Benjamin

[Benjamin]

Time to dive in and start a diary.

I’ll kick it off with my favourite butterfly related quote from one of my favourite authors (I don’t know many TBH - I’m not well read).

“I confess I do not believe in time. I like to fold my magic carpet, after use, in such a way as to superimpose one part of the pattern upon another. Let visitors trip. And the highest enjoyment of timelessness―in a landscape selected at random―is when I stand among rare butterflies and their food plants. This is ecstasy, and behind the ecstasy is something else, which is hard to explain. It is like a momentary vacuum into which rushes all that I love. A sense of oneness with sun and stone. A thrill of gratitude to whom it may concern―to the contrapuntal genius of human fate or to tender ghosts humoring a lucky mortal.”

Vladimir Nabokov

Despite reading rather a lot (by my standards) on the topic of butterflies, nothing ever really came close to adequately describing the feelings that butterflying engenders in me, and then I read Nabokov who described it exactly.

I think this diary will focus on my ongoing study of Purple Emperors in Sussex woods. I say ‘study’ but it’s really just a personal attempt to get to know the species, gathering plenty of data along the way. I have searched many iris woods over the past 2 and a half years looking for larvae, and have settled on 3 hotspots. The main centre is of course the mighty population at Knepp but despite the high number of larvae that must exist there, finding them is particularly challenging - at least in my experience - but I won’t go into all that now.

Last year I followed 60 overwintering larvae across the sites, observing a 75-80% mortality rate during the winter months (Dec-mid March (when feeding recommenced)). Those that survived were tracked for as long as possible. Three were followed to pupation (one of which was taken into captivity for close observation (more on that later)), one of which disappeared after a couple of days, and the final one was monitored in the wild until eclosion - an event I managed to film on my phone (I do attempt decent photos from time to time but am increasingly travelling light finding that my phone camera is perfectly sufficient for my needs (and I’m not very good with a DSLR truth be told)).

But this isn’t a write up of last year - that would be too dull, and I’ll keep it for a final report at the end of the project/study/faff around - whatever you prefer.

Best to jump straight to this year and report on the larvae I’m currently following. I have 35 under observation. Hopefully a few readers will find regular updates interesting, especially over winter when the diary updates tend to be thin on the ground. From my side I’m happy for any comments/discussion/suggestions (I know there are some iris experts that will read this!), but equally happy for people to browse every now and again without posting anything (I do that with many PDs and thoroughly enjoy them, which is in fact what prompted me to make the effort and play my part).

This year’s theme is characters mentioned in Dylan songs (last year Heavyweight boxers) - at least for the 20 that were found before Dec 1st. Those added throughout the winter are extras and would distort the overwintering data somewhat (obviously the later I find them the more likely they make it through) if they were to be included in that part of the study.

I’ll list the 20 and add some pics of a few (if I can figure out how to do that)....

1. Lily
2. Big Jim
3. Rosemary
4. Frankie Lee
5. Marcel
6. St. John
7. Ramona
8. Miss Lonely
9. Corrina
10. Mister Jones
11. Johanna
12. Dr Filth
13. Mr. Clean
14. Tiny Montgomery
15. Skinny Moo
16. T-Bone Frank
17. Ophelia
18. Billy the Kid
19. Estelle
20. Hollis Brown

These were found at various stages, from freshly laid eggs right through to overwintering larvae - all were present and correct on Dec 1st.

Billy The Kid

Billy The Kid was a rare ‘leaf dweller’ for a month or so but has recently relocated (keeping on the move of course) to a more standard location:

Billy The Kid relocated

There’s a much more noticeable size range this year - the majority are on the small side with Skinny Moo here seeming tiny in the flesh. X4 is standard ‘full size’ and is shown here for comparison.

Skinny Moo

Small but very pretty

X4

X4

Ophelia - one of several fork dwellers

Lily - followed from egg

X7 - fissure/crack dwellers seem to do well

Ramona - my only leaf dweller this year

A full check was carried out at the start of Jan - which I will report on next. Last winter 5 of the 20 boxers were lost in December.

To finish, here’s the video of the wild female emerging last summer - taken up a ladder (where I stood from 8 until 4 when she finally flew off!) and in rather windy conditions. You should be able to adjust playback quality if it looks really bad - although it was on my phone so not brilliant anyway.

https://youtu.be/Sh7FJimWLU4

[Max Anderson]

Delighted to see you've started a blog! Very keen to see how things develop. I enjoyed the Nabokov quote, I'm a fan myself - Recieved a copy of Nabokov's blues for Christmas. Fantastic video footage too, nicely done!

I also dropped you a private message..

[bugboy]

Fantastic stuff Ben. Really looking forward to seeing more of your posts

[trevor]

A warm welcome from me Ben.
Great work finding and following the development of the Purple Emperor larvae.
Fascinating video of the emerging female. Very few of us will see that wonder for ourselves.

Hope to see you around in 2021,
Stay safe, and all the best,
Trevor.

[millerd]

Amazing video, Ben - it was a bit windy, wasn't it!

Cheers,

Dave

[Wurzel]

Really interesting reporting Benjamin and that video is a cracker - she was quite a tease and I love the way the wings tips still seem a bit floppy right to the end Looking forward to the next report

Have a goodun and stay safe

Wurzel

[Benjamin]

Thanks for the warm welcome folks - really glad to know that a diary so limited in scope will still be of interest to some.

Before I report on losses (always a somewhat depressing task) I’ll take the latest lockdown as an opportunity for a case study or two.

As I’ve already linked to a video of her eclosion, I’ll start with B29 (when I first met her I’d long since run out of current heavyweight boxers and had adopted a simple numbering system). Such a magnificent beast emerged that I now look back and think the name most fitting - I’d like to think, and it seems a fair bet, that some of the Dylan characters I’m now following were eggs bombed all over the site by B29 when she routinely blocked out the sun on egging missions back in July (actually she wasn’t a particularly HUGE female but that would rather ruin the comparison - never mind).

Anyway - here she was around this time last year - a late find but a welcome addition to the stable. On caprea and lined up next to a bud - most of the caprea feeders seem to select buds.

In the early spring warmth of the 18th of March she began to nibble the freshly emerging leaves poking out of the bursting buds - an early starter - others in the area would still be unmoved a full month after this date with leafing time varying widely across the site.

Unfortunately she must have then remained unremarkable for the next couple of months, as I can only find a few hastily taken record shots of her progress. Here she is in her new L4 skin on April 15th.

Habitat at around this time

B10 was getting all the attention at that time, racing ahead in the fine weather and leading me to make the somewhat embarrassing rookie suggestion that a May iris could not be ruled out! Here he was on the 4th of May - well into his final instar and showing no signs of slowing.

To my considerable frustration I lost track of him soon after this, and so will never know if he made it, and if so when he emerged. I did soon learn however, from other case studies, how instantly cool weather can halt proceedings, and just how long pupation and other delicate processes can take under such conditions. If he survived I guess he emerged towards the end of the the 1st week in June.

But back to B29. L5 was achieved on May 5th and here she is fattening up but still 10 days prior to pupation.

https://youtu.be/R5DTJjRPZVQ

On the 27/28th of May she selected her pupation site and moved to the underside of the leaf. This would be an unthinkable breach of the caterpillar code at any other time, but now in late May with excitement permeating the sallows and a growing sense of rebellion in the air, the shackles are finally broken in an act of defiance (‘Going Underleaf’ The Jam called it I think) I like to think represents the passing of the caterpillar stage.

This photo of the prepupa is not the clearest, but does give a fair representation of her excellent camouflage at this stage, with her now pale green body closely matching the appearance of the furry caprea underside.

Two days later and a few hours before the final caterpillar skin is discarded, the pupa, and particularly the cremaster can clearly be seen within.

The next day, May 31st, I found the freshly revealed pupa as expected - I’m sure the change occurred late afternoon on the 30th.

I monitored the pupa closely after two weeks, knowing that eclosion could then occur at any moment. The cold spell at the beginning of June slowed development considerably however, and after a ridiculous amount of time invested in looking for subtle indications of development, it finally became apparent that eclosion was imminent on the 23rd of June. In fact it occurred on the 24th, some 24/25 days after pupation! I have already posted the video, but here are a few photos of pupal development.

5 hours before eclosion

30 mins before eclosion

I was very keen to see how she’d behave upon eclosion. Males sallow search intensively in the early part of the season, presumably hoping to locate freshly emerged females, but as I’d only seen two males in the area up to this point I certainly wasn’t holding my breath, and as expected no males were seen - in fact no males were seen at all after this point. After drying her wings she gradually repositioned herself on suitably secure vantage points working her way slightly higher up her branch until eventually taking to the air around 4 30, some 3 and a half hours after eclosion.

Although she started feeding early in spring, by mid L5 she had fallen back to the mid field in terms of development, and given that she was female, and after more than three weeks as a pupa, I was fairly sure that after her eclosion there was very little in the surrounding area still to come. I saw egg laying females on two occasions over the following weeks but nothing else.

Next up Deontay - the Bronze Bomber was on the same small sallow as Tyson Fury.....

[Benjamin]

Please let me know if the photos don’t display properly BTW - I’m using some hastily downloaded compression app and I’m not convinced I’m choosing the correct options! Really need to get a laptop. Thanks!

[Pete Eeles]

The images look superb, Ben, and what an amazing set of observations! Can't wait for the next instalment

Cheers,

- Pete

[David M]

Please let me know if the photos don’t display properly BTW - I’m using some hastily downloaded compression app and I’m not convinced I’m choosing the correct options! Really need to get a laptop.

Everything has come through perfectly, Benjamin. First class sequence. I particularly enjoyed the clip of the adult emerging from the pupal case.

Looking forward to seeing much more. Excellent observations.

[Benjamin]

Thanks for that Pete and David -

The boy Deontay will be my second case study. One of the early finds back in November 2019 and representing something of a breakthrough in terms of understanding this particular iris breeding ground.

When I first began searching for immature stages I sought out suitable looking capreas in iris areas, and drew a blank day after day. It was only when I switched to cinerea type trees, often in classically ‘unsuitable’ locations that I started getting results - a lesson in taking expert advice on board, but not rigidly sticking to it.

Salix caprea is generally listed as the primary foodplant but at the sites I study, Salix cinerea is favoured. They do occur on both (the previous case study B29 was a caprea feeder), and willows certainly readily hybridise meaning any exact analysis is well beyond me (hence I really mean cinerea ‘type’ when referring to cinerea). My guess is that they use both readily, and it just so happens that cinerea are favoured at my sites for other reasons (age, location etc).

Despite the well documented superb camouflage at every stage on caprea (there’s no shortage of photos with plump L5 larvae perfectly lining up their markings with the caprea veins), I find the camouflage on cinerea to be even more impressive. After hundreds of hours of searching both I’ve come to the conclusion that they’re harder to spot at every stage on cinerea and this probably accounts for the bias in the literature.

But back to Deontay - here he is in November, having just selected his winter resting spot. He’s on a small cinerea type tree in a fairly open location. This small sallow also hosted Tyson, Wladimir, Joseph and B17 and must be considered a prime location by passing females.

He stirred from his winter rest around mid March and was feeding readily by April.

A week later and his L3 winter outfit starts to look its age. I think Matthew Oates describes this as the ‘distended vegetable look’ - a good description.

By the 3rd week in April he had progressed to L4. I had wondered, having only followed cats on caprea up to this point, how such large caterpillars would cope with such small leaves (ok he’s not so big at this point) but I think this photo shows just how wonderfully effective the camouflage is - the horns beautifully mimicking a stem with the whole caterpillar looking like an entire leaf. I had also wondered what purpose the horns served, but am now content that although they may well be multifunctional (see below), they could be justified on camouflage grounds alone. There really isn’t very much to pick out when searching for cats by scanning a mass of small cinerea leaves - my cinerea feeders always take longer to relocate, even though they were often exactly where they were supposed to be.

I was so impressed by Deontay’s glorious L5 outfit (revealed May 4th) that I permitted myself a few close up shots. Unfortunately I didn’t have a lens that could do both so I had to settle for context and detail in different efforts. After the photo shoot he ate his L4 skin - something I’ve read doesn’t usually happen, but in my experience, generally does.

By the 3rd week in May Deontay was nearing pupation. MO paid a visit and demonstrated his considerable field craft by quickly relocating him after one of his daily position changes.

At the risk of further labouring the point, a few pics of Deontay, fully grown, and still blending superbly into his surroundings - the horns again adding considerably to the overall effect.

A few days later and most unexpectedly Deontay was under attack! I’ll save myself some time and copy and paste from an update I posted elsewhere at the time:

“Once again spent some time relocating and monitoring caterpillars today. Having just watched Deontay return to his seat leaf and perform his ‘settling down poo’, I noticed a large Tachinid type fly flying very deliberately through the sallow foliage. In a flash it landed on Deontay, scooted around from one side of him to the other and then departed just as his horns came thrashing down in defence. I considered whether it had had time to lay an egg, but decided it probably hadn’t, having watched Tachinids laying on peacock larvae several times and assuming the process would be similar.

I went to check on others, and then came back to Deontay a couple of hours later. Unfortunately there was now a very suspicious looking object stuck to his body. I don’t believe this occurred during the first event, so believe the fly returned having confirmed its target with the recce trip.”

Ah yes - another function of the horns is to keep things from sitting on your back for too long - apparently successful initially but ultimately unable to defend from a particularly persistent assault.

15375810-EC1C-4707-85E4-5C603FACF64D.jpeg (94.45 KiB) Viewed 47619 times

It was very difficult to decide how I felt about this event. I do tend to become very attached to these caterpillars (naming them may be a mistake), and the thought of Deontay being consumed from within was troubling to say the least. BUT, parasitism is endlessly fascinating, and what else am I doing spending so much time in the field if not attempting to further understand these potentially significant ecological interactions and relationships. In the end I decided to take Deontay into captivity and monitor events. Having consulted a Tachinid expert I was sure that Deontay’s days were numbered and wanted to photograph the fly that would emerge in his place. I had decided I would photograph it and let it go - not kill it instantly, pin it and send it for analysis as everyone else seemed to be suggesting.

With the ‘Deontay complex’ (for now surely he was not alone) in captivity I continued checking on the others and found a further two Tachinid eggs, this time firmly stuck to B16.

I very much wanted to photograph a pupa amongst cinerea leaves, and as B16 represented one of my last chances to do this, I decided to leave him/her in place and then perhaps collect the pupa if I managed to locate it.

Much to my surprise, and now hurriedly trying to get to the end of this long post, both Deontay and B16 developed normally! Evidently the Tachinid attack was unsuccessful. Although possible the eggs were infertile it is much more likely (according to the expert) that the iris internal defences (encapsulation response) were simply too strong for what must, therefore, have been a generalist Tachinid that would do well to steer clear of royalty and stick to peasant prey in future!

Some pics of Deontay to finish. He emerged after 23 days as a pupa. He was very willing to be photographed/filmed, even taking a short circular flight before landing and posing in a new location for a 2nd session - I feel like we went through a lot together!

https://youtu.be/Xbc5yP4mF84
Should play in 1080p60

[Neil Hulme]

I'm loving this PE cat thread, Ben. Great observations backed up by great photography. These images will be invaluable in helping others learn how and where to look for larvae, particularly as you're breaking new ground and upending some established theories. That's what UK Butterflies is all about!
BWs, Neil

[trevor]

Dedication at it's best Ben, and may I say a third Iris expert in the making!.

The new season beckons, stay well.
Trevor.

[David M]

Delightful account, Benjamin. Must say I was rooting for 'Deontay' myself reading that, and such a joy to see the happy ending.

These reports are highly instructive and I only wish I lived close to an Emperor site so I could observe such things myself.

[Benjamin]

Thanks for your very encouraging comments Neil, Trevor and David.

A quick report on losses for December.

A good start with only 2 (of the named 20) missing. There is always the possibility that they relocated, and I have overlooked them, but I search thoroughly enough for this to go down as a bit of a long shot unfortunately. In spring/summer last year I checked the locations of all those lost over winter and none magically reappeared.

Last year 5 of the 20 were lost in December.

Having completed my autumn/winter searches within the study zone I have the hibernating population at about 60% of last year. It will be interesting to see the survival rate of this reduced population.


1. Lily
2. Big Jim
3. Rosemary
4. Frankie Lee
5. Marcel
6. St. John
7. Ramona
8. Miss Lonely
9. Corrina
10. Mister Jones
11. Johanna
12. Dr Filth
13. Mr. Clean
14. Tiny Montgomery
15. Skinny Moo
16. T-Bone Frank
17. Ophelia
18. Billy the Kid
19. Estelle
20. Hollis Brown

Of course nothing too interesting happens over winter, but I’ll add a few photos taken after a freezing night and during a morning of sun.

Tiny Montgomery

Rosemary

Lily

X4

X8

[Benjamin]

Just so it’s not all hibernating caterpillars, I’ll mix in other interesting bits here and there. Spending so long amongst the foliage I do tend to encounter other woodland wildlife that I would normally miss altogether. One such encounter was with a delightful dormouse when out searching for autumn larvae a few months ago.

Somewhat bizarrely he managed to end up hitching a ride on top of my head! I was picking my way through some bramble mixed in with willow, on the way to a particularly good looking spot for larvae, when I felt what I thought was some foliage become snagged in my hair. As I leaned forward and brushed it off this little guy plopped down in front of me. Clearly fairly startled, he posed beautifully for a few pics before regaining his composure and scurrying off along a collapsed old sallow.

I have no idea what kind of population there is in these woods, but having watched him navigate his way through the thin sallow branches so expertly, I can quite easily imagine him feasting on juicy iris pupae were he lucky enough to locate one in June/July. I have a feeling (very scientific) this one, which would have been a larger female than the one I watched emerge, suffered exactly this fate when it disappeared a couple of days after pupation. I spent such a long time tracking her (although she didn’t move very far as it happened), and it was such a disappointing loss, that I have to add a couple of caterpillar pics of her final week or so.

[Goldie M]

Hi! Benjamin, I've found your post fascinating ( welcome by the way )and an education, and your shots of the Purple Emperor fantastic love the shot of the Dormouse but I would have been in shock if it had landed on my head Goldie

[Wurzel]

I'm rooting for T-Bone Frank Great shot of the Dormouse Ben Almost all of the photos I've seen they've been curled up in a ball so it's really interesting seeing one uncurled as it were; is it just me or do their heads seem out of proportion with the rest of their body?

Have a goodun and stay safe

Wurzel

[David M]

That's some undertaking you've embarked on, Benjamin. It will be fabulous to hear how things develop and I envy you having somewhere not too far from you where you can observe these creatures like this.

What a bonus that dormouse was? I've seen a few desirable critters as a by-product of searching for butterflies (lizards, snakes, salamanders, etc) but never anything as attractive as that.

[Benjamin]

Thanks Goldie - glad you’re finding the updates of interest. It was indeed a shock - I hadn’t seen one until then - an unusual first encounter!

I’ll give you T-bone Frank @20-1 Wurzel. I pay out at pupation. If I lose him at L5 it’s money back, any time before then we assume predation and you lose your stake. Alternatively I’ll just buy you an extra beer at the social (if we can ever take such risks again) if he makes it.....

I bet you’ve encountered a long list of fantastic wildlife on your travels David - this hobby does take us to wonderful places.

Again just a quick report on losses - this time for January:

3 further losses were recorded - so 15/20 remain.

R.I.P. Marcel, Mister Jones and Estelle.

1. Lily
2. Big Jim
3. Rosemary
4. Frankie Lee
5. Marcel
6. St. John
7. Ramona
8. Miss Lonely
9. Corrina
10. Mister Jones
11. Johanna
12. Dr Filth
13. Mr. Clean
14. Tiny Montgomery
15. Skinny Moo
16. T-Bone Frank
17. Ophelia
18. Billy the Kid
19. Estelle
20. Hollis Brown

Although this is only somewhat better than last year’s 12/20 at this stage, only 1 of the extras I’m following was lost on top of this, and so the overall picture does seem to be suggesting reduced winter predation at this point. Matthew Oates is reporting very low predation for his monitored larvae (and he has a good sample this year) - so reason to be positive.

Tit numbers in the woods do seem to be down compared with last year, but this is just a vague observation with no grounding in anything of substance.

It’s obviously hard to say anything much about last year given that it was year 1 of gathering decent data but with winter losses at 75-80%, it could be that the poor season we experienced was largely as a result of high winter predation. I think the fact I had 50-60 larvae in hibernation also gave the general impression that the overwintering population was high, but again, as this was my first year gathering good data it may well be that this assumption was false. It could (and this would be my guess) be the case that last year the overwintering population was actually quite low - better than this year, but still representing a poor year (MO was reporting one of his worst years ever when searching for autumn/winter larvae in 2019).

My hope is that by monitoring 50ish larvae in hibernation every year (with particular attention paid to 20), I might start to get a feel (hopefully before I die of sallow searching boredom - at least male emperors have an instinct telling them that whatever they find will be worth it! My instinct in stark contrast is telling me that I’m not going to find anything of interest and I’m wasting my life) for the relative importance of the various factors that ultimately dictate the quality of the coming season. MO feels he can get a realistic read for survival rates with a sample size as low as 4. What I lack in this kind of purple intuition, I shall try to make up for with numbers.

No proper time for photography whilst furiously exercising my way around the woods, but I did stop to get a quick pic of T-bone Frank for Wurzel - not a good shot even for a phone, but at least he can see who he’s backing.

Make or break month underway - if they get through this they’re almost there.......