The Clouded Yellow is one of the truly migratory European butterflies and a regular visitor to Britain and Ireland. Although some of these golden-yellow butterflies are seen every year, the species is famous for occasional mass immigrations and subsequent breeding, which are fondly and long remembered as ''Clouded Yellow Years''. A small proportion of females are pale yellow (form helice), which can be confused with the rarer Pale and Berger's Clouded Yellows.
Size and Family
- Family: Whites and yellows
- Size: Large
- Wing Span Range (male to female): 57-62mm
A range of leguminous plants is used, including wild and cultivated clovers (Trifolium spp.), Lucerne (Medicago sativa), and less frequently, Common Bird's-foot-trefoil (Lotus corniculatus).
Clouded Yellows may be seen in any habitat, but congregate in flowery places where the larval foodplants grow. As clovers are still commonly cultivated, the Clouded Yellow is one of the few butterfly species that have no difficulty locating breeding habitat in the modern farmed countryside. In southern England, there is a preference for unimproved chalk downland.