Benjamin

[bugboy]

Very much enjoying your observations and the unfolding iris saga complimented by your superb images

[Benjamin]

Update from the woods....

3 of the named 20 iris larvae were lost in Feb with Frankie Lee, Ramona and Dr Filth joining the list of the departed. Still better than last year’s 4 per month but with a further 3 from my wider sample disappearing also, there doesn’t seem to be the dramatically reduced predation of the smaller population that we had hoped we might see. Looking at the data for the wider sample we’re currently looking at a 63% survival rate compared to 43% at this point last year. This neatly matches the sample of 20 which reassures me that 20 is a good number for getting a read on the wider population. Depending on weather we should see feeding recommence towards the end of this month. Next update at the start of April will be with the final figures for winter survival.

List now looks like this:

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

A few photos.....

Rosemary is on an early leafing tree and may be the first out of the blocks...

Frankie Lee did a pretty good job of matching nearby buds, but apparently this wasn’t enough. RIP.

Tiny Montgomery

St. John - never in the running for the colour matching prize this year, but bright green seems to have worked for him so far...

X3 sporting a particularly nice mix of autumnal colours

Big Jim is a lovely blend of reds and greens but unfortunately his particular fork is never bathed in sunlight. Some gentle manipulation of the branch illuminates his top half but that’s the best I can do.

These are all fairly similar but colours can be wide ranging - I will do a separate post on the various colour forms I’ve encountered thus far.

Lastly, and falling outside of the Dylan 20 this remarkable caterpillar is unimaginatively named X7. Given his location and unquestionable genius I’m very tempted to make an exception and name him Bobby Fischer, but with chess grandmasters lined up as the theme for next year I’ve decided to resist. No - I’ve changed my mind - geniuses are always ahead of their time and I might change my mind about the grandmasters anyway, so I present Bobby Fischer.

Sometimes the shadows give him away a little, and the rain ruins the effect entirely (although he does then benefit from being immersed in a droplet), but in cold crisp weather he’s exceedingly hard to pick out. I photographed him in various conditions as the sun appeared and disappeared, but I couldn’t quite nail the perfect shot. I think I’d need to bend the branch over and use a tripod but that would seem excessive interference for a pretty picture (I shamefully snapped a small branch when checking on a caterpillar the other day), so these will have to do.

[Max Anderson]

From the data you have collected in previous years, are you able to tease out any predictors for predation? I've always presumed weather is the key factor in play (dictating predator activity), but wonder whether there is any interaction between weather and position/orientation/colour etc..

Your shots are very nice, and I particularly appreciate the inclusion of occasional shots showing the host tree, as it provides some useful context. Photographing eggs/larvae using handheld methods is super tricky - requires a lot of skill and persistence - particulalry when you're delicately holding a twig with one hand!

[Padfield]

In exile from my home hunting grounds, I'm going to be reliant on you, Benjamin, for my iris cat fix!

I'd be interested to know if you have any 2nd instar hibernators. This was quite regular in Switzerland, and indeed the first one I ever found was a spring 2nd stager. I think the flight season in the UK is much shorter (I've recorded adult purple emperor on 15th September in CH) and the onset of winter less sudden, so perhaps it's less common for cats to get caught short.

Looking forward to la suite!

Guy

[Benjamin]

Hi Max - I agree with you that weather is key - for a whole host of reasons.

Being able to monitor tit populations and activity throughout the winter would likely provide the data we need, but as yet I haven’t come up with a workable way of doing this.

This is only year 2 of collecting good data, and I suspect both years have been poor iris years. What has surprised me the most is just how low density the caterpillars are - just how few there are overwintering in the prime breeding grounds. It is of course impossible to know how many I miss in my searches, but with silked-on autumn leaves being a very reliable way of not only locating larvae, but also surveying out of reach areas, I’m becoming increasingly confident that when they’re there, I find them. This confidence only applies to the small populations of relatively isolated woods I should add - Knepp, for example, is too vast to even begin to try to understand. I do find and monitor plenty of larvae there, but could only ever hope to properly search a tiny percentage of the suitable sallows. Of course even in the smaller woods you do have to spend a lot of time on site during a crucial few weeks to use the dangling leaf method successfully (they don’t last forever), but so far I have been able to do this.

In terms of unscientifically fumbling my way towards some kind of feel for what might be going on (perhaps a good title for any eventual report) I could really do with a good iris year to occur now that I think I know what a poor one looks like!

Hi Guy - no doubt like many other readers, your PD delivered me a much needed regular fix of European butterflies for several years - in my case whilst stuck in London with very limited opportunity for butterflying. If I can repay the debt in some small way with iris updates then the ‘project’ can at least be said to have some kind of purpose!

I suspect you’re right about the reduced chance of caterpillars being caught out and hibernating in L2. I watched eggs hatching in mid July last year, and some were still not in hibernation by mid November! It really does seem an awfully long amount of time, to eat a really tiny amount of leaf. I tried on many occasions to observe any kind of activity but apart from some occasional head swaying I only ever observed them sitting still - a long lazy summer and autumn - reminded me of my student days. If I ever find one hibernating in L2 then he (it would have to be male) will only have himself to blame. Of the 100 or so I’ve found in hibernation so far all have been L3.

[Neil Hulme]

Another excellent report, Ben. I'm hoping that one of your caterpillars might one day make it onto the big screen.
BWs, Neil

[David M]

A riveting read, Benjamin. Shame for those that have been lost but it's incredible how any survive at all when one sees how they overwinter in such exposed locations (and often not perfectly colour-camouflaged!)

I guess once they get active again locating them will be rather harder?

[Benjamin]

Thanks Neil and David (and Paul that I missed earlier) - hopefully soon I’ll be reporting on development rather than simply winter losses!

In terms of relocating them, they’re not actually particularly difficult to keep track of. They don’t tend to travel far from their overwintering sites - all the important work of selecting a good location having presumably already been done. In L4 and L5 they will journey down to forks and investigate adjacent sprays, but at that point they’re large enough for it to be relatively easy task to imagine their movements and scan to relocate them.

They will wander off if you disturb them though, and yanking down branches to take photos is a sure way to end the relationship prematurely.

Of course when fully grown and looking for a pupation site they can travel some distance (attached pic) opening up too great a search area to hope to successfully relocate them with any regularity - you have to get lucky at this stage, or just be following enough to stand a chance in the numbers game.

Journey to pupation (bored 6yr old for scale)

[Wurzel]

That seems quite a distance for something so small Ben I found that bored 6 year olds often found renewed interest when Skittles became readily available

Have a goodun and stay safe

Wurzel

[Benjamin]

Thanks Wurzel - yes - I’m not above a bit of bribery. Or I suppose it’s just a case of keeping everyone happy - a bit like how I’m happy to take them to the playground, but only the one that’s overlooked by a nearby beer garden. Just good solid parenting.

Update from the woods (March 31st):

4 of the Dylan 20 were lost in March, so 8 now remain. You have to search very thoroughly before declaring a loss at this time of year, because larvae will readily wander to seek out the best buds. It’s always possible that I’ve failed to relocate one that’s moved but I do spend a good deal of time searching so am pretty confident my errors are minimal. Over the coming weeks I will check for feeding damage at the locations of all those lost as an extra measure.

Despite recording 23°C in the woods at the end of March, the sallows are still 1-2 weeks behind last year. Most larvae were feeding by this time last year, but so far only one has taken a first nibble.

The casualties this time were Big Jim, Ophelia, St. John and T-bone Frank so the list now looks like this:

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

I tend to think winter survival complete when feeding recommences, so still a week or two to go for most of them.

Again the Dylan 20 seem to neatly represent the figures for my wider sample (not surprising given that the total was only around 30 in my main area this year) suggesting about 40% survival at this point. We were at 25% at this point last year, but most were already feeding and racing ahead in the very early spring of 2020.

A word on some of the losses:

Big Jim was a lovely healthy full sized caterpillar (unusual this year) so I was very disappointed to find that he’d been the victim of a shieldbug (or similar) attack having made his move from fork to bud. ‘killed by a penknife in the back’ as the song goes probably wasn’t too far off unfortunately. This kind of attack is not unusual, or at least finding them in this state is not unusual. I have not yet witnessed the attack unfolding but have seen similar attacks on other species.

Shieldbug vs Buff tip

Unfortunately St John’s luck finally ran out too - his bold green outfit and stubborn refusal to colour match finally proving too reckless.

T-bone Frank was unfortunate. He did everything right but was unable to locate a suitably swollen bud on any of the twigs close to his hibernation spot. This tree suffered badly from drought last summer, and many of the lower branches are shrivelled and dead. He must have investigated many possibilities, gradually working his way further down his branch to try the opportunities that each new fork presented. I found him attempting to make a scar work as holding bay as he patiently waited for this poor sallow to spring into life. A week later he was gone. A thorough search of the area didn’t turn him up. It is possible that in desperation he travelled almost to the base of this sallow in order to ascend to a quite different part of the tree (I will search again for him), but I suspect his poor camouflage on the scar he was forced to wait at, made him an easy meal for a passing tit.

The undoing of T-bone Frank

Outside of the Dylan 20, Bobby Fischer was another disappointing loss. Why he failed to move I have no idea but perhaps he became completely obsessed with camouflage and ultimately sacrificed himself to his art. His desiccated corpse becoming harder and harder to pick out as it gradually shrivels into virtual invisibility. Quite the artistic statement. Surely a shame to shun the riches that would follow a successful metamorphosis, but what do I know - perhaps that was the point.

Exhibit A - What happened to Bobby Fischer?

I will reincarnate him amongst the grandmasters of next year - assuming one chooses a fissure of course.

As a point of interest he was very much alive in my last photos of him, so the algal/lichen growth occurred on a healthy body.

Next update they should all be feeding and we can start to think about flight season timing and quality. I’ll make some predictions that’ll turn out to be wrong - it’s part of the deal when studying this species.

[Wurzel]

Come on Tiny Montgomery Play park overlooked by a pub beer garden - sounds like you've not just read but written the book on solid parenting I'd never have twigged that Shield Bugs would have gone for cats in that way - fascinating and gruesome

Have a goodun and stay safe

Wurzel

[David M]

I truly admire your persistence and commitment, Benjamin. This is a fascinating (although somewhat rather macabre) narrative, but it reflects the machinations of raw nature, so we must accept it and simply hope that a few of these larvae will fulfil their cycle and go on to reach adulthood and give rise to a further generation, whereupon the cycle will begin once again.

It makes me even more respectful towards any butterfly that presents itself on the wing, for it has clearly undergone a major battle against many and varied adversaries whose intent is to kill it.

Good luck to all those that currently remain.

[trevor]

Well done with your continuing observation of those PE cats.
Hopefully, as you know where they are, you'll be able to find an adult emerging from it's pupae once again.
Your images of that event last year were mind blowing!.

Great stuff, Ben.

Stay safe and well,
Trevor.

[bugboy]

Once again some fascinating observations Ben, what I would give to live within walking distance of an Emperor wood as rich as yours!

[Pauline]

Really enjoying your diary Ben. How do you manage to avoid collectors in your neck of the woods?

[Benjamin]

Thanks all for your interest and comments as always.

I’d like to be walking distance too Paul, but it’s certainly true that the relatively short drive from Brighton is infinitely more manageable than battling my way across from Hackney.

I must admit, David, that despite regularly reminding myself how fortunate I am to be in a position to dedicate so much time to this, I don’t always look forward to every day in the field! But because it is so obvious that the more thorough I am with my searches, and the more comprehensive my observations the quicker I can begin to gain the insight into this species that I’m looking for, the commitment follows quite naturally. A half measure wouldn’t work. That’s not to say that all observations and records aren’t valuable (of course they are), but just that I’m trying to make sense of an entire site (as much as possible) and so I need to be as confident as I can, that I know what’s going on throughout it. I realise this sounds ridiculous for PE given what we know about its ecology already, but larvae aren’t actually THAT difficult to find and as the same conditions for egg laying are sought out year after year, it is quite possible to quickly understand a site to enough of a degree to enable a sufficiently accurate autumn larval search to be conducted over a surprisingly large area. Naturally this must occur while conditions for finding larvae are best ie when silked-on leaves give away their presence in late autumn/early winter.

Having said all that I’ll contradict myself by answering Pauline’s question by saying that if any collectors can find them then they’re welcome! I’ll put 20+ field days into the autumn search (and then more through the winter months) many of which will be blank while 2 or 3 larvae a day would be considered very good - I don’t think collectors would bother with that kind of return. Having said that, the two years so far have been in poor years - perhaps after a good egg lay it’ll be much easier but we’ll see.

Trevor - I hope to find pupae again this year as monitoring each individual for as long as possible is clearly the goal, but I’m not sure I’ll have the same drive to witness the eclosion that I had last year. I really wanted to follow one all the way, but having done that I think knowing the date of eclosion would be sufficient this year! Maybe I’ll change my mind if a find myself in that situation again - or else I’ll call you and you can come and monitor it!


Anyway - April deserves a mid month update (report from 15th):

Thankfully no further losses occurred in the first 2 weeks of April.

About a third of the field are now feeding, with the most advanced taking the first nibble around the 1st of April. Two thirds are still waiting for leaf break, sitting patiently by leaf buds watching flowers gradually bloom and fade - all very pretty but it must seem like an eternity when you’re waiting for some food after 5 or 6 months of gradual starvation! I estimate that those on the latest leafing trees will have to wait until the start of May to begin to feed, with buds showing no sign of bursting and the 4 week gap between the early and late leafers of last year, unsurprisingly looking likely to be replicated.

Rosemary

X3 leading the field

Tiny Montgomery

X1

Mr Clean

I only have last year’s data for comparison, but leaf break on a tree i monitor very closely (most number of eggs in both years) is exactly 4 weeks behind last year. This fits with the timing of my records for the first larva to begin feeding (on different very early leafing trees) - the start of March last year, and the start of April this year.

Of course with only two years of data I can’t say how this 4 week difference translates into ‘early’ or ‘late’ seasons according to the ‘norm’, but I would hazard a guess that last year was exceptionally early so should account for 2.5-3 of the weeks, and this year is somewhat late so should account for 1-1.5 of the weeks.

Matthew, however, suggests that we’re currently bang on schedule and that although the colder than average weather is slowing them down, they are often slowed by rain in April/May so although the cause might be different, the outcome is the same - fair enough.

I have very detailed records from last year, so should at least be able to tell where we are in relation to 2020, which should in turn enable me to predict the season with good accuracy at my site at least. The gap is currently 4 weeks and growing - at this time last year the most advanced were racing towards L5 (achieved around 25th April) - this year they’re L3 and progressing very slowly.

They were so advanced last year that at this point a May adult seemed quite plausible, but a cold spell in mid-late May arrested development considerably and what would have been a record breaking early year became merely ‘early’.

I’ll hold off from commenting on winter survival as too many larvae are yet to begin feeding.

As I mentioned silked-on leaves earlier, i’ll finish with a short video I made showing one such leaf giving away the caterpillar’s presence nearby. It was shot in a small block of woodland close to Knepp and Southwater Woods which makes up part of the Dragon’s Green Estate. Unfortunately my settings were wrong for close ups, but as showing the wider habitat and context was the point of this experimental piece, it doesn’t really matter. I am in the process of creating a series of short films of this style to show various species within the wider habitat context (I’ll hopefully do a better job of staying out of shot in the future!).

Make sure you adjust YouTube playback settings to 1080p or else the quality is too poor.

Warning - a film about a dead leaf is seriously niche!

https://youtu.be/1xfj5J2OvMI

[jonhd]

Bloody hell, Benjamin! That's astonishing. Talk about 'the long tracking shot' - you should enter it at the Sundance Festival.

BR, Jon

[trevor]

You must have A1 eyesight Ben!. ( as I once had ) I have found them all in your excellent shots,
but would have walked straight past them, unaware of their existence!.

As for viewing the pupae nearer the time, that's a date!.

I'll be in touch when the old railway improves, like everywhere else it's been too cold.

Stay safe and well,
Trevor.

[Wurzel]

Really interesting reading Ben and I think you have a bit of the X-man about you to be able to spy out those little critters! Interesting to read about the timings of the year - there does seem to be a feel that things are later this year...but then things were pretty early last year

Have a goodun and stay safe

Wurzel

[David M]

Warning - a film about a dead leaf is seriously niche!

Possibly, Ben, but it is seriously well put together (presumably using a drone?) and gives an excellent portrait of the general habitat, which is what you intended.

Great to hear there have not yet been any April losses, whilst it's also illuminating to know how much time can elapse between larvae beginning to feed depending on their location and the tree they are residing upon.

Fingers crossed for the next few weeks!