The Clouded Yellow is a strong migrant, and most years it reaches southern England, occasionally travelling into Wales, Ireland, northern England and southern Scotland. Some years these colourful butterflies are abundant in southern Britain and in other years only a few make it this far north. The origin of these migrants is northern Africa and southern Europe, where they are both widespread and abundant except at very high altitudes.
In the pictures above, male and female are yellow. There is also a form Colias croceus helice (commonly referred to as form helice) wherein the female is creamy white rather than yellow.
The wingspan of a female is 4.6 to 6cm, with males somewhat smaller at 4.6 to 5.4cm.
Widely distributed in southern Europe and northern Africa, the range of the Clouded Yellow extends right across the Middle East and into Asia.
The main larval foodplants of the Clouded Yellow are clovers and related species such as the various medicks, Lucerne and occasionally Common Bird's-foot-trefoil. The pale green caterpillar is covered with short pale hairs. It has whitish lines along the sides of its body and an orange-yellow stripe through the centre with small black spots beneath the stripe.