It’s fair to say that 2026 has been (and still is) a good year for Clouded Yellows, as the graph below (taken from iRecord) shows:

They are a migrant species that also breeds here. The ones we are seeing now in such extraordinary numbers are, in all probability, a mixture of recent immigrants from continental Europe and the progeny of earlier arrivals. In previous years there were reports of some individuals surviving the winter here (Newhaven Tide Mills was mentioned quite a lot). However, the larvae, which would be the overwintering stage, are very susceptible to cold and wet. It will be very interesting, though, to see whether we get a native spring brood appearing; it will all depend on what sort of winter we end up having. The larvae feed on various legumes, and clover is one of the most often used, but they also love Lucerne (Alfalfa), and fields of this crop will attract them in big numbers.

CloudedYellowgraphCloudedYellowgraph