Peacock (Early Stages)

[Vince Massimo]

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.

Female Peacock egg laying - Coulsdon, Surrey 19-May-2013

Female Peacock egg laying - Coulsdon, Surrey 19-May-2013

Peacock ova - Coulsdon, Surrey 2-May-2013

Female Peacock (resting after egg laying) - Coulsdon, Surrey 19-May-2013

Peacock courting pair - Chaldon, Surrey 15-Apr-2010

Peacocks egg laying - Coulsdon, Surrey 16-April-2014

Double batch of Peacock eggs - Coulsdon, Surrey 16-April-2014

Peacock and Small Tortoiseshell egg laying - North Stoke, Sussex 11-April-2017

Peacock eggs (L) and Small Tortoiseshell eggs (R) - North Stoke, Sussex 11-April-2017

Peacock eggs (1 day before hatching) - Coulsdon, Surrey 14-June-2013

Peacock eggs hatching - Coulsdon, Surrey 15-June-2013

Peacock eggs hatching - Coulsdon, Surrey 15-June-2013

Peacock larvae emerging - Coulsdon, Surrey 15-June-2013

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.

Peacock larvae (1st instars) - Crawley, Sussex 31-May-2017

Peacock larvae (1st and 2nd instars) - Crawley, Sussex 3-June-2017

Peacock larvae (2nd instars) - Crawley, Sussex 3-June-2017

Peacock larvae (2nd instar web) - Coulsdon, Surrey 25-June-2012

Peacock larvae 2nd instars (pre moult) - Crawley, Sussex 10-June-2017

Peacock larvae (2nd and 3rd instars) - Crawley, Sussex 10-June-2017

Peacock larvae (3rd instars) - Crawley, Sussex 11-June-2017

Peacock larva (3rd instar) - Crawley, Sussex 24-May-2017

Peacock larva (3rd instar) - Crawley, Sussex 24-May-2017

Peacock larva (3rd instar) - Crawley, Sussex 24-May-2017

Peacock larvae (3rd instars) - Crawley, Sussex 12-June-2017

Peacock larvae (3rd instars) - Crawley, Sussex 14-June-2017

Peacock larvae (3rd instars) - Coulsdon, Surrey 25-June-2012

Peacock larvae 3rd instars (pre moult) - Crawley, Sussex 14-June-2017

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.

Peacock larvae (3rd and 4th instars with parasitic fly) - Crawley, Sussex 15-June-2017

Peacock larva (4th instar) - Crawley, Sussex 29-May-2017

Peacock larva (4th instar) - Crawley, Sussex 28-May-2017

Peacock larvae (4th instars) - Crawley, Sussex 15-June-2017

Peacock larvae (4th instars) - Crawley, Sussex 17-June-2017

Peacock larva (4th instar) - Crawley, Sussex 29-May-2017

Peacock larva 4th instar (pre moult) - Crawley, Sussex 3-June-2017

Moulted larval skins from 4th instars - Selsey, Sussex 24-Aug-2017

Peacock larva (5th instar) - Caterham, Surrey 12-July-2012

Peacock larva (5th instar) - Crawley, Sussex 3-June-2017

Peacock larva (5th instar) -Selsey, Sussex 24-Aug-2017

Peacock larva (5th instar) - Crawley, Sussex 4-June-2017

Peacock larva (5th instar) - Crawley, Sussex 9-June-2017

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.

Peacock larva (spinning a silk pad) - Caterham, Surrey 15-July-2012

Peacock larva (awaiting pupation) - Caterham, Surrey 14-July-2012

Peacock larva (awaiting pupation) - Caterham, Surrey 14-July-2012

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.

Peacock larva (awaiting pupation) - Caterham, Surrey 16-July-2012

Peacock larva (preparing to pupate) - Caterham, Surrey 16-July 2012

Peacock larva (commencing pupation) - Caterham, Surrey 16-July-2012

Peacock larva (pupating) - Caterham, Surrey 16-July-2012

Peacock larva (pupating) - Caterham, Surrey 16-July-2012

Peacock larva (pupating) - Caterham, Surrey 16-July-2012

Peacock larva (pupating) - Caterham, Surrey 16-July-2012

Peacock larva (completing pupation) - Caterham, Surrey 16-July-2012

Peacock pupa (freshly formed) - Caterham, Surrey 16-July-2012

End of part one.

[Vince Massimo]

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.

Peacock pupa (freshly formed) - Caterham, Surrey 16-July-2012

Peacock pupa (30 minutes old) - Caterham, Surrey 16-July-2012

Peacock pupa (7 hours old) - Caterham, Surrey 16-July-2012

Peacock pupa (1 week old) - Caterham, Surrey 23-July-2012

They are similar in appearance to those of the Small Tortoiseshell, which also have "Horns and Thorns", but with subtle differences.

Peacock pupa (showing Horns and Thorns) - Caterham, Surrey 25-July-2012

Peacock pupa (showing Horns and Thorns) - Caterham, Surrey 25-July-2012

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.

Peacock pupae (showing different colour changes) - Caterham, Surrey 31-July-2012

Peacock pupa (36 hours before emergence) - Caterham, Surrey 24-July-2012

Peacock pupa (18 hours before emergence) - Caterham, Surrey 25-July-2012

Peacock pupa (4 hours before emergence) - Caterham, Surrey 30-July-2012

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.

Peacock pupa (1 hour 30 minutes before emergence) - Caterham, Surrey 26-July-2012

End of part 2

[Vince Massimo]

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.

Peacock pupa (25 minutes before emergence) - Caterham, Surrey 31-July 2012

Peacock (commencing emergence) - Caterham, Surrey 31-July-2012

Peacock emerging

Peacock emerging

Peacock emerging

Peacock emerging

Peacock emerging

Peacock (freshly emerged)

Peacock (expanding its wings)

Peacock (expanding its wings)

Peacock (expanding its wings)

Peacock (freshly emerged)

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.

Phobocampe confusa cocoons - Caterham, Surrey 8-July-2012

Phobocampe confusa (hatched cocoon) - Caterham, Surrey 28-July-2012

Phobocampe confusa (adult parasitic wasp) - Caterham, Surrey 28-July-2012

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.

Peacock larva with cocoon of Phobocampe confusa - Crawley, Sussex 4-June-2017

Parasitic wasp Phobocampe confusa - Crawley, Sussex 22-June-2017

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.

Parasitic tachinid fly (species #1) - Crawley, Sussex 16-June-2017

Parasitic tachinid fly (species #2) - Crawley, Sussex 9-June-2017

All the adult butterflies were released close to their original sites while the wasps escaped while being photographed......................

Peacock (reared and released) - Caterham, Surrey 1-August-2012

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.

Peacock pupa - Mill Hill, Sussex 29-Sept-2018

Peacock pupa (parasitised) - Mill Hill, Sussex 29-Sept-2018

Reading References:

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


Vince

[ChrisC]

cracking report vince as usual. i think you'll find the wasps are the little black splodges under your camera case

[Vince Massimo]

cracking report vince as usual. i think you'll find the wasps are the little black splodges under your camera case

Nope ...............They were too small and too quick for me, even after being in the fridge for 30 minutes.

Vince

[Pete Eeles]

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