Thursday, May 31, 2012

Iris Catches Up...

Good news!  Iris larvae made the most of fine weather during the last 10 days of May to feed up and grow like mad.  In N Wilts they shot through the 4th instar and are becoming full grown now - only the weather seems likely to go into Jubilee mode (i.e. wet), which will slow pupation right down, or prevent it altogether.  At early sites (Sussex & Surrey) some may have pupated already. 

All this means that we are, at this stage, on track for a late June appearance - BUT everything depends on June weather as the insect can go through the pupal period in 2 weeks or get stuck in it for ages, as happened last summer when outdoor pupae were lasting an average of 28 days.

Correction:  My thanks to Derek Smith for pointing out that iris hibernates in the 3rd not 4th instar!  I have a mental block on this, as I got it into my head aged about 13 that the beast hibernates in the 4th instar - and I periodically lapse back into that mode.  Pleased to say that I've got this bit correct in a forthcoming article on iris larvae in the next edition of British Wildlife magazine (entitled Adventures with Caterpillars)...  I may eventually grow out of this habitat...

Monday, May 28, 2012

Final instar (or, The Emperor's Old Clothes)

In Switzerland, Aurelian has entered his final instar. Here he is, next to his old clothes.

I may lose track of him soon, as he wanders off looking for suitable pupation spots, but with luck I will be able to locate his pupa.


Monday, May 21, 2012


I lived for nearly 15 years in Michigan and did a lot of peeing in the footpaths there too. There are 5 members of the Apaturinae in North America but only 2 of them are widespread enough that a bloke working near the Canadian border can get to know...

Asterocampa celtis, the Hackberry Emperor and Asterocampa clyton, the Tawny Emperor are just as interesting as the European Apaturas and thus it’s possible to waste an equal amount of time sitting around watching them. In general they are smaller and faster. You get the impression that they are tougher too, dashing around all over the place, the males aggressively defending their patch against allcomers. Magic. Their hostplants are Celtis sp. the hackberries and the larvae are similar to Apatura larvae but are smaller and brown in colour. If you find a Hackberry tree, chances are you’ll see one or other of these little brutes. They must have a complicated parasite relationship because they can become over populated and defoliate an isolated stand of Hackberry.

A. celtis is double brooded in the north and A. clyton has a single flight, so it’s rare to find them on the wing at the same time, but it can happen. It’s the females that are a rare sight. Always larger than the males, they hide away in the tree tops, decending rarely to damp earth for moisture but vary seldom anywhere where you can see them. The males can be attracted to fruit, pee or damp soil. In fact a blue shirt seems to be an equal draw and if it’s a hot day (And chances are, it is!) a sweaty blue shirt will bring them down fearlessly. I’ve seen them chase Blue Jays, even a Goshawk, but to see these little butterflies aggresively chase a full size American pickup truck off a bridge is quite something.

 I used to take part in the North American Butterfly Association butterfly counts, a sort of one day manic competitive butterfly census within a limited 25 mile radius. Well, one year we were getting close to a record number of species and so the magic pee under a hackberry tree was employed to a nice fresh Tawny Emperor to the list!

Chris Rickards


Global Emperors #1 – Bretagne, France May 2012
I live in Bretagne, France (Brittany) these days and spend a lot of time sitting around on dirt tracks between the end of June and the beginning of August. Yup, neck cramped and eyes peeled, dribbling beer and taking a leak in the middle of the path, waiting for a passing Emperor. Here in Brittany we have two Apatura emperors, iris and ilia. A. iris is found throughout Brittany. If you are in the woods and you find a stream with sallow and a good mix of other mature trees around, you’ll eventually see a male Iris floating through, hugging the lower branches or cruising high between the oaks. Later in the day i’ve not only seen but heard females as they crash into the sallow on their way to lay an egg.

 I have a couple of favourite sites but i’m never suprised to see Apatura iris in the woods anywhere in Brittany. Apatura ilia is a rarer beast. I’ve only seen it at 4 locations and quite by coincidence, one of them is my back garden. This emperor uses Poplars as a host and from my experience it seems dependant on plantation polars, planted for harvest on wet land where nothing else profitable will grow. This far west, it is certainly at the edge of it’s range. I found a previously unknown colony in the French department of Finistire a couple of years ago, and that is about as far west as you can get in continental Europe, just south of Cornwall.

Apatura ilia comes in two forms, f. ilia, similar in many ways to the slightly larger Apatura iris, and f. clytie in which the upper wings are washed with rusty orange. Males and females come in both forms and it really is a pleasure to see them in any form. It’s four years ago now that i found my first Apatura ilia in the back garden. I wasn’t really expecting it, You don’t do you? But there it was, a fresh male f. clytie sat on fig leaf, 12 feet from my back door on my bloody birthday!! So over the past few years i’ve got to know Apatura ilia quite well. We have Poplars in the garden and that’s where the larvae grow. The males are quite predictable and we see them from about 11am to 2pm puddling by the stream and from then till 9pm or so they are high in the sallow and oaks, keen and alert to chase down anything passing by. I’ve found pieces of ilia wings scattered in the veg garden after a successful kill, probably by one of the grey wagtails which the butterflies regularly pursue from their high perch. Experimenting with bait, i’ve found cat food from a can left out for a day or two in the sun works quite well, as does urine and a simple wet spot in the dry soil.

It’s only the males that come down to these baits and only in the morning and early afternoon. But I’ve attrached the girls also. Now, i always assumed that females didn’t come to bait and so the first time i saw a female Apatura ilia feeding from my tropical butterfly bait ( Bananas, beer and sugar), i thought it a fluke. But the next day i had another, a different female ilia, feeding from the same sugared fruit and this time it was late, just after 9pm. It had been hot and dry for a couple of weeks and quite a few males were around but seeing a female is still quite an event. Seeing a female Apatura ilia f. clytie feeding from bait at 9pm on your patio after a couple of Martinis and half a bottle of Pinot, well thats a happy day. So here’s hoping for a bit of sunshine for the 2012 emperor season eh? We have the same weather as the South-west of England here and it hasn’t stopped raining for months now.

Chris Rickards, Rohan, France.

Sunday, May 20, 2012

State of Play: 20th May

Iris larvae in captivity on the Glos / Wilts border and in the wild in N Wilts are now all in the 5th instar - the last two changed out of the over-wintering 4th instar this weekend.  Some are now in the late 5th instar, and will change skin again very soon, but most need a few more days feeding.  They are therefore a week or two behind on the last two years BUT they are quite capable of making up for lost time given the right weather - and the right weather is at last arriving...

Here's a captive one who has just cast its 4th instar skin, which it wore for some 8 months -

Re Steve C's quandary.  I suspect his breeding bush came into leaf unusually early, in March, and that some larvae started feeding before the bad weather came along in early April, though other's didn't?  Hence the disparity?  My captive ones are kept deliberately on a late-leafing bush, so none started feeding during the nice weather in March as there was nothing for them to eat then. 

Advertisement:  The June edition of BBC Wildlife magazine has a feature on His Imperial Majesty (out soon...)

Saturday, May 19, 2012

Homing Instinct

Hello. Guy from Switzerland here. I've been following a single wild iris cat called Aurelian since he was an egg. In November he moved about 2.5m from his home leaves, onto a different branch, and hibernated (about 1cm long). In March he moved again, out to the end of his hibernating twig, where he waited for the buds to burst. On about 25th April he climbed into the nearest leaves and began gorging himself before shedding his skin shortly after 29th April. Finally, fat and happy, he crawled all the way back to his original branch, to a leaf-cluster in exactly the same position as the one his egg had been laid on and where he had fed up all autumn. He is now to be found precisely where he was throughout September and October and into the beginning of November. I estimate his length at 16 mm.


Monday, May 14, 2012

I think we may get a very protracted emergence season

My captive breed iris larvae are showing a remarkable variation in development progress. The larvae emerged from hibernation in March with a length of 10mm, give or take a millimetre. A couple of the larvae have hardly moved on from their hibernation state. They have not fully greened up and are no more than 12mm in length. Compare this with the most advanced larvae that are up to 23mm in length and a verdant green colour, picture below. If I had a way of accurately measuring the diffence in weights, without disturbing the larvae, then the difference would be even more remarkable. The larvae lengths today, in millimetres, were as follows: 23, 22, 22, 18, 15, 14, 13, 12, 12.

I think the fine weather in March induced some of the larvae to come out of hibernation early and begin feeding agressively. These cats have continued to develop quickly. The less developed larvae have effectivly become trapped in a partial state of hibernation due to the cold and damp weather since the end of March.

Pure speculation on my part but if this pattern is being repeated in the wild population then I suspect we will get a very protracted emergence season this year.

Thursday, May 10, 2012

Hampshire Goes Purple

We are delighted to announce that Hampshire County Council has chosen the Purple Way of life.  Here's the new sign for its (superb and superbly managed) Ashford Hangers NNR near Petersfield.  The design also shows the Edward Thomas memorial stone on Shoulder of Mutton down, sword-leaved helleborine and yew.  Edward Thomas himself, of course, followed the Purple Way. 

Monday, May 7, 2012

How's Iris Doing?

The current foul & abusive weather is due entirely to the horrific combination of widespread hose pipe bans / drought orders coupled with a Jubilee summer.  The track record of these, singly, in this country is dire, but add the two together and the situation becomes cataclysmic, even apocalyptic.  It may well be that the only decent weather we'll get all summer will be during the Olympics, when the nation will be glued to TV screens...

His Imperial Majesty is struggling rather.  Larvae in captivity and in the wild are still in their 4th (over-wintering) instar, whereas normally they are in the 5th instar by now.  But they have all but changed colour to vernal green and they are feeding, slowly but surely, and one of my captive larvae is trying to change skin.  So, slow but steady progress, but at this rate the imago wont appear before July (though it is too early for that sort of prognosis). 

But spare a thought for His Grace the Duke of Burgundy, who has to fly in This...