Purple Emperor (Apatura iris)
A. iris is best seen through the early morning and again during the late afternoon, when the males come down to the ground, on hot humid days, to take in nutrients from damp earth and animal droppings. They are also partial to human sweat - a key component of Emperor watching - and readily land on observers. Despite this ‘grounding’ behaviour, both males and females spend much of their time resting or feeding high within their arboreal home and out of sight.
The above image shows a male feeding on honeydew high in the oak canopy.