Great British Lepidoptera

Pale Clouded Yellow

(Colias Hyale)

The butterfly has been known in Britain since 1775. Sometimes it arrives in May with the Clouded Yellow but it is a much rarer migrant and there are long gaps between the years when it is common here. In 1947 it was comparitively common but its numbers here have never exceeded the 2,203 recorded in 1900. It is very similar to the Clouded Yellow but apart from its lighter background colour, the Pale Clouded Yellow has narrower and more broken black margins to the wings. The two like the same flowery meadows but the Pale Clouded Yellow, although a swift, strong flyer, never travels as far north as its relative.

In some years the early migrants reach Britain in time to produce a generation that is on the wing by August or September. These may lay eggs but the larvae have only a slight chance of surviving the winter unless they are artificially reared. It is the damp weather here that is their enemy.

In 1947, the Belgian Lepidopterist; L.A Berger described the butterfly that is now called Berger's Clouded Yellow, but was previously regarded as a form of the Pale Clouded Yellow. Because of its different caterpillars and foodplants, the butterfly was designated a separate species.