The Clouded Yellow is a medium-sized golden-yellow butterfly. It is a migrant species which flies here from North Africa and southern Europe. Clouded Yellows are fairly rare in most years but occasionally turn up in enormous numbers - long remembered as 'Clouded Yellow Years'. Adults may arrive at any time during the spring and summer, when they can be found in grassy places, particularly near the south coast. Foodplants of the caterpillars include wild and cultivated clovers and Common Bird's-foot Trefoil.
How to identify
The Clouded Yellow has bright yellow to vivid orange upper wing surfaces, lined with broad, black edges, and a yellowy-green underside.
Where to find it
Can turn up anywhere, but most frequent in southern areas.
When to find it
How can people help
In southern England, Clouded Yellows prefer chalk downland habitats - patchworks of chalk grassland, heath, scrub and ponds found on chalk hills. Areas of rare and unique wildlife, chalk grasslands, in particular, have been likened to rainforest for the diversity of species they hold. But they are being lost at an alarming rate due to changes in land use causing the decline of grazing: it's estimated that we've lost 80% of our chalk grassland over the last 60 years. The Wildlife Trusts manage many grassland and downland nature reserves for the benefit of the rare wildlife they hold. You can help too: volunteer for your local Wildlife Trust and you could be involved in everything from scrub-cutting to stockwatching.