Purple Emperor

The Purple Emperor, Apatura iris

This is one of the UK’s most eagerly sought-out butterflies, and one of the good places to look for it is in Dene Park, the woods in the north of Hadlow parish.

Description

This is a stunning and generally secretive butterfly, that occasionally shows well on woodland paths when the adult males come down to either rest on paths or take up salts from dog droppings, from puddled clay surfaces, or even from carcasses. When it does come down to ground level, it can be quite insensitive to passers-by (dogs or humans), and good photographs can be obtained:

A male photographed in Dene Park, Hadlow on the 8th of July, 2019.

The female is a large butterfly with patterns of dark brown black over the upper side of the wings with white markings, and also some smaller orange eyes and splashes near the tail, but is rarely seen unless egg-laying on lower sallows. The male’s upperside is very similar, with perhaps slightly smaller white markings, but it has a purple irridescence that can be seen only when the light is just right. The males are generally the individuals which give good views.

This is a picture of a male with the further wing quite clearly showing the purple irridescence:

The same male photographed at Dene Park, Hadlow on the 8th of July, 2019.

The irridescence is by no means always visible, and here is a picture of the same male from a different angle, just a few seconds earlier. This is a much commoner “view” of this butterfly.

The same male photographed at Dene Park, Hadlow on the 8th of July, 2019.

When the butterfly closes its wings so that underside patterns can be seen, there is a completely different colour pattern to be seen, with more orange and grey hues to be picked out:

The same male photographed at Dene Park, Hadlow on the 8th of July, 2019.

Distribution

In the parish it is thought that it lives and breeds in the wider woodland complex of Golden Stable Wood, Carroty Wood, Frith Wood, Clearhedges Wood and Dene Park. However only Dene Park is open to the public, as it is an open access wood owned and planted up by the Forestry Commission. The rides, clearings and car park area are therefore thronged by butterfly hunters in early and mid July, hoping for a sighting of the elusive insect. However the butterfly does wander a bit and there are occasional sightings of it in gardens and other sites, sometimes at a little distance from what might seem to be suitable habitat.

This is a butterfly with a stronghold in the south east of England, in counties such as Hertfordshire, Essex, Hampshire, Surrey, Sussex and Kent.

Life Cycle

The butterfly depends on the Greater Sallow (Goat Willow) trees as a larval foodplant in the UK. Luckily this tree is a significant component of the woodland canopy in these woodlands. Oddly enough, Poplar is the favoured foodplant on the European continent. The eggs are laid on the tops of the leaves, and the tiny green caterpillars start to feed off their leaves until they turn brown and hibernate often just by the terminal buds. In the spring they turn green again and resume feeding until they pupate within a green chrysalis which resembles a dangling leaf quite remarkably.

The adults emerge at roughly the end of June and early July. They spend much of their time high above the woodland canopy, the males only sometimes descending to feed off the salts in faeces, puddles or clay surfaces. They don’t generally tend to be seen nectaring off flowers at all, but rely on the honeydew up in the canopy or the occasional sap run on a damaged tree trunk. Males may often come down to tracks to feed, but females spend most of their lives in the tree canopy, favouring dense and mature oak woodlands, coming down only to lay their eggs in the small sallow bushes that grow in clearings and rides

The males tend to “lek” around some of the taller trees in the wood, and meet their females there. These are generally not the very tallest trees, which would be too exposed to the wind, and the butterflies may remain faithful to particular branches or even clumps of leaves in their chosen area year after year, congregating in reasonable numbers within the spread of their few favourite trees.

Oddities

Perhaps the strangest thing about this butterfly is its devoted following among butterfly enthusiasts! Yes, it has a fascinating life-cycle, yes its impressive and very large (the second largest UK butterfly after the Swallowtail), yes its very colourful when its exactly at the right angle to the light, yes its very unpredictable (it spends much of its time as an adult high up in and above the canopy of the woodland trees it frequents) and yes its very, very difficult to get very good photographs of. However, there are other butterflies that are equally fascinating, and the incredible efforts that some people expend in order to pursue and photograph it are remarkable!

Predators and parasites

Oddly enough, several males do get killed by being run over when feeding on road-kill!

The same male photographed at Dene Park on the 8th of July, 2019.
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