Clouded Yellow (Early Stages)
- Vince Massimo
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Clouded Yellow (Early Stages)
The Clouded Yellow is a migrant to the shores of Britain and Ireland, arriving in varying numbers every year from its strongholds around the Mediterranean and North Africa. There can be up to three broods arising from the initial influx in May and June and there is a limited return migration in autumn. No stage of the butterfly is usually able to survive winters in most parts of Britain and Ireland, but in recent years there has been increasing evidence of larvae regularly overwintering in some sheltered southerly coastal locations. This species is also notable in that approximately 10% of the females are a pale form (f. helice).
The Egg
The principal larval host plants are clovers (Trifoliun spp.), but other important species are Bird’s-foot-trefoil (Lotus corniculatus) and Horseshoe Vetch (Hippocrepis comosa). Eggs are laid individually, usually on the upper sides of leaves. Their colour is white when freshly laid, turning gradually pale yellow and then orange after a few days.
In the hours prior to hatching the egg turns a dull purple/grey, with the larva chewing a hole near the top in order to emerge. *The use of flash shows the interior of the egg more clearly than usual in some of the photos.
Larva - General Behaviour
The Larva generally feeds in the open, on the upper side of a leaf. After feeding it will rest on a silk pad spun on the upper side of a leaf and facing away from the feeding area, usually towards the leaf stem. However, on small-leaved plants such as Horseshoe Vetch or Bird’s-foot-trefoil, where the larva may become too large to sit on an individual leaf, it may rest on a stem, usually head-down. It will moult on a silk pad spun usually on the upper side of a leaf, but on small-leaved plants, moults may also take place on a stem with the larva either facing head-up or head-down and the old larval skin is eaten after every moult. Larvae are tolerant of each other and will feed in close proximity without disturbance. As the larva grows, it becomes apparent that it has a mechanism in its rear end for flicking frass away from its body and the plant. Larvae were observed to feed by day and night, but this may not be typical behaviour in the wild.
First Instar
After hatching the larva immediately consumes the empty egg shell as its first meal. The first meals on the leaf are usually on the upper side and involve grazing on the outer cuticle, but without perforating it and leaving characteristic feeding damage. The first instar larva has a black head and is a greenish-yellow when first emerged, but gradually turns more yellow as it grows.
Second Instar
The second instar larva has a brownish-green colouration, with a pale brown head. A very faint white line may be visible at the base of its flanks as it approaches its next moult. When feeding it will now perforate the leaves, but will also feed on the sides of tender leaves.
Third Instar
The third instar larva now has a green head and body, with a white stripe along its flanks.
Fourth Instar
The fourth instar is initially similar in appearance to the previous stage but develops a faint row of yellowish-orange spots in the white line along its flanks, but only towards the end of its growth period. Larvae can be sexed at this stage of their development, but only when the body is back-lit. In this circumstance a pair of very faint elongated purple-grey patches can be seen under the skin on the back of the larva at its eighth segment. These patches are the developing testes of a male larva (and were found to be impossible to photograph). At this stage larvae will sometimes rest with the front part of their bodies slightly raised.
Fifth Instar
The fifth instar larva initially has the same colour and arrangement of yellowish-orange spots along its flanks as the fourth instar, but it is a noticeably darker green in colour compared to the pale green of the previous stage. This now makes sexing the larva more difficult. Stronger orange, yellow and black colouration in the side stripes develops gradually and can be quite variable between larvae. One of the larvae (L2) only developed yellow colouration and not the orange.
When fully grown, the larva will attach itself to a stem or other piece of vegetation by means of a silken pad at its tail and a silk girdle at its middle. This can be either in a vertical or horizontal position. Its colouration will pale and it will hang suspended in a “D” shape for around 24 hours before pupating.
The Egg
The principal larval host plants are clovers (Trifoliun spp.), but other important species are Bird’s-foot-trefoil (Lotus corniculatus) and Horseshoe Vetch (Hippocrepis comosa). Eggs are laid individually, usually on the upper sides of leaves. Their colour is white when freshly laid, turning gradually pale yellow and then orange after a few days.
In the hours prior to hatching the egg turns a dull purple/grey, with the larva chewing a hole near the top in order to emerge. *The use of flash shows the interior of the egg more clearly than usual in some of the photos.
Larva - General Behaviour
The Larva generally feeds in the open, on the upper side of a leaf. After feeding it will rest on a silk pad spun on the upper side of a leaf and facing away from the feeding area, usually towards the leaf stem. However, on small-leaved plants such as Horseshoe Vetch or Bird’s-foot-trefoil, where the larva may become too large to sit on an individual leaf, it may rest on a stem, usually head-down. It will moult on a silk pad spun usually on the upper side of a leaf, but on small-leaved plants, moults may also take place on a stem with the larva either facing head-up or head-down and the old larval skin is eaten after every moult. Larvae are tolerant of each other and will feed in close proximity without disturbance. As the larva grows, it becomes apparent that it has a mechanism in its rear end for flicking frass away from its body and the plant. Larvae were observed to feed by day and night, but this may not be typical behaviour in the wild.
First Instar
After hatching the larva immediately consumes the empty egg shell as its first meal. The first meals on the leaf are usually on the upper side and involve grazing on the outer cuticle, but without perforating it and leaving characteristic feeding damage. The first instar larva has a black head and is a greenish-yellow when first emerged, but gradually turns more yellow as it grows.
Second Instar
The second instar larva has a brownish-green colouration, with a pale brown head. A very faint white line may be visible at the base of its flanks as it approaches its next moult. When feeding it will now perforate the leaves, but will also feed on the sides of tender leaves.
Third Instar
The third instar larva now has a green head and body, with a white stripe along its flanks.
Fourth Instar
The fourth instar is initially similar in appearance to the previous stage but develops a faint row of yellowish-orange spots in the white line along its flanks, but only towards the end of its growth period. Larvae can be sexed at this stage of their development, but only when the body is back-lit. In this circumstance a pair of very faint elongated purple-grey patches can be seen under the skin on the back of the larva at its eighth segment. These patches are the developing testes of a male larva (and were found to be impossible to photograph). At this stage larvae will sometimes rest with the front part of their bodies slightly raised.
Fifth Instar
The fifth instar larva initially has the same colour and arrangement of yellowish-orange spots along its flanks as the fourth instar, but it is a noticeably darker green in colour compared to the pale green of the previous stage. This now makes sexing the larva more difficult. Stronger orange, yellow and black colouration in the side stripes develops gradually and can be quite variable between larvae. One of the larvae (L2) only developed yellow colouration and not the orange.
When fully grown, the larva will attach itself to a stem or other piece of vegetation by means of a silken pad at its tail and a silk girdle at its middle. This can be either in a vertical or horizontal position. Its colouration will pale and it will hang suspended in a “D” shape for around 24 hours before pupating.
- Vince Massimo
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- Location: Crawley, Sussex
Re: Clouded Yellow (Early Stages)
The Pupa
There are visible changes in the larva as it nears pupation. The main ones are that the larva elongates and sags a little, there is a darkening of the three segments behind the head and the absorption of the 4 pairs of pro-legs. Also, the absorption of the rear claspers results in the tail appearing thinner and darker.
A full sequence looks like this.
As in most other butterfly species, the pupa colours-up as the adult develops inside, particularly so nearing emergence. The colours are strongest when the butterfly is fully developed, but they pale slightly when the butterfly draws air into the pupa, which causes the wings and body to break contact with the inner surface of the pupal case. At this stage some, but not all, of the abdominal segments of the pupal case become distended.
It is apparent that the male in the above sequence has a lot of yellow hairs on the black tips of the forewings, but these become less obvious as the wings expand. However, the margins of the hindwings were completely black.
That was the development of a male pupa. The following is a female sequence.
Also note that two of the three butterflies ejected menconium into the empty pupal case as they emerged.
Note that (apart from the usual yellow spots) the female has uniformly black wingtips, without the widespread yellow hairs of the male.
This is a typical wing inflation sequence (in this case a male).
Background and Observations
Three eggs were found on Greater Bird’s-foot-trefoil (Lotus pendunculatus) on 12th September 2020. The plant was growing in shingle at the back of the beach at Lancing, Sussex. Two eggs were orange in colour and on adjacent leaves, suggesting that they were laid at the same time, while the third was pale yellow and on another part of the plant. This part of the beach has hosted good numbers of fresh Clouded Yellows in the past two years of observations, suggesting that they breed in this location during the summer. However, as the site is very exposed, it seemed unlikely that larvae could survive the winter.
The decision was taken to rear the larvae indoors in order to try to get the resulting adults to emerge before November and thus give them a better chance of either migrating south or finding a mate. In these circumstances the following development rates may not be typical for this species, but are given only as context.
12-Sept-2020 – 3 Eggs found (L1, L2, L3)
L1 (female)
12-Sept-2020 – Egg found
15-Sept-2020 – Egg hatched
18-Sept-2020 – Moulted to 2nd instar (after 3 days and 4 hours as a 1st instar)
21-Sept-2020 – Moulted to 3rd instar (after 3 days and 3 hours as a 2nd instar)
26-Sept-2020 – Moulted to 4th instar (after 4 days and 16 hours as a 3rd instar)
2-Oct-2020 – Moulted to 5th instar (after 6 days and 2 hours as a 4th instar)
12-Oct-2020 – Pupated (after 9 days and 16 hours as a 5th instar)
24- Oct-2020 – Adult emerged (after 12 days as a pupa)
Total of 39 days from egg hatch to adult
L2 (male)
12-Sept-2020 – Egg found
15-Sept-2020 – Egg hatched
18-Sept-2020 – Moulted to 2nd instar (after 3 days and 7 hours as a 1st instar)
22-Sept-2020 – Moulted to 3rd instar (after 3 days and 11 hours as a 2nd instar)
26-Sept-2020 – Moulted to 4th instar (after 4 days and 15 hours as a 3rd instar)
3-Oct-2020 – Moulted to 5th instar (after 6 days and 8 hours as a 4th instar)
12-Oct-2020 – Pupated (after 9 days and 4 hours as a 5th instar)
24-Oct-2020 – Adult emerged (after 12 days as a pupa)
Total of 39 days from egg hatch to adult
L3 (male)
12-Sept-2020 – Egg found
16-Sept-2020 – Egg hatched
19-Sept-2020 – Moulted to 2nd instar (after 3 days and 10 hours as a 1st instar)
23-Sept-2020 – Moulted to 3rd instar) after 4 days and 17 hours as a 2nd instar)
29-Sept-2020 – Moulted to 4th instar (after 5 days and 6 hours as a 3rd instar)
5-Oct-2020 – Moulted to 5th instar (after 6 days and 15 hours as a 4th instar)
15-Oct-2020 - Pupated (after 9 days and 12 hours as a 5th instar)
30-Oct-2020 – Adult emerged (after 15 days as a pupa)
Total of 44 days from egg hatch to adult
The adults were reared in Crawley, but released back to their original location on the Sussex coast as soon as weather conditions would allow.
Some more timings, but of development in the wild and very early in the year were provided by Dave Harris. He reported that the Clouded Yellow eggs laid in his garden in Newhaven, Sussex on 28th March 2022 started producing adults on 15th June, after a pupal stage of 14-17 days. The host plant was Crown Vetch. The eggs began to hatch after 26 days and a total of 79 days elapsed between egg-laying and adult emergence. All adults had emerged by the 87th day.
Reference images of adults
Reading References:
The Butterflies of Britain and Ireland (Thomas and Lewington 2014)
UK Butterflies Website
There are visible changes in the larva as it nears pupation. The main ones are that the larva elongates and sags a little, there is a darkening of the three segments behind the head and the absorption of the 4 pairs of pro-legs. Also, the absorption of the rear claspers results in the tail appearing thinner and darker.
A full sequence looks like this.
As in most other butterfly species, the pupa colours-up as the adult develops inside, particularly so nearing emergence. The colours are strongest when the butterfly is fully developed, but they pale slightly when the butterfly draws air into the pupa, which causes the wings and body to break contact with the inner surface of the pupal case. At this stage some, but not all, of the abdominal segments of the pupal case become distended.
It is apparent that the male in the above sequence has a lot of yellow hairs on the black tips of the forewings, but these become less obvious as the wings expand. However, the margins of the hindwings were completely black.
That was the development of a male pupa. The following is a female sequence.
Also note that two of the three butterflies ejected menconium into the empty pupal case as they emerged.
Note that (apart from the usual yellow spots) the female has uniformly black wingtips, without the widespread yellow hairs of the male.
This is a typical wing inflation sequence (in this case a male).
Background and Observations
Three eggs were found on Greater Bird’s-foot-trefoil (Lotus pendunculatus) on 12th September 2020. The plant was growing in shingle at the back of the beach at Lancing, Sussex. Two eggs were orange in colour and on adjacent leaves, suggesting that they were laid at the same time, while the third was pale yellow and on another part of the plant. This part of the beach has hosted good numbers of fresh Clouded Yellows in the past two years of observations, suggesting that they breed in this location during the summer. However, as the site is very exposed, it seemed unlikely that larvae could survive the winter.
The decision was taken to rear the larvae indoors in order to try to get the resulting adults to emerge before November and thus give them a better chance of either migrating south or finding a mate. In these circumstances the following development rates may not be typical for this species, but are given only as context.
12-Sept-2020 – 3 Eggs found (L1, L2, L3)
L1 (female)
12-Sept-2020 – Egg found
15-Sept-2020 – Egg hatched
18-Sept-2020 – Moulted to 2nd instar (after 3 days and 4 hours as a 1st instar)
21-Sept-2020 – Moulted to 3rd instar (after 3 days and 3 hours as a 2nd instar)
26-Sept-2020 – Moulted to 4th instar (after 4 days and 16 hours as a 3rd instar)
2-Oct-2020 – Moulted to 5th instar (after 6 days and 2 hours as a 4th instar)
12-Oct-2020 – Pupated (after 9 days and 16 hours as a 5th instar)
24- Oct-2020 – Adult emerged (after 12 days as a pupa)
Total of 39 days from egg hatch to adult
L2 (male)
12-Sept-2020 – Egg found
15-Sept-2020 – Egg hatched
18-Sept-2020 – Moulted to 2nd instar (after 3 days and 7 hours as a 1st instar)
22-Sept-2020 – Moulted to 3rd instar (after 3 days and 11 hours as a 2nd instar)
26-Sept-2020 – Moulted to 4th instar (after 4 days and 15 hours as a 3rd instar)
3-Oct-2020 – Moulted to 5th instar (after 6 days and 8 hours as a 4th instar)
12-Oct-2020 – Pupated (after 9 days and 4 hours as a 5th instar)
24-Oct-2020 – Adult emerged (after 12 days as a pupa)
Total of 39 days from egg hatch to adult
L3 (male)
12-Sept-2020 – Egg found
16-Sept-2020 – Egg hatched
19-Sept-2020 – Moulted to 2nd instar (after 3 days and 10 hours as a 1st instar)
23-Sept-2020 – Moulted to 3rd instar) after 4 days and 17 hours as a 2nd instar)
29-Sept-2020 – Moulted to 4th instar (after 5 days and 6 hours as a 3rd instar)
5-Oct-2020 – Moulted to 5th instar (after 6 days and 15 hours as a 4th instar)
15-Oct-2020 - Pupated (after 9 days and 12 hours as a 5th instar)
30-Oct-2020 – Adult emerged (after 15 days as a pupa)
Total of 44 days from egg hatch to adult
The adults were reared in Crawley, but released back to their original location on the Sussex coast as soon as weather conditions would allow.
Some more timings, but of development in the wild and very early in the year were provided by Dave Harris. He reported that the Clouded Yellow eggs laid in his garden in Newhaven, Sussex on 28th March 2022 started producing adults on 15th June, after a pupal stage of 14-17 days. The host plant was Crown Vetch. The eggs began to hatch after 26 days and a total of 79 days elapsed between egg-laying and adult emergence. All adults had emerged by the 87th day.
Reference images of adults
Reading References:
The Butterflies of Britain and Ireland (Thomas and Lewington 2014)
UK Butterflies Website
Re: Clouded Yellow (Early Stages)
I'm absolutely in awe of this, Vince. Absolutely first class work, both the written details as well as the imagery.
- Pete Eeles
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Re: Clouded Yellow (Early Stages)
Absolutely superb, Vince! This really is incredibly detailed; you've raised the bar once again ![Smile :)](./images/smilies/icon_smile.gif)
I look forward to your in-depth studies on the Southern Small White![Smile :)](./images/smilies/icon_smile.gif)
Cheers,
- Pete
![Smile :)](./images/smilies/icon_smile.gif)
I look forward to your in-depth studies on the Southern Small White
![Smile :)](./images/smilies/icon_smile.gif)
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
Re: Clouded Yellow (Early Stages)
Fantastic report Vince, and clearly hours and hours of work have gone into these observations and photographs. Incredible detail. Great stuff!
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Re: Clouded Yellow (Early Stages)
That's a really helpful report, Vince. How on earth did you manage to catch each larva undergoing each moult? Did you have a team of eyes monitoring them?
Guy
Guy
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- Vince Massimo
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Re: Clouded Yellow (Early Stages)
Thanks David, Pete, Pete and Guy, I was very pleased how this project turned out because I got all the necessary images and sequences in one cycle. It usually takes a few seasons to complete a full report.
Guy - In my experience you need a minimum of 3 larvae to have a good chance of getting the necessary images. I always try to get all the images with the first larva, as these will let me know what to expect with the following larvae. However if I miss a stage with the first one, then I know the next larva is not far behind. Larvae are monitored on a regular basis and then more closely when a particular change is expected. There were some long sessions, with one all-nighter and an 11 hour stint on another day, but there was a lot of luck involved as well. Fortunately the majority of the action took place during daylight hours. The moults were a nice bonus, but I could not have got all four of them with fewer larvae.
Vince
Guy - In my experience you need a minimum of 3 larvae to have a good chance of getting the necessary images. I always try to get all the images with the first larva, as these will let me know what to expect with the following larvae. However if I miss a stage with the first one, then I know the next larva is not far behind. Larvae are monitored on a regular basis and then more closely when a particular change is expected. There were some long sessions, with one all-nighter and an 11 hour stint on another day, but there was a lot of luck involved as well. Fortunately the majority of the action took place during daylight hours. The moults were a nice bonus, but I could not have got all four of them with fewer larvae.
Vince
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Re: Clouded Yellow (Early Stages)
Fabulous piece Vince on one of my favourite butterflies. Thought you would be interested to know that the first Clouded Yellow I have heard of was seen yesterday 19.3.21 at Southbourne Undercliff. A good chance it was a locally emerged individual.
Re: Clouded Yellow (Early Stages)
Very interesting Mike. I hadn't expected any until April this year. I haven't even seen a Peacock yet!
M.
M.
- False Apollo
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Re: Clouded Yellow (Early Stages)
Initially I saw the report on the Birguides Information Service, then I saw the record on the the BC Dorset website together with an article about the sighting. Did not expect one this early, but I believe we have had March records in the past here, probably seen by yourself. The finder has put the record and a photo on the UK butterflies Facebook page. It will be interesting to see if any more are recorded on suitable days as it could be any locally emerged butterflies depart the area at this time of year.
- False Apollo
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Re: Clouded Yellow (Early Stages)
Caught up with a patrolling male Clouded Yellow early afternoon 22.3.21 at Southbourne Undercliff. It was in the same area as the first sighting on 19.3.21. The temperature was around 12c. Comparing photos, it seems to be the same individual. This was the only one I saw on a long coastal walk here. Chances are this did emerge here. I did note egg laying in this area in November 2020.
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Re: Clouded Yellow (Early Stages)
Superb study Vince, I do admire your patience and dedication,fab stuff.
Dave
Dave
Regards
Dave Browne
Dave Browne
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Re: Clouded Yellow (Early Stages)
Thank you for your hard work here, Vince.
My guess was that the species might have life cycled around much slower (if at all) in decreasing outside temperatures, from eggs in September, rather than an early summer brood.
If the species acted a bit like a frost tender plant, in cold weather and died, do we know, at what stage of it's life cycle, it was most, low temperature resistant?
#RoomTemperature
My guess was that the species might have life cycled around much slower (if at all) in decreasing outside temperatures, from eggs in September, rather than an early summer brood.
If the species acted a bit like a frost tender plant, in cold weather and died, do we know, at what stage of it's life cycle, it was most, low temperature resistant?
#RoomTemperature
Kind Regards,
- Vince Massimo
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- Joined: Sat Aug 16, 2008 7:36 pm
- Location: Crawley, Sussex
Re: Clouded Yellow (Early Stages)
Many thanks for your comments, Mike, Dave and Philip, sorry for the delay in responding.
Philip - I don't know if your question was meant for me or Mike, but I haven't studied this species in the wild, so don't have an answer. All I know is that larvae are able to overwinter as various instars in some sheltered southerly sites.
Vince
Philip - I don't know if your question was meant for me or Mike, but I haven't studied this species in the wild, so don't have an answer. All I know is that larvae are able to overwinter as various instars in some sheltered southerly sites.
Vince