The Clouded Yellow (Colias croceus) is one of the most-widespread species in Europe and can be seen throughout the spring and summer in Corfu. In flight they are easily identified by the intense yellow and black colouring. Like all species of Colias, the only way to see their open wings is in flight, they never open their wings at rest. A small number of females display an almost white appearance which can make them look like a different species and are known as the Helice Form.