Red Admiral overwintering 2017-2018

[Vince Massimo]

My own personal observations have been curtailed since the Beast from the East, where the foodplant has really taken a battering and I wonder if this is limiting factor in the wild (i.e. a lack of nearby foodplant), rather that the ability of larvae to survive. Thoughts welcome.

In my own experience I am finding that there is still lots of fresh, lush nettle growth on sheltered sites which was unaffected by the recent cold spell. Certainly on more exposed sites it's a completely different story, but I don't think that the butterflies would have laid eggs there in the first place. Ultimately, temperature is bound to be a determining factor in the supply of nettle and the survival rates of eggs and larvae. The effects of this would be more noticeable as you move further north in the country, but there are likely to be a combination of factors involved. In southern and coastal areas it looks like the larvae are tough enough to survive extended periods of cold weather, particularly the early instars which can move to the base of the plant and hunker down between the tightly packed new growth. I have found that the later instars (4th and 5th) have a harder time in the cold weather. Of the many eggs laid in mid-September 2017, which hatched around 30th September, only one sluggish 5th instar survives, despite having a ready supply of food plant. The eggs are also tough, but I don't believe that they can survive to such low temperatures as the larvae. The other limiting factors for eggs appear to be predation and the fact that after a period of time the leaves on which they are laid will shrivel over the winter and drop to the ground making them more vulnerable to loss. I do not have enough data to comment on likely survival rates of pupae and it's really going to take a proper scientific study to draw all of these strands together.

Today the penultimate captive egg hatched here in Crawley. This particular one was laid at the Cemetery Wall site on 21st November 2017, which makes it 110 days old. The larva had chewed part of the top of the egg away during yesterday afternoon, and when I checked it again at 10.40 this morning, it was half way out of its egg.

Red Admiral egg (partially open) - Crawley, Sussex 10-March-2018

Red Admiral larva emerging - Crawley, Sussex 11-March-2018

One egg remains.

Vince

[Paul Harfield]

Have to say that I'm gobsmacked at many of the observations being made here ... this really is rewriting the books! My own personal observations have been curtailed since the Beast from the East, where the foodplant has really taken a battering and I wonder if this is limiting factor in the wild (i.e. a lack of nearby foodplant), rather that the ability of larvae to survive. Thoughts welcome.

Cheers,

Pete

My observations are much are in line with Vinces. There is plenty of lush new Nettle Growth at my site that has been unaffected by the recent frosts and snow covering. I visited today 11.3.2018 which is 2 weeks since my last visit and was surprised that the surrounding vegetation has also seen a burst of growth since then.

Typical condition of Nettle growth at my site. This plant supporting 3x larvae currently - Southwick 11.3.2018

As Vince has also noted the larger larvae observed earlier in the winter seemed to disappear without trace. The smaller larvae seeming more resilient. I think that my site is perhaps more advanced than Vinces as the last of the older eggs was seen 11.2.2018. There has since been new egglaying taking place, but I noticed today all the more recently laid eggs seemed to have also disappeared (I was unable to determine if they had hatched). All the larvae found today were either late 2nd instar or early 3rd instar with a few 1st instar ones still evident.

Most larvae found currently at my Southwick site are in the 2nd/3rd instar stage. 2nd instar premoult above and newly moulted 3rd Instar below both on the same plant - Southwick 11.3.2018

[PhilBJohnson]

Thank you for your updates.
Matthew Oates wrote in The Times newspaper last week saying something like the Red Admiral (I think he was referring to the adult butterfly) needed 10C (approximately) to function.

I say ‘it is England’s Coolest Butterfly’
(In terms of temperature needed for flight)

[David M]

Thank you for your updates.
Matthew Oates wrote in The Times newspaper last week saying something like the Red Admiral (I think he was referring to the adult butterfly) needed 10C (approximately) to function.

I say ‘it is England’s Coolest Butterfly’
(In terms of temperature needed for flight)

I think Small Tortoiseshells might have a claim on that, Phil. I've seen them active in temperatures of just 6c (so long as it's sunny with light winds). Torties are 'open country' butterflies and are usually the first species to be reliably encountered in early spring.

[Paul Harfield]

It has been a while since I have posted about my Red Admiral site. I think there is now light at the end of the tunnel for those larvae that have survived the winter.

18.3.2018 - I was able to locate 1x larva during the snow. The larval tent just visible in the centre of this shot. I did not want to disturb it but it looked like it was 3rd instar. Below a wider view of this Nettle plant.

Out of curiosity, I visited my site at Southwick (Hampshire) during the most recent snow 18.3.2018 . At this visit I was able to locate 1x previously seen larva. I visited again on Sunday 8.4.2018 in the rain. At that visit I was able to locate half a dozen larvae of which half had been seen previously. Development had moved forward significantly for these larvae.

8.4.2018 - The same Nettle clump and larva 3 weeks on. The larva now in its 5th instar shown below is located in the jumble of leaves at the centre of this shot.

8.4.2018 - Having exposed this larva, I was pleased to note as I left that a new shelter was being constructed

The remaining, newly seen larvae were I suspect from eggs laid this year. All of the surviving larvae seen previously are very close to the base of the wall. These newly found larvae are out away from the wall where there was much less healthy Nettle earlier in the year.

8.4.2018 - Two 3rd Instar larvae on this nettle plant plus an empty shelter. One of the larvae shown below

8.4.2018 - One of the newly found larvae which I think likely to be from an egg laid this year.

[peterc]

Your good shots of the Red Admiral larvae and tents prompted me to check on the nettles on my local patch too (Fairlands Valley Park), Paul

There could be light at the end of the tunnel for me as well as these photos show although I am unsure if they provide conclusive evidence that the shelter or tent is harbouring any RA larvae. There appears to be some frass which perhaps is a clue.

ATB

Peter

[Vince Massimo]

There could be light at the end of the tunnel for me as well as these photos show although I am unsure if they provide conclusive evidence that the shelter or tent is harbouring any RA larvae. There appears to be some frass which perhaps is a clue.

I think that looks good for a Red Admiral tent, Peter.

An update from Crawley.

The final egg failed to hatch and was declared dead in mid March.
Of the 5 larvae that hatched from captive eggs on 11th and 18th February, and 5th, 8th and 11th March, four went missing in their first instar and the last one died when it failed to complete a moult to the second instar. These eggs were all laid in November 2017 and came through the winter.

Red Admiral larva 1st instar (preparing to moult) 17-April-2018

Red Admiral larva (failed to moult to 2nd instar) 17-April-2018

Of the many larvae that were being monitored from eggs laid in the 3rd week of September 2017, only one survived to pupate and will hopefully complete its development.

Red Admiral larva (5th instar) 17th-March-2018

Red Admiral pupa (pupated on 27th-March-2018)

At the Cemetery Wall site there has been a lot of new growth and I could only locate 3 larval tents today containing 4th or 5th instar larvae. This does not seem a lot, considering that egg count here last November was over 450.

Crawley, Sussex 18th-April-2018

Red Admiral larval tent - Crawley, Sussex 18-April-2018

Vince

[peterc]

Thanks Vince for confirmation

However when I looked for it again on Tuesday the tent was no longer there. If indeed there was a larva present, it might have moved on after having a good feed over the fine and warm weekend. Or if I am lucky it might have pupated

All the best

Peter

[Vince Massimo]

A visit to Lancing (Sussex) seafront today produced 3 Red Admiral tents. They were in the same location where I found eggs in October 2016 and larvae in March 2017, which is on nettles in the shelter of south and west facing walls near the main car park. All the tents were fairly modest structures which contained 4th or 5th instar larvae, some of which were visibly active.

Tent 1 (west-facing) - Lancing, Sussex 19-April-2018

Tent 2 (south-facing) - Lancing, Sussex 19-April-2018

Tent 3 (south-facing) - Lancing, Sussex 19-April-2018

Vince

[Vince Massimo]

A final update from Crawley.

The final remaining larva that I was monitoring which pupated on 27th March 2018 produced an adult butterfly on 22nd April. It looked undersized, but flew away strongly when released. This was the only survivor of 20 that I was closely watching.

Red Admiral pupa 22-April-2018

Red Admiral (ready for release) 22-April-2018

Its development took the following course:

Egg laid 18-Sept-2017
30-Sept-2017 egg hatched to produce 1st instar (after 12 days)
13-Oct-2017 moulted to 2nd instar (after 13 days as 1st instar)
18-Oct-2017 moulted to 3rd instar (after 5 days as 2nd instar)
1-Nov-2017 moulted to 4th instar (after 14 days as 3rd instar)
30-Dec-2017 moulted to 5th instar (after 60 days as 4th instar)
27-Mar-2018 pupated (after 87 days as 5th instar)
22-Apr-2018 emerged as an adult (after 26 days as a pupa)
Overall its development took 216 days (7 months) from the date the egg was laid. 2 months of that was spent as a 4th instar and 3 months as a 5th instar. The dates for the 1st, 2nd and 3rd instars are the averages of 6 larvae that came from the same batch of eggs, but developed at slightly different rates.

The results from the cemetary wall site in Crawley were disappointing. After counting over 450 eggs there in November 2017, only 3 larval tents were found on 18th April 2018 and these had disappeared by 21st April, so no confirmed survivors.

A summary of the many observations received from UKB members from around the country tells an interesting story.

Eggs were observed being laid in September, October, November, December (possibly) and February. Reports came in mainly from southern counties, but some from as far north as Lincolnshire. Large concentrations of eggs were reported from Sussex and Hampshire in November 2017.

Larvae were recorded as hatching in September, October, November, December, January, February and March and were seen to be active through those months.

Some eggs which were laid in mid November 2017 hatched in February 2018 (in the wild) and March 2018 (in captivity) which is 90 to 110 days.

The longest period recorded for a pupa was 26 days.

Vince

[Paul Harfield]

Following on from Vinces final update. I though I should give an update from my most recent visits to my site at Southwick (Hampshire).
21.4.2018 - At this visit I was only able to locate a couple of 3rd instar Red Admiral larvae. No sign of the other larvae from previous visits. I tend to think that these 3rd instar larvae were from eggs laid in February rather than from any laid last year.
6.5.2018 - At this visit made during good butterfly weather I was hoping I might see a newly emerged Red Admiral. In fact I was unable to find any evidence of any stage of Red Admiral. The vegetation had grown on unbelievably and it is possible there may have been a larval tent tucked away but I could not find any. I am still hopeful that a fresh Red Admiral may still emerge. I will continue to monitor this site for them for the next couple of weeks.

[peterc]

Following on from Vince's and Paul's updates I can reveal what occurred on my sites in the Stevenage area: Knebworth Park and Fairlands Valley Park.

Despite frequent visits to these sites in the last two or three months I have not see any adult Red Admirals. There is a report of a sighting in the area this year, at Shephall, perhaps a mile away, but a tatty specimen on 18 February. It therefore appears unlikely that any of the eggs and larvae that I found over the winter have survived to adulthood. I suspect the first adults we see from now on will be migrants.

ATB

Peter

PS I updated post on 18 May to include report of a sighting earlier in the year which I previously missed

[Paul Harfield]

A final instalment from my Southwick (Hampshire) site. A brief visit yesterday 27.5.2018 produced a single adult Red Admiral. I disturbed this individual after which it settled briefly wings closed. Unfortunately I did not get the opportunity for a close look or photo before it disappeared over the trees, but it looked in reasonably fresh condition. Of course I have no idea if this individual is a new arrival, the product of eggs laid last year or the product of eggs laid in February. I suspect the latter scenario, but I would appreciate feedback from Vince on this.

[Vince Massimo]

I revisited the cemetary wall site in Crawley on 27th May and found 6 late-instar larval tents, but they were all empty. However I then discovered a 5th instar larva out in the open on the edge of the nettlebed.

Red Admiral 5th instar larva - Crawley, Sussex 27-May-2018

It was in the same area where eggs were hatching in January, so it could be a survivor. I moved it deeper into the nettles and it quickly constructed a new tent.

Red Admiral 5th instar larval tent - Crawley, Sussex 27-May-2018

As regards Paul's question, I can only speculate. I know from experience that adults emerging from late April to the 3rd week of May usually come from eggs which hatched the previous November. However these adults are now mingling with migrants, so the picture can be confusing. Based on my recent larval sighting, my gut feeling is that it came from an egg which hatched in January and at the present rate of development will emerge as an adult in mid to late June. Part of the reasoning for this is that I checked for fresh eggs in February and March, finding none.

Vince