Living in Essex as I long had, I had never seen the Emperor, he who had not been seen by anyone for years, and no one expected him to visit. Indeed, he only ever appeared to his most devoted followers in a small area of central southern England. It hadn’t always been so, Victorian enthusiasts had come out to many local places including Weeleyhall Woods to catch his kin and place them in collections in glass cases, mummified by the use of camphor. What an ignominious end for such a Butterfly. The Purple Emperor.
My diary informs me that it was in 2001 that I went on a trip to Sussex, not with nets and ether to kill such an animal, but with the naïve hope that he would come down from the treetops to pose for a camera. This was the first time I saw him, pointed out by other followers; he was sitting well up an oak tree, visible with binoculars, fairly large with a pattern of light and dark browns and a few even darker brown highlights. A large false eye pattern was barely discernible. Not really the vivid spectacle that his majesty’s devotees spend entire July months searching for. Where were the Emperor’s fabled clothes?
Starting perhaps ten years later, there were reports in the media that this butterfly was expanding its range. I learnt of a place in Suffolk where people had observed him, so I set off with some friends, and found the place. This time the empress put in an appearance. She was indeed a very large butterfly, rivalling the Swallowtail to be the biggest species in Britain. However, she never has the attire of her mate. She was tastefully patterned in chocolate browns and whites. She is also not fussy about particular plants on which to lay her eggs; she chooses the humble Goat Willow, a tree despised by foresters as it has no human use, and as such was usually removed. This is probably a major cause of the scarcity of this butterfly.
Another year, I returned and finally received a tantalising glimpse of his majesty, but had he got these legendary clothes? Generally, he sits towards the top of a tree looking out for a female, emerging from a pupa lower down on the willow tree. He will take flight to at times fence and spar with rivals. I saw him doing this, occasionally displaying a fleeting glimpse of the amazing colour, I would call it deep royal blue rather than Purple.
Neither males nor females need to come down to flowers for nectar. They are thought to normally take honey dew from the trees. However, they do run short of minerals, so they are well known to come down occasionally to damp ruts, or famously to piles of animal dung, to sip the moisture containing the salts they crave. So where were the Emperor’s clothes? He was rather smaller, brown and white like his mate though, until viewed from a suitable angle with the sun shining. Ah there was the attire that makes this butterfly particularly charismatic. This striking colour is an iridescence, the result of reflection of light from a set of scales critically spaced on the wings. It is not a pigment.
Over the last ten years, news of the expansion of the Emperor’s range, has been logged all over the country, reaching Epping and Hatfield Forests in Essex first and advancing further north and east. 2018 it was seen just across the River Colne in Friday Wood, last year at Alresford, and this year in Stour Wood Wrabness. I have been seeking an appointment with his majesty in my location preferably at Great Holland Pits, my ‘patch’, and I expect that the encounter will indeed happen, when he is ready. We have enough Goat Willows and I am propagating a few more to add to them. Holland Pits has more Grey Sallow another suitable food plant.
People ask why this species is expanding its range; it has been seen in Yorkshire I believe this year. Several butterfly species have benefitted from the warming of climate change. Another factor may be the return of Sparrow Hawks to our woods, as they thin out the numbers of Blue and Great Tits, which are very significant predators of the caterpillars.
I have yet to have had the perfect encounter with the Emperor, perhaps I have been so in awe and nervous that I have been too taken up with the great preoccupations with modern life, the perfect photograph or the anxiety about whether I have adequately supplied all of his needs on my patch.
Maybe next year I will learn to stop pacing around looking for an experience and enjoy nature as it comes. I think then it will be a matter of time before I am visited by his royal highness.