The generic name of the light crimson underwing, Catocala derives from the Greek 'kato' meaning below and 'kalos' meaning beautiful, and refers to the brightly coloured hindwings of the underwing moths. This species is similar in appearance to the dark crimson underwing Catocala sponsa; the hind wings of both are crimson and black in colour. The caterpillar is greenish-grey and has yellow-brown patches.