Red Admiral overwintering 2017-2018

[peterc]

Went to Knebworth Park earlier. I didn't find the yellow-green eggs which were there last Tuesday - hard to tell whether they hatched successfully or not as I didn't see any obvious signs of a nettle 'tent'. However, I found another RA egg on another plant which looks like a violet of some kind (perhaps Hairy Violet - note the hairs on the stem and the leaves on the images). Can any botanist out there confirm please? There was just the odd specimen of this plant scattered among the nettles.

ATB

Happy Christmas and a prosperous 2018 everyone.

Peter

[Jack Harrison]

Surely that can't be Mallow. See viewtopic.php?f=8&t=9581&start=20#p127040
If it is, it would neatly square the circle.

Jack

[peterc]

Surely that can't be Mallow. See viewtopic.php?f=8&t=9581&start=20#p127040
If it is, it would neatly square the circle.

Jack

Thanks Jack. I thought it was Mallow at first but after consulting one of my Wild Flower guides it looks more like a violet species to me but I stand to be corrected of course

Peter

[Jack Harrison]

I am NOT an expert. But my ten penn'orth: , violet leaves are small, perhaps 1.5 cms across. Mallow leaves are substantially bigger at 5+ cms. Here on the (almost) frost-free coasts, eg Findhorn, Mallow grows into sizeable bushes some as tall as 1 metre.

Regardless of what species you have found the eggs on, it would seem to be a brilliant discovery and is perhaps a big pointer to Red Admiral's recent change in fortune. As I said in a PM to you, maybe like the Comma which suddenly had great success when it switched from Hop to Nettle as its main foodplant, British Red Admirals are evolving.

This must have something to do with Brexit

Jack

[bugboy]

Surely that can't be Mallow. See viewtopic.php?f=8&t=9581&start=20#p127040
If it is, it would neatly square the circle.

Jack

Thanks Jack. I thought it was Mallow at first but after consulting one of my Wild Flower guides it looks more like a violet species to me but I stand to be corrected of course

Peter

Hi, I think that leaf belongs to Ground Ivy Glechoma hederacea, a member of the Mint family . Most likely a simple case of mistaken identity on the Admirals behalf.

[peterc]

Thanks, Paul. I think you are spot on your suggestion of Ground Ivy. You might well be right too on the possibility of a case of mistaken identity as there is a nettle plant only centimetres away from the ivy, the leaf of which was partially hidden by the nettle leaves if viewed from directly above.

Yesterday I was hoping perhaps to see some butterflies but it wasn't quite warm and sunny enough. However at a new location, Fairlands Valley Park, Stevenage, there is a rather large open nettle bed facing south-east and sheltered from trees and shrubs on the northern and western sides which looks promising. I did see a female Red Admiral loitering on this bed a couple of months ago suggesting probably that she was looking to lay her eggs but regular subsequent visits have not yielded any eggs. Yesterday, at about 3 inches above ground I saw a couple of folded leaves and found at least one Red Admiral larva.

Happy New Year everyone.

ATB

Peter

[Paul Harfield]

Saturday 30.12.2017 - I made a quick visit to my Red Admiral site at Southwick (Hampshire) yesterday. Unfortunately I missed the brief sunshine in the morning. It was about 14 degrees, but by the time I arrived it was dull, wet & gusty and far from ideal for finding small eggs/larvae or taking photos . Annoyingly I also managed to leave my hand lens at home

Not a great photo but there are 9 eggs on this leaf, some hatched and some not.

I think this is a 2nd or young 3rd instar larva plus an egg for good measure.

I took random pictures of likely larval tents etc and nearly every photo taken surprisingly also has eggs in the shot. There are still plenty of 1st/2nd instar larvae and conveniently one of the larvae I had marked previously (now 4th Instar) was out constructing a new shelter.

Larval tent with a couple of eggs in the shot

Conveniently this previously marked 4th instar larva was out demonstrating its construction technique. Look closely and you can see where it has eaten through all the fleshy parts of the leaf where it joins the main stalk. Although I did not hang around for the process to be completed the next stage would have been biting through some of the veins to ease folding of this leaf

[David M]

Amazing how these larvae are still active at the back end of December (given that this is not a naturally occurring year round UK species).

Much as I'd like a severe cold snap, I also acknowledge that such conditions would likely kill off these early stages, so I'm caught in no-man's land.

[Jack Harrison]

DavidM ...given that this [RA] is not a naturally occurring year round UK species...

But isn't this the point? Recent research (as revealed on ukb) shows that RA does indeed over-winter in UK but in an immature stage, not as an adult as many might have thought.

Jack

[David M]

Well, it tries to overwinter, Jack, and is clearly doing so ever more successfully (as are Clouded Yellows). I daresay, however, that a prolonged period of intense cold would see mass casualties. The last cold winter we had (Feb/Mar 2013) seemed to account for most Red Admirals and I personally didn't see any until after midsummer!

[Paul Harfield]

DavidM ...given that this [RA] is not a naturally occurring year round UK species...

But isn't this the point? Recent research (as revealed on ukb) shows that RA does indeed over-winter in UK but in an immature stage, not as an adult as many might have thought.

Jack

As you rightly say there is plenty of evidence for the Red Admiral surviving the Winter in its larval stage over the couple of years. This will hopefully be fully documented in this ongoing thread in different locations. I believe there is also evidence to suggest that the eggs can also survive the best part of the winter (maybe Vince could confirm that).
My own personal experience has shown that the larvae are quite capable of surviving temps down to at least -4 or -6 degrees and for several days when the temp only rises to +2 degrees during the day. This was the case in the winter of 2014/2015 when I recorded a Red Admiral larva taking 76 days to complete its 1st instar in captivity.
I would also say that there is also plenty of evidence to suggest that adult Red Admirals can also survive the winter down here in the extreme south at least, given the right conditions.
What we have not seen for quite a few years is a prolonged period when the temperature remains firmly below freezing. It would be interesting to know what happens to Red Admirals in other countries where the climate varies from that in the UK.

[Vince Massimo]

... I believe there is also evidence to suggest that the eggs can also survive the best part of the winter (maybe Vince could confirm that)...

The most comprehensive data on this subject has been provided by David Harris of Newhaven, Sussex. This from "The Butterflies of Sussex" (Blencowe/Hulme).

"Eggs laid on 2nd December 2014 produced adults in mid May 2015, with the complete life cycle taking a total of about five-and-a-half months...Another batch laid on 2nd November 2015 produced three adults on 1st May 2016, after a full six months...The period spent within each of the development stages will vary in response to temperature, taking as long as two months as an egg, three as a caterpillar and one as a chrysalis."

I have personally seen the larval stages take 5 months over the winter of 2015/2016 following an egg hatch on 6th November.

I have not yet been able to directly observe an egg through the winter, but should have some more data soon.
What I have so far is:

*Eggs laid on 18th September 2107 hatched on 30th October (after 12 days). Larvae at 4th/5th instars on 1-Jan-2018.
*Egg laid on 9th October 2015 hatched on 6th November (after 28 days). Larva at 3rd instar on 1st Jan 2016.
*Eggs found on 17th November 2017 are unhatched (after 46 days so far). Monitoring continues.

A visit to the Cemetery Wall site in Crawley on 1st January 2018 found an estimated 100 eggs still remaining. The majority look healthy and they have been hatching steadily during the latter part of December.

Red Admiral eggs - Crawley, Sussex 30-Dec-2017

Only one larva (4th instar) remains at the Football Stadium site, while my garden larvae continue to develop slowly at 4th and 5th instars.

Vince

[Vince Massimo]

A visit to the Cemetery wall site in Crawley today found a larva emerging from its egg. It looked ready to emerge over a week ago, but things move slowly at this time of year.

Red Admiral egg (showing developed larva inside) - Crawley, Sussex 30-Dec-2017

Red Admiral larva preparing to emerge - Crawley, Sussex 7-Jan-2018

Red Admiral larva emerging - Crawley, Sussex 7-Jan-2018

Red Admiral larva emerging - Crawley, Sussex 7-Jan-2018

Red Admiral larva (newly emerged) - Crawley, Sussex 7-Jan-2018

There are also still scores of unhatched eggs.

Red Admiral eggs - Crawley, Sussex 7-Jan-2018

The temperature today was 6C in sunny conditions, but with a cold wind.

At the other end of the larval life cycle, two of the 5th instars in my garden are preparing to pupate.

Red Admiral larva preparing to pupate - Crawley, Sussex 4-Jan-2018

Vince

[Jack Harrison]

I find this all quite extraordinary especially after the recent cold snap. Excellent research.

Jack

[bugboy]

A first visit to Bookham for the year gave me a chance to check on the single Red Admiral egg I found 34 days ago. Although the nettle it is laid upon has been somewhat withered by frost in the intervening days, it still looks to be viable.

On a neighboring leaf I was surprised to find three more. Given that I spent a good 10 minutes searching for eggs on my previous visit I can be reasonably confident in saying they have been laid since the 9th December. They too, on the face of it, look to be viable.

A context shot showing the positions of all four eggs in the nettle, I'll let you guys find them (they're actually quite obvious)

[Vince Massimo]

Thanks Jack. Things like this help to keep me busy during the winter months.

An update from Crawley.
The Cemetery Wall site still has some healthy un-hatched eggs and some of those under observation are now at least 60 days old.

Red Admiral eggs - Crawley, Sussex 19-Jan-2018

They have been hatching steadily through November, December and January and it would not surprise me to see some of them hatching in February.

A few days ago I visited and found three 1st instar larvae visible in the crown of one of the plants. However, one of them was clearly dead.

Red Admiral larvae (1st instars) - Crawley, Sussex 17-Jan-2018

My garden larvae continue to develop very slowly, but unfortunately the two 5th instars that were preparing to pupate failed to survive the transition.

Vince

[essexbuzzard]

If those eggs survive, at this stage, for another month, then we can say the Red Admiral can overwinter at the egg stage as well, which would be fascinating!

[Vince Massimo]

If those eggs survive, at this stage, for another month, then we can say the Red Admiral can overwinter at the egg stage as well, which would be fascinating!

Watch this space, Mark

Back to the Cemetery Wall site in Crawley for an egg count today, however, before I could start, a Red Admiral flew across my path at 12.20 but did not stop. At the time it was slightly cloudy with a temperature of 9C.
A full count along the whole length of the wall produced 20* unhatched Red Admiral eggs, 3 of which were nearing emergence.

Red Admiral egg (nearing emergence) - Crawley, Sussex 25-Jan-2018

They were all photographed and their positions marked in order to keep track of them and hopefully record when the last one hatches.

Red Admiral egg - Crawley, Sussex 25-Jan-2018

There was also lots of other activity at the base of the wall, including snails, spiders, beetles, weevils, a small parasitic wasp and many tiny 16-Spot Ladybirds.

Red Admiral egg and 16-Spot Ladybird - Crawley, Sussex 25-Jan-2018

Vince

*EDIT: A more concentrated effort on 27th January found 5 more eggs, making a total of 25.

[David M]

With this spell of mild weather lately, I suspect you could see a few successful emergees here, Vince. There doesn't look to be anything amiss weatherwise for the next week so please keep us updated as your observations are most interesting.

[Jack Harrison]

Researchers.

I hope you realise that Moses Harris, Frohawk, South, Ford et al will now be turning in their graves at the way you have challenged the received wisdom.

However, maybe the Red Admiral has evolved and nowadays has adapted to be able to overwinter at various stages of its life cycle. If that is the case, Charles Darwin will be leaping out of his grave with a big grin on his face

Jack