Peacock (Early Stages)

Peacock (Early Stages)

Postby Vince Massimo » Sat Aug 25, 2012 1:33 pm

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.

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

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

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Peacock ova - Coulsdon, Surrey 2-May-2013

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

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

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

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

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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.

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Peacock (1st instar web) - Coulsdon, Surrey 25-June-2012

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Peacock (1st instar web) - Coulsdon, Surrey 25-June-2012

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Peacock larvae (1st and 2nd instars) - Coulsdon, Surrey 25-June-2012

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

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Peacock larvae (2nd instar pre-moult group) - Caterham,Surrey 4-July-2012

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 3rd instar they have acquired their full silky-black colouration with white spots, long dark spines and pale legs.

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Peacock (3rd instar larval web) - Coulsdon, Surrey 15-July-2012

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Peacock larva (3rd instar) - Caterham, Surrey 12-July-2012

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Peacock larvae (3rd and 4th instars) - Caterham, Surrey 6-July-2012

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.

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

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

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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.

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

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

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

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

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

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

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

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

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


End of part one.
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Re: Peacock (Early Stages)

Postby Vince Massimo » Sat Aug 25, 2012 2:21 pm

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.

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

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

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

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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.

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

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

There are colour changes in the wing area of there pupal case approximately 36 hours before hatching. These colours continue to darken and spread, with the abdominal area being the last to be affected.

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

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

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

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

A few hours before hatching 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.

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


End of part 2
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Re: Peacock (Early Stages)

Postby Vince Massimo » Sat Aug 25, 2012 3:05 pm

Part 3 - The Hatching Sequence

The increased pressure on the pupal case causes it to split on either side of the position of the head.

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

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Peacock pupa (commencing hatching) - Caterham, Surrey 31-July-2012

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Peacock hatching

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Peacock hatching

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Peacock hatching

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Peacock hatching

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Peacock hatching

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Peacock (freshly hatched)

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Peacock (expanding its wings)

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Peacock (expanding its wings)

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Peacock (expanding its wings)

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Peacock (freshly emerged)


I collected two batches of larvae for the purposes of preparing this report. The first was a group of 7 second-instars and then 11 first-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 hatched 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.

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

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

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

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

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


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Re: Peacock (Early Stages)

Postby ChrisC » Sat Aug 25, 2012 3:41 pm

cracking report vince as usual. i think you'll find the wasps are the little black splodges under your camera case :lol:
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Re: Peacock (Early Stages)

Postby Vince Massimo » Sun Aug 26, 2012 5:51 pm

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


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

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Re: Peacock (Early Stages)

Postby Pete Eeles » Sun Aug 26, 2012 6:06 pm

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
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