You may have wondered how bright yellow male Brimstones can hide themselves from predators. Well, they go into brambles, evergreens, shrubbery or hedgerows and hang below leaves pretending to be foliage, where their distinctive wing-shape look like drip-tips of leaves. Their undersides are greener than the yellow upperside (which gives the bright yellow colour in flight) so they become remarkably difficult to find. I saw this one disappear into a bramble patch today when the sun went in and had to look hard to find it, the wing-shape finally revealing the location.
Not sure what Blogger has done to the colours, they aren't this lurid on the image that I uploaded.