Dangle Leaf Season Ends

Sadly, and annoyingly, Storm Bert (what a horrid name!) hastened the end of the 2024 Dangle Leaf season. 

I found this larva by Dangle Leaf on Thurs Nov 29th - a lone spinning leaf, which had fallen off by the following afternoon -  

In Savernake, the storm blew the foliage off nearly all of the 'late leaf fall' sallows, and removed any dangles those sallows might have held.  

All larvae are now firmly in hibernation.  

The good news is that woodland titmice populations seem very low indeed, with no rampaging flocks. We'll find out for sure when the Great Tits start setting up territory in the New Year...  Titmice are serial predators of hibernating Emperor larvae... 

Storm Damage & Pet Rescue

Storm Bert will have brought a number of older sallows down in the woods. Most of them will regrow, if left alone, as 'walking trees' (as in ' "Narnia awake! Be walking trees..." '). Few of them will be left alone, though.

Fallen sallows present a good opportunity to find and rescue Emperor larvae (either by rearing them in captivity or by tying snipped off larval twigs back on to safe sallows - old-fashioned wire plastic bag fasteners work well).  

A fallen sallow like this is likely to produce a couple of larvae, in or under the crown, at a rate of one every ~45 mins searching -

Crucially, few if any larvae fall off when the tree comes down - their feet are that well attached to the silk pads. Don't underestimate an Emperor caterpillar, just rescue it...

 

New Method of Finding Larvae...

Today, in the steep-sided wooded valley of the River Frome between Cirencester and Stroud, in it's-not-supposed-to-be-Purple-Gloucestershire, I became the first person (surely!) to find an Emperor caterpillar whilst having a pee! Completely by accident, but I always say: Look and thou shalt find, and I looked...

Here, he is, on a twig scar. He's called Willie -

So, never mind Dangle Leafing, we now have Dangle Willy....

The ultimate Purple micturation experience, though, came in 2011 when Neil Hulme was in midstream in the middle of one of the Fermyn rides, baiting, when Apatura iris ab. afflicta flew between his legs. Here's the offended butterfly -

On a more serious note, Storm Bert (what fool named it that?) could well end the 2024 Dangle Leaf Season prematurely.

 

Dangle Leafing Update...

Yes, the blog that brought you 'Dangle Leaf' now brings you 'Dangle Leafing', a term covering the art of looking for Emperor larvae using the Dangle Leaf Method... 

It's a bit like dry fly fishing for specimen Brown Trout on a southern chalk stream: a lot of wandering about, intense observation skills - and the last thing you do is cast...

Here's a particularly silly Dangle, but it is 100% Apatura iris -

But it was there one day, gone the next.

It is now half-time in the Dangle Leaf season here in the western reaches of the Empire: the leaves and dangles have come off the early leaf-fall sallows, and have all but gone from the mainstream leaf-fall sallows (more Emperoring terminology here...)

but the late leaf-fall sallows are still quite green. They are late to drop their leaves because they came into leaf last. 

These late leaf-fall sallows are likely to hold more larvae, because they were more attractive to the laying females, being thinner leaved in July... Crucially, they haven't started to reveal their dangles yet.

So the second half of the Dangle Leaf season here could be quite interesting... Of course, much depends on the weather - wind and rain take the dangles off, and the first half of November was marked by calm days.  

Most Emperor larvae are now in hibernation - apart from those on late leaf-fall sallows, many of which are still on leaf tips. So, to the woods, for the late sallows! You probably have until mid-December.

The best thing about the Dangle Leaf Season is that it takes the pain out of November! I used to dread this month...

Another story, this 'pillar was in hibernation on a curled terminal leaf back on Oct 19th - 

However, in mid-November s/he moved 3m to a bud, and changed colour. Don't underestimate a caterpillar, let alone an Emperor - 

It took me half an hour up a ladder to find it...

Numbers remain very low in and around Savernake, but Ben Greenaway is finding good numbers in mid West Sussex, mainly through Dangle Leafing. 

Happy dangling! 

 

Into Hibernation & Peak Dangle Leaf Season

Emperor larvae are now going off into hibernation. Those on early leaf-fall sallows are already in hibernation, favouring buds, forks and stem scars. 

Here's a typical one by a bud, from Savernake last Saturday - 

Here's one in a scar -

Larvae on late leaf-fall sallows, which are still green, are still on the leaf tips, though they are fully coloured up and ready to go. 

Larvae can go walkabout big time before finding a spot in which to winter - sometimes ending up close to where they started, after wandering many metres. However, it looks as though this year they are not wandering far.  

Here's a most atypical Dangle Leaf, attached to the stem by silk that's come detached from the silken highway spun along the leaf midrib! It wont last long -

The Dangle Leaf season is now in full swing, in the absence of rain and wind. Ben Greenaway found 22 larvae in a (long) day in West Sussex last week, nearly all of them via the Dangle Leaf Method.  

But the Dangle Leaf season may start to wane after the coming weekend, when squalls on a brisk northerly at forecast.

Dangle Leaf Season

The Dangle Leaf season is upon us! 

At this time of year, Emperor larvae change colour, quit their feeding leaves, and go walkabout prior to conking out for five months, normally by a bud or in a fork.

Crucially, they have silked their feeding / seat leaves on assiduously. The leaf petiole join then breaks, leaving the vacated leaves dangling on thin strands of silk, for an indeterminate while.

'Dangle Leaf' can be a highly effective way of discovering Emperor larvae, and a very useful survey technique; but it's rather like Floo Powder in Harry Potter...

First instar feed leaf dangles can be rather indistinct, and can be imitated by some moth larvae, and dangles on narrow-leaved sallows are particularly small; but occasionally you find clusters of first & second instar feed leaves, like these:-

or these:-

More usually, you find a vacated dangling part-eaten leaf like this:-

Most distinctive of all are the third instar feed leaves:-

This one's wrapped itself around the stem:- 

Note the broken petiole and the silk. That's iris, no one else does that (though spider silk can at times throw you). 

Dangles can also contain bits of leaf stalks, which have been silked on too:-

Note the silk on the stem:-

Dangles on narrow-leaved sallows last longer, but are smaller and easily missed.

Dangles on broad-leaved sallows are easier to spot, but get blown off by gales and washed off by rain - though some in sheltered spots may persist long into the winter. 

Dangles last better on sallows in the most sheltered spots, such as in gullies or on the edges of young conifer plantations.

The technique is to wander the woods on a day of good light with a gentle breeze, covering as many sallow stands as possible, and look for leaves - single or multi - spinning around madly in the air. Then home in on the 'pillar, which may be a few centimetres away, or a few metres distant. I carry a 2m long shepherd's crook. 

It's rather like dry fly fishing for specimen Brown Trout on a chalk stream: a lot of wandering and intense observation, the last thing you do is cast. 

There's a but coming up, and here it is: But there are early leaf-fall sallows, mainstream leaf-fall sallows and late-fall sallows (into early December), with much depending on when the first frosts arrive and sallow foliage health.

So, you have to do repeat-visits, checking regularly over a three week period. Sallows that have dropped 50-75% of their leaves are best, and ignore any that are still fully green (until later). Timing is everything.

This year the main Dangle Leaf season will probably run from November 11th to early December, but it may last till Christmas. Much depends on prevailing weather (don't venture out dangling after a storm, go before).

Enjoy... but beware of false prophets (many will come in my name): spider silk can sometimes generate Emperor-like dangles, Geometer moth larvae often silk-up small, usually uneaten leaves, and beware of broken stems. 

This is not iris (far too much white stuff and no eating on the leaf) -  

Halloween!

 Hibernating PE Cattie with a scary skull marking, from Knepp during the 2016-17 winter (it was last seen ascending a sallow as a big L4 larva on May Day). 

Pet Rescue!

Great to find and rescue two Emperor larvae on a recently fallen sallow yesterday - a tall broad-leaved sallow with 8m of trunk before any branches, which had crashed down over a busy ride and was destined for the chop (someone had already started).

It took the three of us an hour to search.

This shows, 1) that 3rd instar larvae do not fall off when their tree falls - such is the power of their silk pads; 2) that there may be a reasonable number of larvae high up, out of normal reach.  

I have a very good record of finding larvae on recently-fallen sallows...

All told, we saw 8 larvae yesterday: 2 in hibernation (one on a leaf, which is unusual, one on a bud), 2 almost fully coloured-up prior to hibernation, and the other 4 starting to think about it.  

The Dangle Leaf season will get going properly in about a week's time - we need a long dry and calm spell... Sallow foliage is lasting late this year, in the absence of frost - though sallows badly afflicted by Willow Rust have gone into early senescence (explaining the larvae found in hibernation yesterday). Watch this space...

Early Hibernation?

This 'pillar yesterday, Sat October 19th, was fully coloured up (complete with bronze V) and in pre-hibernation pose - about to quit the leaf for bud or stem (unless it had decided to hibernate on that terminal leaf).

Crucially, it had little choice as its sallow tree was 99% bare due to the ravages of Melampsora Willow Rust. How it had fed up to a decent hibernation size on such a depleted tree only the Good Lord knows...

Here's it's tree - 

For the record, the earliest dates I've recorded larvae in hibernation are 17/10/2010, 21/10/2016 and 23/10/2009 - all on early leaf-fall sallows.

 

Knepp 2024

Here's the data from the Purple Emperor transect at Knepp, which runs for 2km down an oak-lined green lane bordered by sallow thickets. It's a single species transect (ignoring all other species), which is walked once a week during the PE season, in afternoons only (from about 12.20), in decent weather (wind is a problem at Knepp), when males are on territory and, crucially, has a massive recording box, and takes about 3 hours:-  

 

This is good data. The UKBMS data is restricted to the standard 5m recording box and largely records males feeding on dog poo. 

The Knepp data suggests that PE had an 'average' year in 2025. However, counts during Week 1 and Week 2 were relatively high. Indeed, the 2024 Week 2 tally was the second highest for that week in the whole data set, only bettered by Week 2 of the 2018 annus mirabilis. 

What happened in 2024 is that the butterfly got systematically blasted away by spells of foul and abusive weather after Week 2. The Week 3 count was way below what it should have been. This is largely because the numpties insist in roosting in sprays in the oak tops, rather than on the leeward side of limbs... Had the weather not broken the annual total would have been in the region of 150-160.

Below are the PE season start and end dates at Knepp. Again, this is seriously good data, derived from diligent recording. This site is very well monitored.

First & Last Sightings at Knepp  2014 - 2024

        (earliest & latest dates in bold)

        2014    18th June     31st July

        2015    30th June     >21st July

        2016    27th June    3rd Aug

        2017    15th June    25th July

        2018    17th June    26th July

        2019    25th July    31st July

        2020    13th June  23rd July

        2021    2nd July     19th Aug

        2022    16th June    29th July

        2023    20th June    25th July

        2024    17th June    1st Aug

Just note how early PE starts there in this modern era, and ignore what the books say. Sooner rather than later a May iris will be recorded at Knepp...  

Only 2021 was a traditional year, with old-fashioned start and end dates.

Also note that PE has only been recorded in August during three of the 11 years.

Purple Emperor pages are being updated on the Knepp websites. 

  

 

  

 

Mid-October Doings

Purple Emperor larvae continue to be unusually scarce just about everywhere this autumn. All bar one recorder (Ben Greenaway) is struggling to find any.

Savernake is going to record its poorest autumn larval count in 16 years of diligent, standardised effort. This is primarily due to:- 

1  A shortage of the younger sallow growth that the females favour (i.e. trees or young branches off mature trees which are just becoming mature enough to flower). This is a problem currently peculiar to Savernake, which is experiencing a lack of sallow regeneration (in part due to squirrel damage - bark stripping, in part due to a break in continuity of ride widening).

2  Coarse foliage, caused by sallows coming into leaf early this year, after a mild winter. First instar larva can't cope with thick leaves. This is a problem everywhere this year.

3  The ravages of rampant Willow Rust, which has rendered many broad-leaved sallows seemingly unsuitable (+ Tar Spot). This is even worse around Swindon and Cirencester, but all but absent in S Warwicks & S Worcs.

4  But, clearly, the 'egg lay' was very low, at least low down.  

However, there is a scatter of larvae around. I was amazed to be shown one on a young sallow rendered 95% bare by the ravages of Melampsora Willow Rust - the small tree on the left, with my gold shepherd's crook. The finder, co-worker Gary Tucker, is looking at the bigger tree - 

That 'pillar is starting to colour up - 

It's not just Emperor larvae that are scarce on the sallows this autumn. Other sallow invertebrates are perhaps even scarcer: I'm scarcely finding any moth larvae, though some moth species may have finished for the season; Sallow Flea Beetles are decidedly rare; I haven't found a single sallow sawfly larva all autumn; the normally common cabbage-like galls of the midge Rabdophaga rosaria are rare, and even the tiny galls that normally abound on narrow-leaved sallows are generally absent; and I've hardly found any Dicranopalpus harvestmen spiders... In fact, the Purple Emperor is actually faring relatively well!!!

Fingers crossed that yet again this the best of all possible butterflies will show itself capable of out-manoeuvring all the nonsenses that gets thrown at it... 

 

Sallow Foliage Conditions...

Purple Emperor larvae remain seriously scarce this autumn: on Saturday, three of us found two larvae in some 15 hours of foliage searching in Savernake. One larva had only just changed into the 3rd instar - its old head was lying close by; that's late.  

Tony Kasiske reports a similar scarcity in Germany, again due mainly to poor flight season weather.  

Interesting to find a sizeable and healthy-looking larva on a branch heavily infected by Melampsora Willow Rust, note the feeding marks -

Most of Savernake's sallows are in poor condition for larvae, with Willow Rust, Sallow Mildew and Tar Spot. Worse, everywhere, sallows came into leaf unusually early, following the mild winter; this means that the leaves were unsuitably thick and coarse by the time first instar larvae were feeding. It may be that a lot of L1 larvae failed, but we wont know as most egg case bases got washed out by heavy rains. 

One again, iris has got to outmanoeuvre a lot of problems if it is to fly in numbers next summer; but don't underestimate him - for a start, it's likely that tit predation of hibernating larvae will be relatively low this coming winter.  

Here's what one of my favourite sallows in Savernake looked like on Saturday, with white mildew on a lower bough, sparse and thick-leaved foliage and a lot of Willow Rust (plus squirrel damage, back right).  We didn't find anything on it -

And here's what a healthy, suitable sallow should look like in Sept - 

complete with damsel not in distress...

 

Early Autumn Larvae: Not Good News...

My first post for a while... (I've been hors de combat). 

Incredibly, it seems that I topped and tailed the 2024 flight season: I know of no adult records subsequent to mine on Aug 11th, nationally...  

It looks as though larvae are in low or very low numbers this early autumn, though I'm only just getting into the swing of looking for them. I've had a big session in Savernake, and have looked in Cirencester Park Woods and at Lambourn (the latter two sites only support very small populations).  

Bad news: None so far at Cirencester and Lambourn, and a big session yesterday in Savernake (3 searchers, totalling 14 hours of actual foliage searching) produced only one mid-2nd instar larva and a 1st instar fail + egg case base. Here's the one we found, showing distinctive feeding marks on a classic midgreen soft matt leaf - 

One major breeding area in Sav drew a total blank, suggesting that Herself hadn't wandered there. 

The main problem at all three of my study sites is finding suitable foliage: sallows in exposed or open situations are heavily infested by Melampsora Willow Rust, and / or are too thick-leaved (because the sallows came into leaf ridiculously early), and many overhung sallows are heavily coated in Sallow Mildew (which proliferates in wet autumns). 

Sallow foliage quality is, fortunately, quite high in shady situations. So there is Hope... 

Here's a Tree Damsel Bug Himacerus apterus, found on sallow in Sav yesterday. This is a serial killer of caterpillars and persona non grata on sallows (I translocated it onto a birch tree, and told it to Go and Sin No More)... 

   

Sun Aug 11th: Last Post in Savernake

Checked the best territories in south Savernake today. Just this one male, in reasonable condition, in the Dead Beech Glade for 40 mins either side of 3 O'clock. Then, realising he was all alone at the party, with not even a bumblebee to chase, he drifted off and away... 

Sat Aug 10th -Still Flying in Glos!!!

The most worn and faded Emperor I've ever seen was smashing things up this afternoon at Sapperton, W of Cirencester, Glos - a faded pinky-yellow in colour, rather like a very worn migrant Painted Lady. The wind prevented me from photographing him.  At one point he eviscerated a high-flying Large White.   

Aug 8th - female in Norfolk & another Derbys Sighting

 Drizzle leading to heavy rain in Glos today, which could end the PE season there - we'll find out tomorrow...

Meanwhile, a female was photoed near Cromer in Norfolk today, and a second Derbyshire sighting has come to light - a female feeding on a trackway on July 18th near Aston on Trent, SE of Derby.

Wed Aug 7th: Apatura iris versus a bat...

Today is my birthday, and also that of Emma Grundy in Radio 4's The Archers. I am seven. I set off somewhat speculatively for Savernake in indifferent weather, but arrived there in sunshine and managed to see two Emperors smashing things up before the sun went, and Stygian gloom descended, and deepened.

It got so dull that at 3pm a bat started batting about, a Noctule I think, high up in the best of the known Savernake territories, the Dead Beech Glade. Of course, a hidden Emperor went for it - I had no idea that there was a male there.

I don't know of any other records of Apatura iris pursuing a bat, but all things are possible with this the best of all possible butterflies...

This may well be an excellent way for the 2024 season to finish, though I suspect there's a few days left at Savernake. 

Emperors have the habit of doing something particularly ridiculous at precisely 3pm (at Knepp you can set your clock by it). This habit has given rise to the term, 'the 3 O'clock Emperor'...