of Canada to extreme southeast British Columbia.

The wingspan is 46–60 mm. Adults are on wing in August in one generation depending on the location.

The larvae feed on Fraxinus pennsylvanica, Malus species, Populus grandidenta, Prunus pensylvanica, Prunus serotina, Prunus virginiana, and Tilia americana.