An Assembly of Emperors

This has been a very happy Easter for me because I have realised a long-held wish: to organise and then witness an 'assembly' of male Emperor moths attracted by the pheremone scents given off by an unmated female.

Loyal and tireless followers of this blog may recall at least a dozen posts over the last three years which have recounted the saga of a dynasty of Emperors established by the magnificent female used above on the blog's web page.  I have repeated her photo at the top of this post, because she and her offspring have brought me so much pleasure since she spent a night in the moth trap in early May 2014.

She left me a gift: this clutch of 25 eggs which hatched into caterpillars, at first small and black, then bigger and banded and finally huge and glorious in green with gay patterns of lines and dots. I described the ensuing saga two posts ago, ending with my hope of using my latest hatching - the lovely female below - to get male suitors to assemble.

I placed her gently in a muslin bag for the whole of last Thursday, took her to the grandchildren and repeated the experiment on Friday and then tried putting her out as mate-bait in the garden here on Saturday. Nothing happened, so towards mid-afternoon on Saturday, I transferred her to the outside of our shed/summerhouse where she sat in the sunshine, free to fly off but as uninterested in escape as she had been when in her muslin prison.

I was planting spuds and doing other garden chores with Penny and we both kept an eye on the moth, but neither of us noticed any arrivals. I know from others' reports and articles online that males do not always come and assemble, and so I was resigned to failure when I took my spade and rake back into the shed at teatime.

As soon as I went in, I heard a terrific fluttering and there was a male Emperor, beating his wings against one of the windows in obvious frustration. When he stopped, the fluttering carried on, and I found a second would-be suitor at a different window, My eye was then caught by a third. An assembly! But one thing puzzled me, and still does.

The moth literature credits the female Emperor's pheremones with attracting males from over a mile away. Their antenna - and look what majestic ones they have in the two pictures immediately above - guide them across country (and if necessary, town) to the 'calling' beloved. She moves the last segment of her body in and out, emitting what are clearly fantastic aphrodisiacs. Unfortunately, the human sense of small cannot detect them.

But while my female was on the outside of the shed, her three suitors had all flown in and although the door and two windows were open, they could not get out (I think on the lobster-pot or indeed moth-trap principle, that prey find going in through an opening much more easily than getting out).  What explains this bungle at the end of such an outstanding piece of navigation?  My best bet, drawn from descriptions of assembling males moving in on a female in a series of erratic circles (much as teenagers or young lovers may do), led them to fly into the shed and then get trapped.

Anyway, all was well as I captured them all and put them briefly into an ice cream carton where an orgy which would not have disappointed the sleazier sort of Roman emperor took place, as shown immediately above.  All three males did their best, crawling all over the impressively unfazed female, but only one managed to lock on - an appropriate phrase as when I took the lovers outside to the safety and comfort of a hawthorn hedge, they tumbled down several branches without coming unstuck in the vital place.

I always like it when young people can witness scenes from the natural world such as this (even if usually a little less hectic), and it was great that two of our neighbours' grandchildren were visiting for Easter. Especially as one of them was wearing a shirt whose motto summed up the apparent philosophy of male Emperor moths:

All four moths are now at large in the neighbourhood and I hope that the female will lay another brood of eggs to continue the story of this remarkable dynasty. Sadly, her generation will only have a couple of weeks left to play their part in this, as adult Emperor moths do not feed and therefore live only a short time.

Meanwhile, I have two cocoons left which have not yet hatched. Four years' slumber is not unknown, says Dave Wilton. So you may not have heard the last of this.  A very happy Easter to you meanwhile.