- Latin synonym: Colias croceus
- Family: Whites and Yellows – Pieridae
- Subfamily: Sulphurs – Coliadinae
- Wing span: Medium-sized, 44–52 mm (1.73–2.08 in.).
- Wing upper side: Reddish yellow, tip and margin black. Middle of forewing with black blotch, middle of hind wing with clear or unclear reddish orange blotch. Occasionally white or yellow individuals.
- Wing underside: Middle of forewing reddish yellow, margin and tip faint olive green. Black blotch in middle. Hind wing faint olive green, middle with 1 or 2 wine-red-edged white blotches. Margins with small darker blotches. Reddish short hairs on wing margins on individuals if not too worn.
- Habitat: Wasteland and fields with pea plants.
- Flying time: Late June–early October (second or later generations wanderers).
- Overwintering form: Caterpillar (rarely observed in Finland).
- Larval foodplant: Pea family (Fabaceae) plants such as medicks (Medicago), clovers (Trifolium) and melilots (Melilotus).
There are three subfamilies of Whites and Yellows in Finland, of which one is the Sulphurs (Coliadinae). Its best known representative is undoubtedly the brimstone. The two other subfamilies are the Whites (Pierinae) and the Mimic sulphurs (Dimorphiinae).
The clouded yellow is not established in Finland, and individuals that are spotted here are wanderers from the south. Like its close relatives, the clouded yellow holds its wings together when it is resting which makes the upper surface difficult to study without catching the butterfly first. Of the same kinds of species, the moorland clouded yellow is more common and the pale clouded yellow less so. The clouded yellow’s more common reddish yellow individuals are easy to spot in the air thanks to the highly eye-catching colour of the upper surface of the wings and the reddish yellow central portion of the forewings. The more rare yellow or white coloured clouded yellows can be most easily differentiated from the moorland clouded yellow by the row of dots along the margin on the underside of their hind wings. From the white pale clouded yellows the rare whitish coloured individuals are more difficult to identify, but good identification markers are clouded yellow’s broader black border area, the larger reddish yellow blotch on the underside of its hind wings, and its greener hue.