Red Admiral (Early Stages)

[Vince Massimo]

The Red Admiral is primarily a migrant to our shores, although sightings of individuals and immature stages in the first few months of the year, especially in the south of England, mean that this butterfly is now considered resident. This resident population is considered to be only a small fraction of the population seen in the British Isles, which gets topped up every year with migrants arriving in May and June that originate in central and southern Europe. This particular species is often observed flying into a headwind on its in-bound and out-bound migrations. The butterfly is not able to hibernate in the strictest sense of the word and the majority of adults leave the UK in late August to mid-October without mating and fly south to the winter breeding grounds in southern Europe. Those that remain are usually unable to withstand our winter, especially in the cooler regions of the British Isles, however there have been increasing records of small numbers of adults overwintering during mild winters. Regular records also exist of late eggs and larvae which develop slowly in very sheltered locations, usually on or near the south coast, and produce spring adults. As will be described later, it has now been established that eggs can be laid throughout the winter and larvae can hatch in any month of the year. Because it does not hibernate, the butterfly can become active on any sufficiently warm day in winter, so can be seen in any month of the year. When surveying for overwintering butterflies during the winter of 2014/2015 I recorded and photographed a specific individual butterfly on 6th December 2014 and again, 64 days later on 8th February 2015.

Christmas Red Admiral - Crawley, Sussex 25-Dec-2015

Winter Red Admirals - Crawley, Sussex 20-Feb-2017

10 winter Red Admirals - Crawley, Sussex 16-Feb-2024

The Ovum and Larva

Red Admiral eggs are laid singly on the upperside of the leaf of the host plant, usually Common Nettle (Urtica dioica). They are similar in appearance to those of the Comma, but in my experience they are laid towards the middle of the leaf, whilst the Comma tends to prefer the leaf edges. However this is not always the case and there are inevitable exceptions

Red Admiral ova - Crawley, Sussex 9-Dec-2017

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

Red Admiral ovum - Crawley, Sussex 23-Oct-2015

Ovum (6 days before hatching) - Crawley, Sussex 31-Oct-2015

Ovum (3 days before hatching) - Crawley, Sussex 3-Nov-2015

Ovum (1 day before hatching) - Crawley, Sussex 5-Nov-2015

Red Admiral ovum preparing to hatch - Crawley, Sussex 30-Jan-2018

Red Admiral ovum preparing to hatch - Crawley, Sussex 30-Dec-2017

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

Red Admiral 1st instar larva - Crawley, Sussex 7-Jan-2018

After hatching, the larva initially forms a silken tent on the underdside or upperside of a tender leaf, or within the terminal leaves of the plant. As it feeds and grows the shelters become more elaborate. In November 2015 I observed a larva progressing through a series of shelters, all of which were different. This may not be typical behaviour in this case because the larva in question was the result of a late egg and its development could have been affected by the colder weather.

Red Admiral 1st instar larva - Crawley, Sussex 7-Mar-2018

1st instar (newly emerged) - Crawley, Sussex 6-Nov-2015

1st Instar (first shelter) - Crawley, Sussex 7-Nov-2015

1st Instar (second shelter) - Crawley, Sussex 8-Nov-2015

1st Instar larva (constructing third shelter) - Crawley, Sussex 9-Nov-2015

1st Instar (third shelter) - Crawley, Sussex 10-Nov-2015

1st Instar (fourth shelter) - Crawley, Sussex 12-Nov-2015

Red Admiral 1st instar larva - Crawley, Sussex 3-Oct-2017

Red Admiral 1st instar larva - Crawley, Sussex 9-Dec-2017

The variability in the colour of the larva starts in the second instar which can be either completely dark or have pale yellow markings, including some yellow-tipped spines.

Red Admiral 2nd instar larva - Crawley, Sussex 1-Aug-2017

Red Admiral 2nd instar larva - Crawley, Sussex 31-Jul-2018

Red Admiral 2nd instar larva - Crawley, Sussex 31-Jul-2018

Red Admiral 2nd instar larva - Crawley, Sussex 10-Dec-2017

Red Admiral 2nd instar larva - Crawley, Sussex 3-Dec-2015

Red Admiral 2nd instar larva - Crawley, Sussex 25-Dec-2016

The third instar is similarly dark or coloured, but all now have a noticeable broken yellow stripe low down along the side and also more complex and branching spines

Red Admiral 3rd instar larva - Crawley, Sussex 12-July-2017

Red Admiral 3rd instar larva - Crawley, Sussex 19-July-2017

Red Admiral 3rd instar larva - Crawley, Sussex 4-Apr-2019

Red Admiral 3rd instar larva - Crawley, Sussex 4-Apr-2019

Red Admiral 3rd instar larva (pre-moult) - Crawley, Sussex 8-Apr-2019

By its third instar it generally proceeds to construct a full tent by folding the edges of a leaf together and binding the sides of the join with silk. The following two images show the progression of a larval tent utilised by an overwintering larva which chose to feed entirely within the structure and moulted inside the remainder. However not all shelters fit this pattern and some may be folded downwards.

3rd instar larval tent (newly formed) - Crawley, Sussex 19-Dec-2015

3rd instar larval tent (after 17 days) - Crawley Sussex 5-Jan-2016

These early shelters are unmistakable because they are usually very symmetrical, unlike the tents formed by some moths and other insects and spiders which also feed or shelter on nettle. The most likely cause for confusion that I have observed is a type of shelter formed by some larvae of the Small Tortoiseshell when they start to disperse from their communal webs. They construct and use these for protection during the few days when they are moulting. However these tend to be found near the old webs and there are often several in a small area. Another common cause of confusion are the tents of the Nettle-tap moth larva which are very common at the same time of year.

I watched a third-instar larva construct a larval tent from scratch. It first lays strands of silk across the top rear edge of the chosen leaf, just forward of the stalk and then chews some holes in the base of the leaf, avoiding the main veins. The silk strands may stop the now weakened leaf from distorting downwards and the two upper edges of the leaf are then gradually knitted together with more silk, leaving a small opening at the tip.

Red Admiral 3rd instar larva constructing tent - Chaldon, Surrey 30-July-2011

Red Admiral 3rd instar larval tent - Chaldon, Surrey 1-August-2011

The above photo is also interesting in that it shows an earlier abandoned effort on the leaf below. The larva laid down the first silken strands but then decided to move to another leaf. The resulting structure is unlike anything else and is reminiscent of a closed Venus fly-trap leaf. The original hole(s) made by the larva at the base of the leaf should still be visible, although it is sometimes obscured by folds in the leaf. This particular feature confirms that the shelter was made by a Red Admiral larva.

Red Admiral 4th instar larval tent - Crawley, Sussex 22-Feb-2016

Red Admiral 4th instar larva (post moult) - Crawley, Sussex 9-Apr-2019

Red Admiral 4th instar larva - Crawley, Sussex 21-Jul-2017

Red Admiral 4th instar larva - Crawley, Sussex 21-July-2017

Red Admiral 4th instar larva - Crawley, Sussex 25-July-2017

Red Admiral 4th instar larva - Crawley, Sussex 6-July-2017

Red Admiral 4th instar larva (pre-moult) - Crawley, Sussex 30-July 2017

The larva emerges from its shelter to feed on adjacent leaves, but also partly consumes its early shelters and constructs larger ones as it grows, usually higher up the same plant. There should therefore be a succession of shelters, with the larva hopefully being found in the largest, if it survives predation. Succeeding shelters will not necessarily be of the folded leaf type and the larva may move to other plants.

Multiple larval tents, Woldingham, Surrey 1-June-2012

Some final tents can be very distinctive structures, usually formed at the top of the plant and comprising a number of leaves knitted together with silk. Part of the process is that the larva chews part-way through the top part of the main stem, which topples but remains attached to the plant. The larva continues to feed in this shelter and may pupate inside if there is sufficient room. If not, it utilises larger leaves further down the plant, which are loosely joined together with silk strands.

Typical Red Admiral 5th instar larval tent, Chaldon, Surrey 22-August-2011

Red Admiral 5th instar larval tent - North Stoke, Sussex 6-April-2017

Red Admiral 5th instar larval tent - North Stoke, Sussex 6-Aril-2017

It has been observed that pupation tents can usually be distinguished from ordinary shelters by having additional supporting external silk strands.

Red Admiral pupation tent - Crawley, Sussex 1-May-2019

Red Admiral larvae have several colour forms, ranging from black through greenish-brown to a very pale yellowish-green. These colours mainly appear in the final instar and usually intensify and change significantly as the larva becomes full grown.

Red Admiral larva (moulting to 5th instar) - Crawley, Sussex 31-July-2017 (L1)

Red Admiral larva (freshly moulted 5th instar) - Crawley, Sussex 31-July-2017 (L1)

Red Admiral larva (early 5th instar) - Crawley, Sussex 1-Aug-2017 (L1)

Red Admiral 5th instar larva - Crawley, Sussex 5-Aug-2017 (L1)

Red Admiral 5th instar larva - Crawley, Sussex 15-July-2017 (L2)

Red Admiral 5th instar larva - Crawley, Sussex 24-Aug-2020 (L3)

Red Admiral 5th instar larva - Lancing, Sussex 28-Mar-2019 (L4)

Red Admiral 5th instar larva - Crawley, Sussex 29-Mar-2023 (L5)

Red Admiral early 5th instar larva - Crawley, Sussex 9-Mar-2016 (L6)

Red Admiral 5th instar larva - Crawley, Sussex 15-Mar-2016 (L6)

Red Admiral late 5th instar larva - Crawley, Sussex 23-Mar-2016 (L6)

Red Admiral 5th instar larva - Crawley, Sussex 17-Mar-2018 (L7)

Red Admiral 5th instar larva - Crawley, Sussex 30-Mar-2017 (L8)

Red Admiral 5th instar larva - Crawley, Sussex 27-May-2018 (L9)

Red Admiral 5th instar larva - Lancing, Sussex 11-Sept-2019 (L10 )

Red Admiral 5th instar larva - Crawley, Sussex 22-Apr-2019 (L11)

Red Admiral 5th instar larva - Crawley, Sussex 6-Apr-2017 (L12)

Red Admiral 5th instar larva - Crawley, Sussex 12-Apr-2017 (L12)

Red Admiral 5th instar larva - Crawley, Sussex 20-Apr-2024 (L13)

Red Admiral 5th instar larva - Crawley, Sussex 22-Apr-2019 (L14 )

Red Admiral 5th instar larva - Lancing, Sussex 6-Sept-2019 (L15 )

Red Admiral 5th instar larva - Crawley, Sussex 26-Mar-2019 (L16)

Red Admiral 5th instar larva - Lancing, Sussex 6-Sept-2019 (L17 )

Red Admiral 5th instar larva - Lancing, Sussex 6-Sept-2019 (L18 )

Red Admiral 5th instar larva - Crawley, Sussex 17-Apr-2017 (L19)

Red Admiral 5th instar larva, Caterham, Surrey 23-June-2011 (L20)

Red Admiral 5th instar larva, Caterham, Surrey 23-June-2011 (L20)

Red Admiral 5th instar larva (parasitised) - Gatwick, Sussex 10-Sept-2018

The Pupa

Pupation follows a recognised sequence, commencing with the larva suspending itself upside down from the underside of a leaf or stalk.

Red Admiral larva preparing for pupation, Caterham, Surrey 29-June-2011

Red Admiral larva just prior to commencement of pupation, Caterham, Surrey 29-June-2011

Red Admiral larva commencing pupation, Caterham, Surrey 29-June-2011

Red Admiral larva completing pupation, Caterham, Surrey 29-June-2011

Fresh Red Admiral pupa, Caterham, Surrey 29-June-2011

Typical Red Admiral pupa, Caterham, Surrey 4-July-2011

Red Admiral pupa (typical ventral view) - Crawley, Sussex 27-Apr-2017

Red Admiral pupa (typical dorsal view) - Crawley, Sussex 30-July-2023

In the above case, the pupal stage lasted 17 days. In the days prior to emergence there were some very subtle colour changes to the pupal case, until suddenly, on the final morning, the whole pupa darkened and the colours of the wings showed strongly through the outer case.

Red Admiral pupa (3 minutes before emergence), Caterham, Surrey 16-July-2011

In 2011 two adults were reared and released. Both were female, one being ab.bialbata, which displayed white spots within the red bands of the forewings.

Red Admiral female ab.bialbata (freshly emerged), Caterham, Surrey 20-July-2011

Red Admiral female (freshly emerged), Caterham, Surrey 20-July-2011

Red Admiral female (freshly emerged), Caterham, Surrey 20-July-2011

Large and small larval tents are easy to spot, so it is worth checking out your local nettle patch, especially on fresh growth in a sunny, sheltered location.

Vince

Reading References:
The Butterflies of Britain and Ireland (Thomas and Lewington 2014)
UK Butterflies Website

[Pete Eeles]

Excellent Vince, just excellent

Cheers,

- Pete

[David M]

Absolutely fascinating. Thank you so much for sharing that.

[Nick Broomer]

thoroughly enjoyed your pictures, excellent

[Lee Hurrell]

Good work, Vince - another informative and eductional report!

Cheers

Lee

[59 SPECIES]

Superb Vince. No other word

[Vince Massimo]

Thanks for the comments everybody and especially to Pete for the proxy tweet .

It made a change to complete a Species Report inside 2 months. It usually takes the best part of a year to put one together because I prefer to only use my own photos.

I have two unfinished projects at the moment which will be completed in 2012 and I also hope to get to grips with some more "Nettle-Eaters" and "Whites" next season.

Cheers,
Vince

[Vince Massimo]

2012 turned out to be a very good year for Red Admiral and the season started very promisingly when I discovered a very early egg-laying female a few hundred metres from home on 20th March. She was responsible for at least 14 eggs (3 of which were on the same nettle leaf).

3 Red Admiral ova - Caterham, Surrey 20-March-2012

Many larval tents could be found throughout the season, including this one which seems to show how the larva progressed across the plant.

Red Admiral larval tents - Woldingham, Surrey 1-June-2012

The tent on the bottom right appears to be the first, with the larva then constructing the second on the bottom left, before progressing to the top left where the first multi-leaved shelter was formed. All tents were vacant, apart from old droppings.

On 20th June I discovered a fully grown Red Admiral larva completely in the open on a nettle plant. This was taken home for further study. It fed for three days and then formed a pupation tent.

Red Admiral pupation tent - Caterham, Surrey 23-June-2012

Pupation took place on 27th June and the adult emerged 12 days later on 9th July.

Red Admiral (reared and released) - Caterham, Surrey 9-July-2012

UKB member Nick Broomer describes in his personal diary of how he monitored a larva in his garden in June 2012. Development times turned out to be slightly longer for the wild individual compared to those which were reared by me, but this is not unexpected.

Summary:

Time spent by larva suspended before pupation:
2011 (reared) - 2 days
2012 (reared) - 2 days
2016 (reared) - 2 days
2012 (wild) - 5 days

Time spent as a pupa, before emerging:
2011 (reared) - 17 days
2012 (reared) - 12 days
2016 (reared) - 13 days
2012 (wild) - 18 days

The 2012 season ended spectacularly with reports from Neil Hulme and Mark Colvin of 1000+ Red Admirals found feeding on the juices of fallen plums at a fruit farm in Ticehurst, East Sussex in mid-September. In 2011 egg-laying was recorded by Richard Roebuck at Goring, East Sussex as late as 15th November and in most years some larvae have been found to be able to over-winter in sheltered spots near the Sussex coast.

Vince

[Vince Massimo]

On 9th October 2015 I observed a Red Admiral laying an egg at a site close to my house in Crawley, Sussex. Knowing that some late eggs can produce larvae which develop slowly over the winter months, I took the egg into care in order to observe its development. The resulting larva, together with its associated plant was given some shelter over the winter and ultimately produced an adult butterfly on 18th April 2016. This was released the following day.

Red Admiral pupa - Crawley, Sussex 18-April-2016

Development took place as follows:

Egg laid 9-Oct-2015
Egg hatched on 6-Nov-2015 (after 28 days)
First instar for 12 days (moult to 2nd on 18-Nov-2015)
Second instar for 29 days (moult to 3rd on 18-Dec-2015)
Third instar for 24 days (moult to 4th on 11-Jan-2016)
Fourth instar for 57 days (moult to 5th on 8-Mar-2016)
Fifth instar for 28 days
Pupated on 5-April-2016
Emerged on 18-April-2016 (after 13 days)
Total of 164 days from egg hatch to adult

UKB member Paul Harfield also documented the development of two larvae over the winter of 2014/2015 in Wiltshire, although neither produced an adult. Notably, one larva went through six instars, but then failed to complete its pupation.
http://www.ukbutterflies.co.uk/phpBB/vi ... 20#p105800
His two larvae developed as follows:

L1 & L2 development overview *(L1 1st & 2nd instar duration is combined)

L1
Ovum 15 days
1st Instar *
2nd Instar 18 days
3rd Instar 14 days
4th Instar 13 days
5th Instar 25 days
6th Instar none
Ovum-Pupa 135 days
Pupa 50 days

L2
Ovum 27 days
1st Instar 76 days
2nd Instar 51 days
3rd Instar 13 days
4th Instar 13 days
5th Instar 13 days
6th Instar 16 days
Ovum-Pupa 209 days

There are also reports from Dave Harris of Newhaven, Sussex which details overwintering eggs and larvae during the winter of 2014/2015.
http://www.ukbutterflies.co.uk/phpBB/vi ... 143#p94263
http://www.ukbutterflies.co.uk/phpBB/vi ... 295#p98371

In 2022 Dave Harris also provided the following data from overwintering larvae in is Newhaven garden.

Larva 1 - Pupated 30th Jan 2022 and emerged on 14th March (after 42 days)
Larva 2 - Pupated 14th Feb 2022 and emerged on 25th March (after 37 days)
Larva 3 - Pupated 9th Mar 2022 and emerged on 8th April (after 30 days)
Larva 4 - Pupated 10th Mar 2022 and emerged on 12th April (after 33 days)
Larva 5 - Pupated 12th Mar 2022 and emerged on 13th April (after 32 days)
Larva 6 - Pupated 21st Mar 2022 and emerged on 16th April (after 26 days)
Larva 7 - Pupated 22nd Apr 2022 and emerged on 10th May (after 18 days)

In 2023 Dave Harris provided further data.

Larva 1 - Pupated 15th Feb 2023 but died
Larva 2 - Pupated 13th Mar 2023 but died
Larva 3 - Pupated 28th Mar 2023 and emerged on 26th April (after 29 days)
Larva 4 - Pupated 29th Mar 2012 and emerged on 26th April (after 28 days)
Larva 5 - Pupated 4th Apr 2023 and emerged on 1st May (after 27 days)
Larva 6 - Pupated 15th Apr 2023 and emerged on 7th May (after 22 days)
Larva 7 - Pupated 15th April 2023 and emerged on 9th May (after 24 days)
Larva 8 - Pupated 16th April and emerged on 11th May (after 25 days)
Larva 9 - Pupated 30th Apr 2023 and emerged on 18th May (after 18 days)
Larva 10 - Pupated 18th May 2023 and emerged on 1st June (after 14 days)


Vince

[Vince Massimo]

Over the winter of 2016 and through to August 2017, I carried out further studies of this species, particularly with regard to the overwintering larval stages. As a result, the original report of 2011 has now been updated with many new images (all those dated 2017 and some from 2016). The following report will now cover the development of an individual overwintering larva (which, unusually went through 6 instars) and also include a complete and updated sequence documenting a larva through pupation and on to the emergence of the adult.

On 31st October 2016 I found 2 Red Admiral eggs on a patch of nettles growing in the shelter of a south-facing wall on the seafront at Lancing, Sussex. They were both placed on the edge of a leaf and could therefore easily be confused with the eggs of a Comma (but it was too late in the year for eggs of that species).

Red Admiral eggs - Lancing, Sussex 31-Oct-2016

On egg failed to hatch and the other produced a larva on 9th November 2016. It was given some shelter over the coming winter, but nevertheless developed very slowly. By the time the larva had reached its 5th instar, on 14th March 2017, it was smaller than expected and then surprisingly moulted again on 27th March into its 6th instar. It achieved a final length of over 35mm, pupating on 3rd April and producing an enormous adult female on 23rd April 2017.

A possible explanation for the extra instar in this case comes from an interesting study in Finland on the Glanville Fritillary, where it was found that larvae that were under-developed (based on their body mass) would occasionally produce an extra instar. However this would not appear to be the case in many other instances, where undersized larvae just end up producing undersized adults (as happens in drought years).

Red Admiral 1st instar larva - Crawley, Sussex 15-Nov-2016

Red Admiral 1st instar tent - Crawley, Sussex 23-Nov-2016

Red Admiral 2nd instar larva - Crawley, Sussex 9-Jan-2017

Red Admiral 3rd instar larva - Crawley, Sussex 12-Feb-2017

Red Admiral (early) 4th instar larva - Crawley, Sussex 1-Mar-2017

Red Admiral 4th instar larva - Crawley, Sussex 8-Mar-2017

Red Admiral (early) 5th instar larva - Crawley, Sussex 14-Mar-2017

Red Admiral 5th instar larva - Crawley, Sussex 20-Mar-2017

Red Admiral (early) 6th instar larva - Crawley, Sussex 28-Mar-2017

Red Admiral 6th instar larva - Crawley, Sussex 1-Apr-2017

Red Admiral 6th instar larva - Crawley, Sussex 2-Apr-2017

Red Admiral 6th instar larva (pre-pupation) - Crawley, Sussex 3-Apr-2017

Red Admiral pupa - Crawley, Sussex 5-Apr-2017

Red Admiral pupa - Crawley, Sussex 23-Apr-2017

Red Admiral emerging - Crawley, Sussex 23-Apr-2017

Red Admiral release - Crawley, Sussex 23-Apr-2017

Develoment took place as follows:
Egg laid on 12-Oct-2016 (estimated)
Egg found on 31-Oct-2016
Egg hatched on 9-Nov-2016 (after approx 28 days)
First instar for 31 days (moult to 2nd on 1-Dec-2016)
Second instar for 66 days (moult to 3rd on 13-Feb-2017)
Third instar for 17 days (moult to 4th on 1-Mar-2017)
Fourth instar for 13 days (moult to 5th on 14-Mar-2017)
Fifth instar for 13 days (moult to 6th on 27-Mar-2017)
Sixth instar for 7 days
Pupated on 3-April-2017
Emerged on 23-April-2017 (after 20 days)
Total of 167 days from egg hatch to adult

Paul Harfield also observed a larva going through 6 instars over the winter of 2014/2015 in Wiltshire, although it subsequently failed to produce an adult. Paul also documented the development of an overwintering larva in 2016/2017 which produced an adult on 19th May 2017.

In spring 2017 I found several other overwintering larvae of this species. The advanced development of the larvae clearly indicated that they could not have originated from spring eggs. The earliest report of eggs in 2017 for this species was 10th March.

27th March 2017 – 4th instar at the seafront at Lancing, Sussex
27th March 2017 – 5th instar at the seafront at Lancing, Sussex
Both were in the same nettle bed where eggs were found the previous October.
6th April 2017 – 3 x 5th instars at North Stoke (near Amberley), Sussex
11th April 2017 – 5th instar at North Stoke (near Amberley), Sussex
These were in a south facing nettle bed at the base of an escarpment.

Throughout much of 2017 I reared or observed many more larvae, either from eggs laid in the garden or rescued from vulnerable locations along the public highway. This enabled me to produce an updated sequence of images documenting a larva through pupation and then emergence as an adult.

Red Admiral 5th instar larva - Crawley, Sussex 12-Apr-2017

Red Admiral larva (preparing to pupate) - Crawley, Sussex 14-Apr-2017

Red Admiral larva (commencing pupation) - Crawley, Sussex 14-Apr-2017

Red Admiral larva pupating - Crawley, Sussex 14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

14-Apr-2017

Red Admiral pupa (attaching cremaster) - Crawley, Sussex 14-Apr-2017

Red Admiral pupa (newly emerged) - Crawley, Sussex 14-Apr-2017

Red Admiral pupa (15 mins old) 14-Apr-2017

Red Admiral pupa (30 mins old) 14-Apr-2017

Red Admiral pupa (1 hour old) 14-Apr-2017

Red Admiral pupa (3 hours old) 14-Apr-2017

Red Admiral pupa (6 hours old) 14-Apr-2017

Red Admiral pupa (13 days old) - Crawley, Sussex 27-Apr-2017

Red Admiral pupa (37 hours before emergence) - Crawley, Sussex 28-Apr-2017

Red Admiral pupa (21 hours before emergence) - Crawley, Sussex 29-Apr-2017

Red Admiral pupa (12 hours before emergence) - Crawley, Sussex 29-Apr-2017

Red Admiral pupa (45 mins before emergence) - Crawley, Sussex 30-Apr-2017

Red Admiral emerging - Crawley, Sussex 30-Apr-2017

Red Admiral emerging - Crawley, Sussex 30-Apr-2017

Red Admiral emerging - Crawley, Sussex 30-Apr-2017

Red Admiral emerging - Crawley, Sussex 30-Apr-2017

Taking into account all data collected from various sources between 2014 and 2023, the indications (to date) are that, as a general rule of thumb, all overwintering larvae resulting from eggs hatching in November and early December will have produced adults by 20th May. Furthermore, adults arising from spring eggs would usually be emerging after that date. In all these years of collecting data only one butterfly emerged after this date (on 1st June 2023) having pupated on 18th May. This was mainly a consequence of a very cold preceding winter and a cool spring.

EDIT May 2019 Following further observations over the winter of 2017/2018 new data shows that eggs laid in November can hatch in February the following year, which you would expect to push back the emergence date for adults into early June, however it has now been observed that eggs laid on 24th February 2019, which hatched on 14th March produced adults on 17th and 18th May.

All butterflies and larvae that were reared or observed were released at a safe location.

Vince

[David M]

Superb observations, Vince, backed up with a fantastic array of sequential images.

Interesting that the first Red Admiral larva was able to slow down its development over the late autumn/winter months (31 days in 1st instar & 66 days in 2nd instar).

[Pete Eeles]

Great work, as ever, Vince! I seem to have been rearing large numbers of parasites this year; I have to bite my lip every time I let one go

Cheers,

- Pete

[Vince Massimo]

Interesting that the first Red Admiral larva was able to slow down its development over the late autumn/winter months (31 days in 1st instar & 66 days in 2nd instar).

Thanks David, it seems that the development rates of winter instars are extremely variable. I Imagine that temperature is a primary factor, but do not have enough data to rule out other possiblities.

Great work, as ever, Vince! I seem to have been rearing large numbers of parasites this year; I have to bite my lip every time I let one go

Thanks Pete, it all counts as data

Vince

[Vince Massimo]

This is an account of personal observations made over the winter of 2017-2018 plus a summary of reports received form UKB members as found in this related topic: http://www.ukbutterflies.co.uk/phpBB/vi ... f=8&t=9581 . See also viewtopic.php?f=8&t=9984 for overwintering observations for 2018-2019 and in particular those supplied by Paul Harfield which are summarised at the bottom of this post.

The Red Admiral had an exceptional time over the winter of 2017-2018. This started with a gradual build up in the numbers of adults in the late summer months. This, in turn resulted in very many eggs being laid in late summer and autumn of 2017. I recorded 460 eggs in a 57m long nettle bed in the shelter of a south-facing cemetery wall in Crawley in November 2017.Other large concentrations were reported in Southwick on 28th October and in Knowle, (both in Hampshire) on 11th November by Paul Harfield. Eggs were observed being laid in September, October and November 2017 and whilst none were actually seen being laid in December, there is evidence of this from previous years. Further eggs were laid on 2nd February 2018 in Taunton, Somerset. (As reported on the Somerset and Bristol Branch BC Twitter feed) ) https://twitter.com/BCSomerset/status/9 ... pdates.php . Paul Harfield also reported evidence of egglaying between 28th January and 11th February, as well as on 17th February at his two sites in Hampshire. In previous years eggs were also seen being laid in March. Many reports were received of eggs and larva during the monitoring period. These came in mainly from southern counties, but some from as far north as Lincolnshire.

At my cemetery wall site in Crawley the nettles appear to have been cut in approximately mid-September and, as such, there was only a small amount of fresh re-growth. However this was all that was needed for the butterflies to utilise. Eggs were seen to be laid on 19th, 23rd and 26th November 2017 by two different females. Older eggs were also found, including some on other bits of live or dead vegetation close to the nettles.

Cemetery wall nettle bed - Crawley, Sussex 17-Nov-2017

Cemetery wall nettle bed - Crawley, Sussex 23-Nov-2017

Red Admiral female and egg - Crawley, Sussex 19-Nov-2017

Red Admiral female - Crawley, Sussex 19-Nov-2017

13 Red Admiral eggs - Crawley, Sussex 22-Nov-2017

12 Red Admiral eggs - Crawley, Sussex 30-Nov-2017

Red Admiral egg on twig - Crawley, Sussex 19-Nov-2017

On 9th December 2017, despite the air temperature being only 3C (and the base of the wall at 8C) I found two freshly hatched 1st instar Red Admiral larvae crawling about in the open. One was on a leaf next to a unhatched egg and the other was in the crown of the same plant looking for shelter.

Red Admiral larva (1st instar - newly emerged) - Crawley, Sussex 9-Dec-2017

Red Admiral larva (1st instar - newly emerged) - Crawley, Sussex 9-Dec-2017

There was also an older 1st instar larva nearby.

Red Admiral larva (1st instar) - Crawley, Sussex 9-Dec-2017

On 7th January 2018 I recorded a larva emerging from its egg.

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

On 17th February another egg was found to have hatched.

Red Admiral egg preparing to hatch - Crawley, Sussex 16-Feb-2018

One problem with keeping track of over-wintering eggs in the wild is that the leaves bearing them tended to shrivel and drop from the plants. For this reason several egg-bearing leaves were collected before they were dropped which enabled the eggs to continue to be monitored in captivity. In an effort to try to replicate the sheltered environment from which they came, the eggs were kept on potted plants which were given a good deal of protection. (This, after taking daytime and night time temperature readings from the wild site). However, I am aware that this also had the effect of reducing the risk of predation and therefore possibly skewing the results of the study.

One particular pair of eggs (taken into captivity on 6th February) appeared ready to hatch on 23rd February 2018. By the 25th the larvae had chewed through the tops of the eggs, but this is when the really cold weather hit the UK. For 5 days and 6 nights the temperature here did not get above freezing, with a low of minus 5C on 27th and 28th February (minus 2C in the plant protection area). The last sub-zero day was 2nd March (and the early hours of the 3rd). By 4th March the open eggs, were still unhatched and therefore presumed dead. However, on 6th March one was found to have hatched (this possibly happened on 5th March) and the larva was found the following day at the top of the plant. The egg was estimated to be at least 104 days old. At the same time the other larva was found to be slumped inside its egg and so was presumed to have died. The eggs remained open for approximately 8 days before one hatched and I now realise that I actually observed the beginning of something similar in the wild. One egg was seen to be open for 4 days during a cool spell, but I then lost track of it and presumed that the larva had died at the point of emergence.

Red Admiral eggs ready to hatch - Crawley, Sussex 23-Feb-2018

Red Admiral eggs (now open) - Crawley, Sussex 25-Feb-2018

Red Admiral eggs (still open) - Crawley, Sussex 4-Mar-2018

Red Admiral egg (found hatched) - Crawley, Sussex 6-Mar-2018

Red Admiral larva (recently emerged) - Crawley, Sussex 7-Mar-2018

On 11th March 2018 the penultimate captive egg hatched here in Crawley (it being taken into care on 22nd February). This particular one was laid at the cemetery wall site on 21st November 2017, which made it 110 days old. The larva had chewed part of the top of the egg away during the previous afternoon, and when I checked it again at 10.40 the following morning, it was half way out.

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

Of the 5 larvae that hatched from captive eggs on 11th and 18th February, and 5th, 8th and 11th March 2018, 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.

A visit to the cemetery wall site on 18th April found that there had been a lot of new growth and I could only locate 3 larval tents containing 4th or 5th instar larvae. This did not seem a lot, considering that egg count here last November was over 450. By 21st April these larvae too had disappeared.

Cemetery wall nettle bed - Crawley, Sussex 18-Apr-2018

However I revisited the cemetery wall site in Crawley on 27th May and found 6 late-instar larval tents, but they were all empty but then discovered a 5th instar larva out in the open on the edge of the nettlebed. It was in the same area where eggs were hatching in January, so it could have been a survivor of that period.

Red Admiral 5th instar larva - Crawley, Sussex 18-Apr-2018

On 19th April a visit to Lancing (Sussex) seafront produced 3 Red Admiral tents. They were in the same location where I had previously 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

Red Admiral larval tent and larva - Lancing, Sussex 19-Apr-2018

Ultimately, only one larva of all those monitored on different sites in Crawley was observed to successfully develop into an adult. On 18th September 2017 I saw eggs being laid which hatched on 30th September (after just 12 days). Most larvae from this batch of eggs got to 4th and 5th instars before succumbing to the winter weather. The single survivor developed in the following stages in captivity:

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)

The resulting adult was slightly undersized and overall its development took 216 days (seven months) from the date the egg was laid. Two months of that was spent as a 4th instar and three 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.

Red Admiral pupa - Crawley, Sussex 22-Apr-2018

Red Admiral (newly emerged) - Crawley, Sussex 22-Apr-2018

In summary, larvae were recorded as hatching in September, October, November, December 2017 and January, February and March 2018 and were seen to be active through those months. Some of those 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.

Worthy of special mention is a series of reports by Paul Harfield where he describes overwintering adults. He observed two Red Admirals roosting in his Hampshire garden over the winter of 2018/2019 - one for 33 days and the other for 92 days (27th October 2018 to 27th January 2019).
viewtopic.php?f=8&t=9984

Vince

[Pete Eeles]

Brilliant report Vince, as ever!

Cheers,

- Pete

[Chris Jackson]

Good report, Vince, with plenty of detail.

Chris

[David M]

Fabulous, Vince. You have been (as ever) meticulous in your collating of observations.

[Vince Massimo]

Thanks guys, there's always something new to be discovered every time I observe this species. Here is another installment.

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 (these can be either home-grown individuals 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 2019 at Ferring Rife on the Sussex coast and having studied the results, I can discount option No.3. 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 high winter temperatures were building. EDIT: A further piece of the jigsaw was provided by Bob Eade, who photographed a mating pair of Red Admirals in his garden in Seaford, Sussex on 26th January 2024. The temperature at the time was around 10C.
https://ukbutterflies.co.uk/phpBB/viewt ... 65#p183265
https://ukbutterflies.co.uk/phpBB/viewt ... 74#p183274
On the same day there was a report on Twitter (X) by Glynn Jones who saw a mating pair at 12.30 in St George's Hill, Weybridge, Surrey, but was unable to get a photo because they were too high on a branch.

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*

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

Red Admiral egg (2 days before hatching) - Crawley, Sussex 13-Mar-2019

Red Admiral 1st instar larva 15-Mar-2019

Red Admiral 2nd instar larva 27-Mar-2019

Red Admiral 3rd instar larva 4-Apr-2019

Red Admiral 4th instar constructing a new shelter 12-Apr-2019

Red Admiral 4th instar feeding from tent 13-Apr-2019

Red Admiral 4th instar larva 14-Apr-2019

Red Admiral 5th instar larva 22-Apr-2019

Red Admiral pupation tent 1-May-2019

Red Admiral pupa 14-May-2019

*Egg No.2 followed the same pattern, but was a day longer in the pupal stage. Both adults were released on the Sussex coast, quite close to where the eggs were collected.

Interestingly, the date of these emergences corresponds very well with those resulting from eggs hatching in November and early December, but more study is needed in order to understand what happens to this species outside of the traditional southern European winter breeding grounds.

Vince