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'...