Red Admiral overwintering 2018/2019

[Paul Harfield]

Red Admiral Update
The one remaining Red Admiral that had been roosting in my garden, amongst plastic foliage in a hanging planter, has now gone. I was just thinking about setting up some sort of movement activated camera to monitor what was going on, but I was too late .
I noticed this on 27th January. The days leading up to this had been mildish during the day and I had noticed some slight changes in its position. I am sure it has survived and flown elsewhere.
So for anybody interested here is a recap:
This butterfly appeared in my garden on 27th October 2018. On 20th November I noticed there was now 2 Red Admirals. This second Red Admiral disappeared between 21st-23rd December (1 month approx. 33 days). The original Red Admiral disappeared around 26th/27th January 2019 (3 months approx. 92 days).

[Chris Jackson]

Good report Paul.

Hi Folks,
I am continuing my Red Admiral caterpillar report from the end of last year.
Close to my workplace in Vitrolles, France, in the Bouches du Rhone département, I am keeping an eye on a small south-facing bank that attracts Red Admirals.
Nettles are not all that common in my otherwise arid area. Parietaria officinalis is the more common host plant it seems.
Despite a 'strimmer' masacre by council workers at the start of December last year, there are still some nettles here with V. atalanta cat. winter tents on them.
This is a reminder of the site in my local park. The remaining nettles are at the foot of these trees.

It is quite easy to identify the caterpillar tents:

and here:

and here with a precariously damaged stalk:

I opened up the damaged tent here-above as the cat. will no doubt be obliged to 'move house' in the coming days.
Here he is, 7 mm long and healthy looking:

Placed on a darker background for a photo.

Just at the foot of this row of trees, the council 'strimming' programme probably killed off 100s of potential 2019 RA imagos.
Can someone confirm the larval stage ?
2nd ?
Thanks
Chris

[David M]

Great observations, Chris, especially when the Council has done its best to eradicate everything!

[Vince Massimo]

Hi Chris,

The size and appearance of your larvae indicate that they are all early 3rd instar.
There is also a possibility that the damaged stem may be the result of larval activity. Later instars will topple the top of a plant and form a tent in the upper leaves, as in this example.

If you can relocate the plant, it would be worth checking the group of leaves at the apex to see if there was a tent there.

Vince

[Vince Massimo]

A trip to Lancing on the Sussex coast over the weekend gave me the opportunity of checking for Red Admiral larval tents where I had previously seen eggs being laid. The nettles growing in the shelter of a couple of south-facing walls near the seafront produced 10 typical tents of various shapes and sizes. A couple were gently investigated and contained 3rd instars.

Red Admiral larval tent - Lancing, Sussex 17-Feb-2019

Red Admiral larval tent (context) - Lancing, Sussex 17-Feb-2019

Red Admiral larval tents - Lancing, Sussex 17-Feb-2019

Red Admiral larval tent - Lancing, Sussex 17-Feb-2019

Red Admiral larval tent - Lancing, Sussex 17-Feb-2019

Additionally there were 2 larvae found out in the open in the sunny conditions, One was a 2nd instar which was feeding outside of another tent and a newly moulted 4th instar looking for a new leaf.

Red Admiral 2nd instar plus tent - Lancing, Sussex 17-Feb-2019

Red Admiral 4th instar - Lancing, Sussex 17-Feb-2019

However not all shelters contained Red Admiral larvae and some moth larvae were also seen. If the larva had not been visible in this case, the existence of long silk guy-lines outside of the tent would indicate that it was constructed by a moth. I have found that Red Admiral larvae do not do this unless they are forming a pupation tent which is a very different form of structure.

Moth larva - Lancing, Sussex 17-Feb-2019

Vince

[David M]

Fabulous, Vince. Those nettles are coming along nicely (as are the RA larvae)!

[Vince Massimo]

I visited Ferring Rife on the Sussex coast on Sunday 24th February, primarily looking for Small Tortoiseshells, but was surprised to find a very fresh Red Admiral laying eggs.

Ferring Rife, Sussex 24-Feb-2019

These were on a very scruffy plant growing against a west-facing fence.

Red Admiral eggs - Ferring Rife, Sussex 24-Feb-2019

I intend to rear these through to see how their development rates compare with November and December eggs.

Neil Hulme also reported egglaying in Sussex on 22nd and 24th February and David Cook on 26th.

Vince

[millerd]

Red Admiral seen laying next to the River Colne at Stanwell Moor (Near Heathrow) today.

Dave

[Vince Massimo]

I have been receiving reports from Dave Harris of Newhaven, Sussex who has been monitoring overwintering Red Admiral larvae in his garden. He advises that the first of these pupated on 26th February, a second on 18th March and third on 26th March. The first one emerged as an adult on 29th March and the second on 14th April (both after approximately 4 weeks). Two others emerged on 20th and 21st April, each after approximately 3 weeks in the pupal stage.

Vince

[Chris Jackson]

04 March 2019
An update on the French Red Admiral caterpillars.
Since my last posting on 07 February, my RA cat (and I think that it is the same individual), has doubled in size and is now 14 mm long.
Is this 4th instar ?

A reminder of the context:

Chris

[Vince Massimo]

Hi Chris, your larva looks like late 4th instar.

Vince

[Chris Jackson]

Hi Folks - 14th of March 2019

Update on Red Admiral early stages from the south of France.

After confirmation with Vince, this is a freshly moulted 5th instar caterpillar. It is 18 mm long.

Here is the same 5th instar cat. at the top of this photo, whereas the darker cat. below is late 4th instar and is 16 mm long.

Again, 5th instar on the left and 4th instar on the right.

Context view. Fortunately the council has refrained from strimming the nettles under the trees for the moment.

Chris

[Vince Massimo]

Thanks Chris, that's all useful data. It's interesting to see that your larvae seem to be developing at the same rate as those in the UK despite being in the south of France.

For several years I have been wondering how Red Admirals can lay eggs in January and February and have been investigating three possible scenarios.

1. Overwintering females manage to keep a supply of fertilised eggs (or a store of sperm) throughout the winter.
2. Newly-emerged females mate in winter (can be either home-grown or migrants).
3. Neither of the first two options is true and any eggs laid in January and February are infertile.

Now, having observed a female laying two eggs on 24th February at Ferring Rife on the Sussex coast, I can discount option No.3.

I collected the two eggs and have had them under observation. One hatched on 14th March and the other on 15th (after developing for 18-19 days).

Red Admiral egg (nearing hatch) - Crawley, Sussex 11-March-2019

Red Admiral larva (L1) - Crawley, Sussex 15-March-2019

Red Admiral larva (L2) - Crawley, Sussex 15-March-2019

The butterfly that laid the eggs looked very fresh, so probably fell within option 2 and mated in winter. (Other species that hibernate do not mate until after coming out of hibernation in the spring). It is not possible to be sure whether she emerged locally or was a migrant from the continent. At the time of the sighting at this south coast location there had been a run of southerly winds for several days and record winter temperatures were building.

More study is needed in order to understand what happens to this species outside of the traditional southern European winter breeding grounds.

Vince

[Vince Massimo]

Over the weekend of 23rd/24th March I searched the nettle beds on the seafront at Lancing and found the tents of 16 Red Admiral larvae that have overwintered there. Only two were gently investigated and they contained 4th and 5th instar larvae.

Red Admiral larval tent (5th instar) - Lancing, Sussex 23-Mar-2019

Red Admiral larval tent (4th instar) - Lancing, Sussex 23-Mar-2019

Larval tent of unknown moth - Lancing, Sussex 23-Mar-2019

There were also two larvae out in the open and a few moth larval shelters.

Red Admiral larva (4th instar) - Lancing, Sussex 23-Mar-2019

Red Admiral larva (5th instar) - Lancing, Sussex 24-Mar-2019

Vince

[Vince Massimo]

A final update on the winter season.

Firstly, regarding the larval tents I was monitoring at Lancing on the Sussex coast. Some were lost to strimming at the end of March and I lost track of all the remaining ones shortly afterwards (they just disappeared).

Of the two eggs laid just along the coast at Ferring Rife on 24th February, their story unfolded as follows:

Egg laid 24-Feb-2019
Egg hatched on 14-Mar-2019 (after 18 days)
First instar for 11 days (moult to 2nd on 25-Mar-2019)
Second instar for 7 days (moult to 3rd on 1-Apr-2019)
Third instar for 8 days (moult to 4th on 9-Apr-2019)
Fourth instar for 9 days (moult to 5th on 18-Apr-2019)
Fifth instar for 8 days
Pupated on 26-April-2019
Emerged on 17-May-2019 (after 21 days)
Total of 64 days from egg hatch to adult

First instar 15-March-2019

Second instar 27-March-2019

Third instar 4-April-2019

Fourth instar 14-April-2019

Fifth instar 22-April-2019

Pupation tent 1-May-2019

Pupa 14-May-2019

Egg No.2 followed the same pattern, but was a day behind.

Interestingly, the date of these emergences corresponds very well with those resulting from eggs hatching in November and early December.

Another fascinating end to the winter season and many thanks to all those that contributed their observations.

Vince

[David M]

Fascinating stuff, Vince. You've clearly put a lot of effort into that.