Part 1 - The Peacock Eggs and Larvae
The Peacock is an iconic butterfly and its larvae are quite easy to find, but not many people have seen a Peacock pupa or can distinguish one from a Small Tortoiseshell (see: viewtopic.php?t=7156&start=10000 )
Eggs are laid in batches of 300-500 on the undersides of Common Nettle leaves, but unless you actually observe them being laid, they are quite difficult to find. The jade-green barrel-shaped eggs are laid in a compact mound, often piled 2 or 3 deep, which can take the female over an hour.
Upon hatching the young larvae spin a dense web of silk over the leaf and when this is consumed do the same thing at the growing tip of the plant, where they feed and rest communally. Safety in numbers is a defence strategy for this species, but living as a group also enables them to raise their body temperature above ambient levels, which means that they can remain active even in cooler conditions. They also need these higher temperatures in order to digest their food more efficiently.
Larval webs are easy to spot in June and early July and they seemed to be particularly abundant this year (2012) when I found 15 on sunny, sheltered nettle beds at a local site.
As the larvae grow and moult they move to different areas of the plant or fresh plants, leaving a trail of old webs, larval skins and droppings, making them even easier to locate.
By the time they are in their 4th instar they have acquired their black colouration with white spots, long dark spines and pale legs.
When ready to pupate a larva will usually leave the plant and spins a pad of silk on a stem or branch. Here it attaches itself, hanging head-down in the characteristic pre-pupation "J" shape for a day or two.
Just prior to pupation the larva straightens slightly and starts to pulsate its body. The skin also begins to look baggy, before suddenly splitting behind the head and gradually being sloughed off. This process appears particularly dramatic in this species because of the difference in colour between the old skin and the new pupa, which only serves to accentuate the variance in size between the two stages.
End of part one.
Peacock (Early Stages)
- Vince Massimo
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- Vince Massimo
- Administrator & Stock Contributor
- Posts: 1858
- Joined: Sat Aug 16, 2008 7:36 pm
- Location: Crawley, Sussex
Re: Peacock (Early Stages)
Part 2 - The Peacock Pupa
Peacock pupae come in two different colour forms depending on their environment. The blackish/grey form tends to be found in such places as dark tree trunks and fences, while the yellow/gold variety is usually located beneath leaves. All of mine pupated on nettle stems and twigs and were of the yellow variety.
They are similar in appearance to those of the Small Tortoiseshell, which also have "Horns and Thorns", but with subtle differences.
There are colour changes in the wing area of the pupal case approximately 36 hours before emergence. These colours continue to darken and spread, with the abdominal area being the last to be affected.
A few hours before emergence takes place the pupa takes on a markedly paler appearance as the wings and body of the adult break contact with the inner face of the pupal casing. The abdominal segments also distend as the butterfly draws in air through tubes linked to the spiracle openings in the sides of the pupa and starts to pump up its body, putting pressure on the pupal case.
End of part 2
Peacock pupae come in two different colour forms depending on their environment. The blackish/grey form tends to be found in such places as dark tree trunks and fences, while the yellow/gold variety is usually located beneath leaves. All of mine pupated on nettle stems and twigs and were of the yellow variety.
They are similar in appearance to those of the Small Tortoiseshell, which also have "Horns and Thorns", but with subtle differences.
There are colour changes in the wing area of the pupal case approximately 36 hours before emergence. These colours continue to darken and spread, with the abdominal area being the last to be affected.
A few hours before emergence takes place the pupa takes on a markedly paler appearance as the wings and body of the adult break contact with the inner face of the pupal casing. The abdominal segments also distend as the butterfly draws in air through tubes linked to the spiracle openings in the sides of the pupa and starts to pump up its body, putting pressure on the pupal case.
End of part 2
- Vince Massimo
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Re: Peacock (Early Stages)
Part 3 - The Emergence Sequence
The increased pressure on the pupal case causes it to split on either side of the position of the head.
I collected two batches of larvae for the purposes of preparing this report in 2012. The first was a group of 7 third-instars and then 11 second-instars 4 days later. There were three losses from the first group which were due to parasitism by Ichneumonid wasps (Phobocampe confusa). The grubs emerged while the larvae were preparing to moult into their 4th instar and formed characteristic 5mm long egg-shaped cocoons near the skins of their dead hosts. Interestingly, the adult wasps emerged at the same time as the butterflies from that batch. The pupal stage lasted 10 days for the butterflies and 20 days for the wasps.
On 4th June 2017, several cocoons formed by parasitic wasp Phobocampe confusa were found close to the corpse of a 4th instar larva. These produced adult wasps on 22nd and 25th June.
Also in 2017 I observed two species of parasitic Tachinid flies at work. Species #1 (Sturmia bella or similar) would creep around the outer edges of the larval web, laying its eggs on nearby leaves for the larva to accidentally injest. Species #2 (Phryxe vulgaris or similar) would land nearby and then dart in to lay an egg on a larva.
All the adult butterflies were released close to their original sites while the wasps escaped while being photographed......................
Additional Observations
Peacock pupae are extremely difficult to find in the wild because the larvae invariably disperse some distance away from the food plant to find a pupation site. However, very occasionally one will turn up on the host plant. Such was the case in September 2018 when I was alerted to the discovery of a pre-pupation larva and subsequent pupa at Mill Hill in Sussex. However this find turned out to be an even rarer event because the pupa was the result of an infrequent partial second brood. The story of the find and credits can be seen here: http://www.ukbutterflies.co.uk/phpBB/vi ... 40#p137057
Unfortunately, when I eventually got to the site some 2 weeks later I found that the pupa had been parasitised, probably by a Tachinid fly.
Reading References:
The Butterflies of Britain and Ireland (Thomas and Lewington 2014)
UK Butterflies Website
Vince
The increased pressure on the pupal case causes it to split on either side of the position of the head.
I collected two batches of larvae for the purposes of preparing this report in 2012. The first was a group of 7 third-instars and then 11 second-instars 4 days later. There were three losses from the first group which were due to parasitism by Ichneumonid wasps (Phobocampe confusa). The grubs emerged while the larvae were preparing to moult into their 4th instar and formed characteristic 5mm long egg-shaped cocoons near the skins of their dead hosts. Interestingly, the adult wasps emerged at the same time as the butterflies from that batch. The pupal stage lasted 10 days for the butterflies and 20 days for the wasps.
On 4th June 2017, several cocoons formed by parasitic wasp Phobocampe confusa were found close to the corpse of a 4th instar larva. These produced adult wasps on 22nd and 25th June.
Also in 2017 I observed two species of parasitic Tachinid flies at work. Species #1 (Sturmia bella or similar) would creep around the outer edges of the larval web, laying its eggs on nearby leaves for the larva to accidentally injest. Species #2 (Phryxe vulgaris or similar) would land nearby and then dart in to lay an egg on a larva.
All the adult butterflies were released close to their original sites while the wasps escaped while being photographed......................
Additional Observations
Peacock pupae are extremely difficult to find in the wild because the larvae invariably disperse some distance away from the food plant to find a pupation site. However, very occasionally one will turn up on the host plant. Such was the case in September 2018 when I was alerted to the discovery of a pre-pupation larva and subsequent pupa at Mill Hill in Sussex. However this find turned out to be an even rarer event because the pupa was the result of an infrequent partial second brood. The story of the find and credits can be seen here: http://www.ukbutterflies.co.uk/phpBB/vi ... 40#p137057
Unfortunately, when I eventually got to the site some 2 weeks later I found that the pupa had been parasitised, probably by a Tachinid fly.
Reading References:
The Butterflies of Britain and Ireland (Thomas and Lewington 2014)
UK Butterflies Website
Vince
Re: Peacock (Early Stages)
cracking report vince as usual. i think you'll find the wasps are the little black splodges under your camera case ![Laughing :lol:](./images/smilies/icon_lol.gif)
![Laughing :lol:](./images/smilies/icon_lol.gif)
- Vince Massimo
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Re: Peacock (Early Stages)
NopeChrisC wrote:cracking report vince as usual. i think you'll find the wasps are the little black splodges under your camera case
![Smile :)](./images/smilies/icon_smile.gif)
Vince
- Pete Eeles
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Re: Peacock (Early Stages)
Great report Vince. I especially liked the Ichneumon wasps (really!) and wish someone would write a work on the parasites of the British Lepidoptera!
Cheers,
- Pete
Cheers,
- Pete
Life Cycles of British & Irish Butterflies: http://www.butterflylifecycles.com
British & Irish Butterflies Rarities: http://www.butterflyrarities.com
British & Irish Butterflies Rarities: http://www.butterflyrarities.com