Three Purple Emperors feasting on animal dung. © 2021 Gillian Thompson.
Probably the most magnificent butterfly to be seen in Britain, the Purple Emperor is an enigmatic butterfly and is the second largest in Britain. The deep purple colouration of the male Purple Emperor is a result of light refraction by ridges on the wing scales. It is only visible from certain angles depending upon the direction of light. The females lack this colouration being primarily dark brown but with larger eye spots towards the rear of the hind wings. Both sexes have a broken flash of white across the forewings. The underside has a large eyespot used to deter predators.
It flies high in the tree-tops where it feeds on aphid honeydew and sap runs. They never visit flowers to feed but are often seen feeding on the ground on animal faeces, carrion or salts left as puddles evaporate.
Care should be taken as a low-flying Purple Emperor may be mistaken for a White Admiral.
The males are known to travel more than 1000 metres from their breeding areas, gathering in what are known as master trees where the males compete for females which are seen less often.
The Purple Emperor occurs in expansive broad-leaved woodland or in areas where there are clusters of smaller wooded areas where the larval foodplant is abundant.
The larvae of the purple emperor feed on Goat Willow (Salix caprea), Grey Willow (Salix cinerea) and Crack Willow (Salix fragilis).
See maps below. Distribution text required.