One of the rarer seen of the UK's butterflies. Partly due to habitat destruction (native woodland) and a lifestyle that sees them rarely descend from the tree canopy. Males will sometimes come down to feed on rotting dead animals, faeces, or muddy puddles. I've only ever seen one close up before today. The usual view of a Purple Emperor (@400mm and a hefty crop) At the mud-puddle So why are they called 'Purple'? Unfortunatly the purple colouration only shows if viewed from the correct perspective. The area between the body and the white band shows a vivid purple colour in the right light. Sadly I didn't catch it this time, but now I know where they are , I can get another go during their short flying season.