Description: Wingspan 52-62mm. In the male the uppersides are bright orange-yellow with a broad black border to both wings. There is a bright orange spot on the hindwings and a black spot in the forewing. The underside of the forewings are pale yellow with small black spots. The hindwing undersides are green with a central silver spot outlined in red. The antennae are reddish. Females, which come in two forms, are larger and paler than males and the black borders contain yellow or creamy white spots. The normal female form has a pale yellow ground colour. In the form helice the ground colour is creamy white. Approximately 5-15% of females are of this form. Adults have been seen in all months between mid May and mid November, with the majority in August and September.

World Distribution: North Africa, southern Europe, Asia Minor, Arabia east to Iran. Migrants can reach as far north as 62°N.

Irish Distribution: The Clouded Yellow is a migrant butterfly which arrives each year from southern Europe to Britain and Ireland. In N. Ireland it is sporadic in occurrence. Up to the mid 1980s adults were seen on average once every 8 years, but since 1990 it has become almost annual. Large numbers were seen in 1998 and 2000, but none were reported in 2001. The species has been seen in all counties, though like all migrant species, it is most commonly seen in the south and east especially on the coast of Down.

Ecology: The Clouded Yellow has permanent populations in southern Europe and North Africa. There is an annual northward movement which varies in strength. Arrivals in N. Ireland are most frequent in late summer, but arrivals in May and June are not unknown. These early arrivals can produce a locally bred brood which can be seen from July onwards. Like all migrants adults can turn up anywhere, but are most often seen in open sunny grassland. The larval foodplants are species of clover. Adults feed on the nectar of clovers and a wide variety of other plants.

Key Identification Features:

• Most individuals have orange-yellow ground colour
• All forms have broad black borders to fore and hindwings
• Female form helice has yellow replaced by creamy white

Distribution Map from NBN: Colias croceus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Colias croceus at iNaturalist World Species Observations database.