Wednesday, April 17, 2024

Early Season Warning!

I know this sounds silly, after such a miserably wet winter and early spring, but the Purple Emperor is likely to be on the wing ridiculously early this year, quite possibly at the end of May...

Larvae came out of hibernation and commenced feeding unusually early, having suffered only relatively low predation rates.

Fourth instar larvae were recorded in Sussex in early April. That's unprecedented. Fourth instar was recorded in Notts, at the northern end of the known Empire, in mid-April.  

Purple Emperor larvae can shoot through the 4th instar, when the weather's dry - and a big anticyclone is (at last) setting in...

Of course, cold and/or wet weather can slow 5th instar larvae right down, but if the May weather behaves, expect this butterfly to be flying by its end, or at the very start of June.

Watch this space!


Tuesday, April 2, 2024

And They're Off!

Purple Emperor larvae have begun feeding unprecedentedly early.  Some in West Sussex were probably feeding in mid-March, and certainly during the three days of balmy weather around the Spring Equinox.

Some larvae were also feeding before the end of March in Oxfordshire and Wiltshire, and probably in Nottinghamshire too.  

These first meals were through 'bud biting' - eating the tip of a loosening leaf bud, usually the terminal bud. This is a new phenomenon, something PE larvae have only started doing these last five years or so - seemingly in response to sallows leafing earlier at the back end of mild winters.  

Here's 'Jadis Queen of Charn', photoed near Lambourn, Oxon, on April 1st. The bud tip has clearly been bitten - 

and here's a well-bitten leaf bud, photoed in Savernake Forest, Wilts, on March 25th -

This suggests that 2024 could see an unusually early PE season, but only if it stops raining (larvae can get stuck for ages skin changing and, especially, pupating in wet weather)...

The other big news is that Winter Bird Predation Rates were Unusually Low, despite high populations of Great Tit and Blue Tit, the assumed main avian predators. We don't have the final figures yet, but it looks as though losses were only in the region of 50% - and some of those were to other causes, this larva here had probably been sucked by a predatory invertebrate -

Fingers crossed, but 2024 could see a good or even very good PE season, weather permitting. Watch this space...  

Finally, here's a classic PE breeding ground: an East to West ride in the northern part of Sherwood Forest, Notts, photoed on March 19th.  Tall but thinned pines to the south and west provide shade from intense sun and shelter from the wind (for egg-laying females), and most of the sallows are young, just starting to flower fully - 


Tuesday, February 20, 2024

Greening Up...

Iris larvae are greening up, already. Most of the 11 larvae I checked in Savernake yesterday were between 20% and 30% green, two were more like 50%. Here's three of them - 

Normally, they're that green in mid to late March, so they are running about four weeks early - for now.

The forest sallows are less advanced, though many roadside sallows around Swindon and the Cotswold Water Park are well in bloom, males and the later-flowering females. One sallow along the A419 at Kingsdown (which is Purple) on the east edge of Swindon is quite well in leaf - any larvae on it might well be feeding.  

One of these years iris will be on the wing in Brexit Britain before the end of May...

Winter predation levels remain within the 'normal' range.

Sunday, February 4, 2024

2023-24 Winter News...

Purple Emperor larvae are about halfway through their five month hibernation. Most hibernate by buds or in forks.

A few hibernate in scars or on lichenised branches - 

They are quite heavily predated during this period, and this winter seems to be no exception. Great Tit seems to be the main culprit. Certainly, when tit numbers are high, Emperor larvae get clobbered. Heaviest losses occur during the late winter period. So we are just entering the main danger time...

Tit numbers are currently very high (even RSPB Big Garden Birdwatch data suggests this...), despite poor weather during the breeding season last year. Blue and Great Tits are everywhere in the woods, though as yet they are not roaming around in sizeable flocks.

Larval losses seem to be following the normal pattern - I lost two in a week in Savernake at the end of January, to assumed bird predation. All that remains is the vacated silk pad, like this -

In addition, I seem to have lost two to invertebrate predation - some sucking bug, that pierces the larval skin and sucks out the contents. Like this - 

This seems to be a phenomenon of modern mild winters...

Whatever, some larvae will survive and thrive, and we will have a Purple Emperor season during 2024. 

This is my 60th year of butterflying, the Purple Emperor entered my life back in June 1964...  So it's party time...

Also, and more importantly, Notes and Views of the Purple Emperor was published sixty years ago, in 1964.  Here's a photo of the lead author, IRP Heslop, with his 37' 'high net', and his van.