Clouded Yellow Butterfly (Colias croceus) - Brighton, September 2025

I'd not seen this butterfly in the UK for around three years, so I was quite excited when I spotted a lone individual in a local field in early September. I spent the next 90 minutes or so, chasing this poor butterfly up and down a long, steep pathway at least five times, trying and failing to get a photo or two. I pretty much thought my chance had gone for another year until in the same field three weeks later, this far more cooperative individual appeared almost at my feet. The Clouded Yellow is a strongly migrant butterfly with breeding grounds in both southern Europe and North Africa. From there it spreads throughout Europe extending to the southern half of the UK. Colias croceus can also be found across vast swathes of Asia. A common sight throughout most of Europe, numbers visiting the UK fluctuate greatly from year to year, with numbers on a strong upwards trajectory. In recent years there have even been reports of sightings in the UK before evidence of that year’s inward migration. This suggests a low level of winter survival, either as chrysalises or larvae? This is a medium-sized butterfly with wings measuring up to 62mm on females and 58mm on males. The upper sides (rarely seen as the butterfly nearly always settle with its wings closed) are a golden-yellow to orange-yellow with broad black/brown borders, within which females display rows of yellow/cream spots. Both sexes sport a slightly off-centre dark spot on the forewings. The underside are a light yellow/green colour with a central, bordered white spot on the hind wings. The first of the year’s migrants generally appear in the UK in May with numbers peaking in late August and early September. Depending on environmental conditions, up to three generations might be produced between May and late summer/early autumn. While Colias croceus can turn up almost anywhere, it tends to frequent open, sunny habitats with plenty of nectar sources, particularly grasslands and coastal areas. As I found in 90 minutes of fruitless stalking, in flight they are fast and direct and even when they finally stop at a food plant, they generally don’t linger for more than 4 or 5 seconds at each plant. Having said that, the individual in this video lingered far longer which enabled this video and some decent photos. Food plants include Dandelion, Fleabane, Knapweeds, Ragwort and Thistles. Eggs are laid singly, several hundred at a time, on the leaves of plants like Clover and Bird's-foot trefoil. Depending on environmental conditions, the newly hatched plain green caterpillars feed for between 3 and 6 weeks before pupating on the stem of a food plant, emerging as an adult between two and three weeks later. Two very similar Colias species, Berger's Clouded Yellow (Colias alfacariensis) and the Pale Clouded Yellow (Colias hyale) can also be found in the UK, but are much rarer visitors. Nevertheless, it’s always worth taking care with your ID, because they can be tricky to separate. *** One of over 600 wildlife videos on this Channel, if you've enjoyed what you've just seen and read, please feel free to comment, 'like' and subscribe. PK