Catocala relicta, the white underwing or relict, is a moth of the family Erebidae. The species was first described by Francis Walker in 1858. It lives in southern Canada, from Newfoundland to Vancouver Island, south to Missouri, and Arizona.

The wingspan is 67–75 mm. Adults are on wing from July to September in one generation depending on the location.

The larvae feed on Betula papyrifera, Carya ovata, Populus alba, Populus balsamifera, Populus deltoides, Populus nigra, Populus tremuloides, Quercus species, and Salix species (including Salix eriocephala).

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