Colias croceus
This is a migratory species from southern Europe, with the first wave usually arriving in Sussex in late April and the month of May. They lay their eggs on Lucerne, a variety of clover species, Birdsfoot Trefoil and other native legumes. The offspring generally emerge in mid-August, and these individuals are supplemented by fresh waves of immigration from across The Channel. In some years, there is a further brood in September and October.
In recent years Clouded Yellows have been observed egg-laying at Medley Bottom in October, their larval foodplants Birdsfoot Trefoil and Horseshoe Vetch. At another downland location in East Sussex, very early April Clouded Yellows have been recorded, and these were considered to be over-wintering individuals. With climate change and a succession of mild winters, this species may begin over-wintering on a regular basis.
This is a species that may be very plentiful one year but very scarce, the next. Any downland location may be productive but the area between Birling Gap and Beachy Head is worth a visit, as is Chantry Hill, Mill Hill and Steyning Downland Scheme. Away from downland, Thorney Island is often a good location to see these butterflies. Fresh arrivals may be seen in the spring and in the autumn, they sometimes congregate in large numbers, awaiting favourable weather conditions before departing south across the English Channel. In late autumn, Cissbury Ring and Medley Bottom are favoured locations.
Clouded Yellow nectaring on Verbena Bonariensis – photo by Trevor Rapley
Nectaring on Autumn Hawkbit – photo by Nicholas Turner
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Nectaring on Devilsbit Scabious – photo by Martin Kalaher
Nectaring on Ragwort – photo by Dave Brown
Nectaring on Devilsbit Scabious – photo by Dave Brown
Showing open wings – photo by Dave Brown
Butterfly Conservation Clouded Yellow
