The butter fly

It is thought that the Brimstone butterfly (gonepteryx rhamni) was the insect that put "butter" into the word butterfly. When the wings are laid open, especially the male's, they are a bright sulphurous colour and Brimstone is an old word for sulphur. When the wings are closed such as this one, they appear green. These butterflies are the first to appear in the year and the last to disappear and they have the longest lifespan of a UK butterfly (up to one year).

I suddenly noticed this one in the garden!