Purple emperor cat

[Padfield]

Brilliant! So this thing about lifting off the leaf to minimise the shadow from below isn't all it's cracked up to be!! (Referring to Matsukaze's post, which is now on the previous page).

Guy

[Matsukaze]

I had a long look at some sallows from underneath today, to try and assess whether PE could be found (by me or by predators) by looking for the shadow. The splay of sallow leaves is such that there are frequently shadows from one leaf across the leaf below - where the leaf above is still unfurling, it can cast a vaguely caterpillar-like silhouette on the leaf below. Any bird trying to use this method would spend a lot of time, er, chasing shadows, unless it had a pretty exact search image of the PE larva in mind. Even then, given how scarce PE is, I'd question whether the behaviour would be worth evolving.

Although we can tell a leaf shadow from the shadow made by the PE larva, I'm not sure it's a useful search technique for us, either, and think I just got lucky with the photo. It works for WLH, but elm leaves do not cast shadows over other leaves on the same branch.

I become more and more impressed with the level of camouflage displayed by the Emperor. I was never going to find the larva on the Somerset Levels where I was searching (it has never been recorded here) but on numerous occasions I did a double-take at groups of leaves which gave the impression of a PE larva lifting off the leaf.

[Cotswold Cockney]

Brilliant! So this thing about lifting off the leaf to minimise the shadow from below isn't all it's cracked up to be!! (Referring to Matsukaze's post, which is now on the previous page).

Guy

That may play a minor part but, these Apaturinae larvae HATE hot sunshine, particularly when laid up for ecdysis ~ skin chnages. Then they are immobile and cannot seek shade by moving elsewhere when exposed to the heat of the sun. That pose does have a real purpose..... to minimise exposure to the sun at the heat of the day.... The larva can position itself so that in effect it 'stands' on its own minimal shadow area when the sun is at its zenith overhead ... thus reducing the sun exposure of the more sensitive parts of the body of the larva. Over the years, I've studied these larvae and noticed that they will even lean towards the sun thus avoiding or at least much reducing exposure to their more sensitive body sides....
..

[Padfield]

Thanks for the comments and interesting observations. It's easy to see why this species has always cast such a magical spell over lepidopterists!

To update the situation on my three caterpillars, just in case anyone is interested in following their progress:

Five days ago I found that Julius had moved to a different resting leaf and that Augustus was nowhere to be found. He was certainly not on his original 'leaf island', nor on immediately adjacent concentrations. Nero was still in exactly the same position on exactly the same leaf he had always occupied.

Tonight I visited the woods at about 7.00pm and found that now Nero too had vacated his original perch. A little searching and I discovered him on a fresh group of uneaten leaves (all these photos are dark and blurry because a thunder storm was rapidly approaching and struck just before I left for home ).



He is still the smallest of the three by a long way, but is growing.

This is the resting leaf he vacated, with its very characteristic appearance:



And this is the silken web at the end, where he had stuck himself on:



Julius was still in the same place I last saw him but I think his skin now looks distinctly too big for him and suspect he has recently grown into a new wrapper:



I searched again for Augustus and found what I presume is him, some way away from his old leaf island. He was well out of reach of my compact under the darkening skies, but is visible here just to the right of centre:



I took this next picture with zoom and flash and think he is probably about to undergo ecdysis himself - he looks rather as Nero did when I first found him:



The flash shows he is sitting on a nice bed of silk - a necessary precaution before this skin change, given that there may be violent rain along with the flashes later in the night.

Guy

[Jack Harrison]

Guy

At least you have named yours after macho Roman emperors unlike Capt. Oates who named his (BBC R4) after poofy poets.

Jack

[Padfield]

Guy

(As you will have guessed, I did this because of the purple toga that the males will eventually be entitled to wear)

[Padfield]

Augustus survived the storm and changed his clothes:



Guy

[Padfield]

Julius changed resting leaves during the day today, just as I called in on him. The first thing he did on arriving on the new leaf was start eating around the edges, allowing my first action shots of these curious creatures:


(Getting restless on the old leaf)


(Tucking into the new one)





Guy

[Padfield]

My last post, on June 1st, was the last time I saw either Julius or Augustus. The next time I visited they were both nowhere to be seen, despite thorough searches. The daytime activity was unusual, so perhaps they were expecting a big change in their lives. Repeated searches have failed to locate them or any pupae.

Nero, the original subject of this post, has moved resting leaves for a second time (that is, just twice since May 7th). He has at least one more moult to go and is now at roughly the same stage Julius and Augustus were at when I found them, one month ago (May 17th).

This is Nero now (18th June):


(Still no sun in Switzerland)

And this is how he was on May 7th:



Guy

[Padfield]

One day later and Nero has once again laid himself up for ecdysis. This is his third moult since I found him. The dates of the moults are:

May 7th-10th (he was in the new skin on 11th)
June 1st-2nd (new skin on 3rd - might have started ecdysis earlier than 1st)
June 19th-

How many instars do purple emperors have? I thought they hibernated in the third instar, in which case he would now be entering his 6th.





Guy

[Padfield]

Spot the leaf that isn't a leaf...



Correct - slightly left of centre - meet Diocletian!



This has to be one of the most beautiful things I've ever seen.

The shape of the chrysalis is as leaf-like as possible, given the limitation that it has to contain a butterfly:



Even from quite close, the resemblance would fool most predators:



If anyone can give me a 'countdown' to emergence - how many days before emergence the colours appear &c. - it would be very helpful. The day I think it's going to emerge I will take a six pack, a chair and a book down to the woods.

Guy

EDIT:

And finally, this photo of Nero in close-up, preparing for his last skin change, shows the new skin under the old. And it shows him with an almost beatific smile.

[Rogerdodge]

If anyone can give me a 'countdown' to emergence - how many days before emergence the colours appear &c. - it would be very helpful. The day I think it's going to emerge I will take a six pack, a chair and a book down to the woods.

If it's July 8th, I shall supply the beer!

The species descriptions on this web site suggests 2 weeks, so Sunday 3rd July looks a good bet.

[Padfield]

The species descriptions probably don't reckon on single figure temperatures during the pupation period... To get to the woods I have to cycle down the hill a bit and at 11.00am today I was wearing a sweater and a coat and my hands were going numb, just like in the winter. Quite incredible. So, there is a distinct chance the pupation period will exceed the two week norm. On the other hand, I don't know when this insect pupated. I certainly can't say that because I didn't notice him before he wasn't there before!!

The one good thing about all this cold weather is that I've got nothing better to do than stand around sallows looking for leaves that aren't. Hunting these wonderfully camouflaged creatures is time-consuming!!

Guy

[Neil Hulme]

Hi Guy,
A couple of years back I watched two pupate in the wild. Both emerged after 19 days, although the temperatures were average for the time of year. With your temperature extremes you might get an iole - in which case I'll be hiring a private jet to come over .
The day before emergence you will see a very rapid colouring up of the pupa, with the white bands clearly visible. Expect them to pop out of the shell as first light breaks. Exciting times!
Neil

[Padfield]

Yippee! Beer at dawn!

Thanks, Kipper.

Guy

[Cotswold Cockney]

Guy, now it's obviously fully hardened off, try lightly touching the suspended pupa gently with length of grass leaf. Almost a gentle tickle....

These pupae can shake themselves so vigorously that the branch and even the bush will shake too. I suspect this is a defense mechanism against a foraging bird, mammal or reptile. These pupae can shake so vigorously that the surprise effect on any would be predator could deter them to take fright and retreat.

Two or three pupae on a bush shaking really is worth watching .... very effective deterent I think... and no chance of becoming detached from the strong silk pad the cremaster is embedded in ~ as anyone who has tried to remove a pupa will discover. When rearing numbers of Apatura species, to remove the pupae from their leaves I would rub the edges of their silk pad and work it away from the leaf leaving the silk attached to the cremaster of the now detached pupae. I then use some Uhu glue sandwiched with the silk between folded paper so that the paper could be pinned up so that the pupae could again hang at a natural angle essential for successful emergence...



Also in the frame is a card with three Salix caprea specimen leaves showing the typical eating patterns of the pre-hibernation A.iris larva. Find a leaf like that in late summer or autumn and you can be almost certain the insect occurs in that wood. I have sometimes found these both here in the UK as well as in mainland Europe's woodlands where I have never seen the adult butterfly ... Note that the leaf tip is still intact and uneaten. That's where the little larva rests when not feeding.
..


.

[Padfield]

Thanks for that, CC.

Here follows the worst video in the world - my present video camera is totally unfit for purpose and couldn't focus on the pupa. But it does show what CC was talking about, first in real time, then at 1/4 speed. I didn't want to do it again with a better camera (even my little compact takes better videos at close range) because a pupa only has a certain amount of energy reserves and I don't want to use them up for my own curiosity!

Don't blow up to full screen - it won't look any better!

http://www.youtube.com/watch?v=JJxRpJ5K4Mo[/video]

Guy

[Lee Hurrell]

That's amazing!

Quite a strong shake for what is essentially a container of fluids changing into an adult!

Fascinating stuff Guy and CC.

Cheers

Lee

[Padfield]

I'm checking every evening, so when I see the colour change I can be there at 'daybreak' the next day (at what time did your three hatch, Pete? Are we really talking 5.00am?) to film the emergence.

Tonight, I found another pupa, not far away. There is a non-negligible chance it's Julius or Augustus but I gave it a new name anyway: Constantine.


(Constantine)

This is Diocletian a couple of mornings ago. He gets the morning sun:




(Constantine)


(Constantine in situ)

Guy

[Pete Eeles]

Hi Guy - great vid!

As Neil says, the adults normally emerge early morning. I've probably bred a couple of dozen over the years, and they've all emerged between 0700 and 0900. Apart from one which decided to emerge at 1500 - definitely abnormal!

I personally find the "colouring up" very subtle. In fact, of all the species I've bred, this is the one that least shows itself through the pupal case. Just to give you an idea - here's a shot of a fully "coloured up" pupa. It emerged the following morning. A master of disguise to the last

Cheers,

- Pete

EDIT: Found a couple of other shots that also give a hint at just how opaque the pupal case is!