East Lothian Butterflies 2023 Part 1

I have been collating the butterfly records from East Lothian for the last 11 years, so we now have good data to see how butterflies have been doing over this period. Of course we only record a very small fraction of the number of butterflies that occur in East Lothian, but it gives a pretty good picture.

2023 started off with a reasonably mild, but wet winter. However, there were a few colder spells and the frosts persisted into April. The year was punctuated with an unusually high number of easterly winds. There wasn't really a lot of sunshine until mid May, when we had a warm, sunny spell, but sadly that only lasted until half way through June! The remainder of the year was rather showery, with continuing east winds. This was only broken by a sunny week in early September and then back to cloud and rain! The first frost around the 12th October saw a sudden drop in the number of butterflies.

The weather can have an impact on the number of butterfly records received. This isn't necessarily because the butterflies aren't out and about when the weather is poor, but may be because recorders are less likely to be out looking for them. It is often the weather from the previous year that can have more of an impact, preventing the adults laying eggs, or heavy rain washing small caterpillars off their food plants.

Some species had a really poor year in 2023, but others did surprisingly well.

The first record I received was of 3 Peacocks seen on the 17th March and several more were seen over the next few days. They had a pretty good year, particularly later in the summer when the new generation appeared.

On 23rd March I received the first record of a Small Tortoiseshell. Nationally there is much concern about the reducing number of Small Tortoiseshells, yet here their numbers have been fluctuating, but not really showing a decline. The number of records in 2023 was just a little lower than the average of the previous ten years.

The third species that overwinters as an adult is the Comma and they had a particularly good year, being seen in high numbers later in the season. The first one was spotted on the 2nd April. It is interesting that these three species have similar life cycles, feeding on nettles as caterpillars and hibernating as adults, yet they each had different success rates in 2023.

The next butterfly to be seen was a Holly Blue on the 3rd April. This was the real success story of 2023, with them being spotted all over the county in good numbers. It seems funny to think that prior to 2019 they were rarely recorded in East Lothian. I received records of 377 Holly Blues last year.

Next were the whites with Small White, Large White and Orange Tips first being seen on the 3rd, 5th and 7th April. These three species all had a good year  with higher than average numbers being recorded. However, the Green-veined White didn't make an appearance until the 19th April and it had the worst year since I have been collating the butterfly records. It is difficult to understand why it did so poorly when the other white species did so well. My only suggestion is that I usually associate Green-veined Whites with river banks and damper areas. Possibly the dry springs that we have had the last two years haven't suited it. Hopefully the numbers may bounce back in the future.

The first Speckled Wood appeared on 7th April. They had a fantastic year in 2023 and were seen in particularly high numbers in early September. It is interesting to speculate why they did so well in a year when the weather wasn't what we wouldn't normally think of as ideal for butterflies.

The Wall Brown has slowly been increasing  in numbers over the last ten or twelve years in East Lothian. However, the number of records peaked in 2021 and since they have decreased again. Nationally there is concern about this species reducing in range and numbers and it had been thought that Wall Browns were spreading north in response to climate change. This year, we received the first record on 25th April with the summer generation being much more numerous than the spring generation.

Small Coppers are never really seen in big numbers. More often than not a male will take up territory on a sunny leaf and fly up when disturbed only to return to the same spot. The first record in 2023 was on 26th April and it wasn't a particularly good year for them, which I can only imagine was down to the weather.

Although Red Admirals appear to be able to survive our winters as eggs, caterpillars, chrysalises or adults, the vast majority of those we see in the early summer have flown up here from continental Europe. However, there are a few early records, which are likely individuals that have found somewhere sheltered to over-winter. Our first record last year was on the 4th May, so it is difficult to be sure where this individual spent the winter! 2023 proved to be a bumper year for Red Admirals with 1421 individuals being recorded. The highest figure since I started collating the records. There were an enormous number of records in the third week of June, pointing to a mass arrival from overseas.

I will continue this on the next post.

Late Commas

Just to update my previous post. The Comma chrysalis that I found on the outside of my study window emerged on the 11th October. It had been lovely and sunny, but only 10 degrees Celsius and by the time it had fully unfurled its wings and dried out the sun was no longer shining on it. Eventually, it turned head down and settled down for the night roosting on its chrysalis.

That night the temperature dipped to 1 degree Celsius and we had our first frost of the year, but luckily it was sunny again the next day. The sun was low in the sky and it took until 10.30 before the sun reached the Comma. However, at 10.50 it had warmed up sufficiently to fly away. The temperature was 6.8 degrees in the shade.

On the 6th October I found a fully-grown Comma caterpillar on a nettle in the old hen run. This was exceptionally late in the season, as most of the books say that the chrysalises should all have emerged by the end of September.

I picked the nettle it was on and put it in a mesh cage I have under an overhang of the roof. Two days later it was handing from the nettle in a J-shape and on the 10th October it formed a chrysalis. I was intrigued to see if it would emerge a few weeks later if we had mild weather, or if it would survive as a chrysalis until the spring.

Unfortunately, yesterday morning I spotted that it had emerged, but hadn't managed to fully pump up its wings and had perished. It must have emerged on the 26th November, as I had checked that morning and it was still a chrysalis. Over the weekend the maximum temperature had been 6 degrees and it had gone down to -2 at night.

It was sad that it hadn't made it, but interesting nonetheless. As is so often the case, I am left asking many questions. Is it normal for Commas to continue laying eggs so late in the season? Possibly I have just never noticed them before. Or is this a sign of climate change impacting on their behaviour?

All of these pictures were taken with my phone as I was having camera problems at the time!

Comma, Polygonia c-album

The number of Commas I have seen here has been increasing year on year. This year I haven't seen quite as many as I did last year, but it seems there may be more to come!

On 21 July I was distracted again, when I was working in my study, by a Comma butterfly flitting about on the nettles outside my window. I realised it was laying eggs, so made a mental note of where I had seen it and at lunchtime I checked out a particular nettle stem. There I found an egg in the centre of the underside of a leaf.

I picked the stem and kept it in a jar of water next to my desk to watch it develop.

On the 28th July I noticed it had hatched and there was a little black caterpillar, about 2mm long.

The caterpillar tended to be quite inactive and remain on its leaf, only moving once the leaf had more or less been completely eaten. I was hoping to be able to determine which instar it was as it grew, but I became completely confused! So, below are some pictures as it developed. In this one it is two days old.

Here it is 12 days old.

And here it is at 20 days old. Every time I moved the nettle in order to photograph the caterpillar it would contort.

And here it is at 21 days old.

When it was 29 days old it spun a silk pad on a leaf stem and hung straight down from it. Of course it curled up as soon as I tried to take a picture! It remained like this for a day.

On the 21st August it formed a lovely chrysalis, mostly dark brown with two golden spots.

Two weeks later on 4th September I noticed that the segments on the abdomen area of the chrysalis had started to stretch apart, so I thought the butterfly  would soon emerge.

I didn't expect it to emerge so soon, though. Half an hour later when I looked, there was a butterfly hanging there!

I took the stick that it was now on outside into the sun. The butterfly remained on the stick for a couple of hours, then flew off onto a fence post, where it remained until about 4pm before it flew off.

On the 13th of September I noticed another Comma had formed a chrysalis on the outside of my study window. As I write this, on the 7th October, it is still there. Yesterday I found a Comma caterpillar on a nettle, close to where I found the egg in July. It looks as though it is fully grown and about to pupate, but it seems really late in the season. It will be interesting to see when these two emerge and if there will be any more Commas flying this year.

Red Admiral, Vanessa atalanta

I am lucky enough to have a large floor-to-ceiling window in my study, which overlooks a weedy area of our woodland. I am often distracted from my work by a butterfly fluttering past and on quite a few occasions I have seen butterflies laying eggs there.

On the 1st July I spied a Red Admiral flitting about from nettle to nettle. I made a mental note of one nettle where it had landed and sure enough, when I looked later there was an egg.

I picked the nettle and popped it in a jar of water. The hole in the lid was only just large enough for the stem to fit through, so that the caterpillar can't fall in! On the 9th July the egg hatched, producing a little black caterpillar. It hung around on the small leaf the egg was laid on for a few days, but the leaf started to dry up, so I cut the leaf and put it onto a fresh nettle.

The caterpillar immediately climbed onto the fresh leaf and tried to stitch the edges of the leaf together. This was rather ambitious for such a small caterpillar. As it grew bigger it did manage to stitch the edges of the leaf together to form a tent. The caterpillar would spend all day inside its tent, only coming out at night to eat or construct a new tent. It was rare to see the caterpillar in the daylight during this time.

By early August it had reached a good size and after a period of frenzied eating I noticed that the caterpillar was hanging upside down inside its tent. On the 7th August I saw that it had formed a chrysalis.

The chrysalises have amazing metallic green marks on them.

On 21st August, I noticed that the chrysalis had darkened slightly, and I thought that the butterfly would be emerging in a couple of days. However, about an hour later I looked round to see a butterfly hanging from the leaf! 

It wasn't a particularly sunny day, but after a few hours the butterfly flew off to a nearby bush, to join the other Red Admirals feeding there.

So, this Red Admiral had been an egg for 9 days, a caterpillar for 29 days and a chrysalis for 14 days. I found another, much lighter, caterpillar in the nettles , which I put into a mesh cage on a nettle stem. A few days later it formed a chrysalis, but this one remained in that state for 21 days. It is interesting how much longer it took to emerge.

As I write this in the middle of September, there are still caterpillars and chrysalises on the nettles outside my window.  The number of butterflies has dropped over recent weeks, but Red Admirals have been really abundant. Last week I counted 67 of them on my Buddleias and I noticed a few days ago they are also feeding on Yew berries.

Red Admirals are usually the last butterflies I see each year, with them sticking around until the end of October. I presume they then fly south, but it always intrigues me that they stay here long after the first frosts.

Holly Blues, Celastrina argiolus, in East Lothian

I have mentioned the Holly Blue in many of my annual round-ups, but think it deserves a post of its own!

Since I started collating the butterfly records for East Lothian in 2007 there has been the odd record each year of a Holly Blue. When I was working as a Countryside Ranger in the late ‘90s there was an established colony of Holly Blues on the western boundary of East Lothian at Newhailes and Brunstane. They were more or less unheard of anywhere else in Scotland at the time and there was a bit of suspicion about how they had arrived there.

Despite the knowledge that they were regularly seen in the Newhailes/Brunstane area there are surprisingly few records for Holly Blues in that area.

Over the next few years I received records of one or two Holly Blues each year. These were mostly from coastal towns in the north of the county. In the spring of 2011 there was great excitement when I spotted three Holly Blues on a Holly bush in Aberlady. Unfortunately, there were no records of a second generation that summer, or any subsequent records from that site.

By 2013 the Newhailes colony appeared to have died out and I feared that two poor summers in a row had wiped out Holly Blues in East Lothian. However, I received one record in 2014, 2015 and 2016 from those towns in the north of the county, leading me to believe that somewhere in that area was a little colony, possibly in a large private garden.

Then in 2017 and 2018 I didn’t receive any records. But, in 2019 there was great excitement on Facebook, as someone had found a number of Holly Blues outside a garden on the edge of a golf course in Gullane. Later in the year they were also regularly spotted in two other locations in the village. That year I received 28 Holly Blue records.

The excitement grew the following year when Holly Blues were spotted in various villages about 8 miles away from Gullane. By the end of 2020 I had received records of 90 Holly Blue being seen.

In 2021 the expansion of the range and population continued, with Holly Blues being quite regularly spotted and reported to me. Again they had advance by about 8 miles  following old railway walks and river valleys.  By the end of the year I had received records of 101 Holly Blues.

And in 2022 the trend continued with 288 Holly Blues being reported to me from much of the county. By this time they had spread to Edinburgh and there were some sightings in the Scottish Borders.

Already this year they have spread further across the county and a good number have been seen in the Borders, Edinburgh and Midlothian. I can't believe that this little butterfly has managed to colonise the entire county in just four years!

The Holly Blue has two generations a year. The first being seen in April and May and the summer generation flying in late July and August. We have also seen the odd Holly Blue in October and November, as a very small third generation. During their flight periods it is worth checking any sunny patches of ivy or holly for these little silvery-blue butterflies.

In England the populations of Holly Blues fluctuate considerably over a five year cycle. This is because of a parasitic wasp, Listrodomus nycthemerus, for which the Holly Blue is its only host. The population of Holly Blues can be decimated, but the following year the wasp has very few hosts causing a drop in its own numbers. As the Holly Blues continues to extend its range in Scotland it will eventually join up with the English population and, possibly, the parasitic wasp!

Small White, Pieris rapae

The pictures on this post were all taken with my phone, so apologies for a little fuzziness!

Last year, much to my wife’s annoyance, I found a number of Small White caterpillars feeding on some Rocket plants that she was growing. As they grew larger and started to destroy the plant, I put the pot in a mesh butterfly cage and fed the caterpillars with cauliflower leaves.

The caterpillars grew quickly and started forming chrysalises around the cage and under the rim of the plant pot saucer.

A couple of days before they form a chrysalis they choose a spot and weave a small silk pad. They then hook themselves to the pad and loop another length of thread like a girdle around themselves.

The caterpillar then thickens over the next couple of days and sheds its skin one final time. The chrysalis then forms over the next few hours. The picture below shows a newly formed chrysalis.

I kept an eye on them and at the end of October I noticed one of the chrysalises had started to colour up. Normally, this is something I see about four days before a butterfly emerges. As they reach the final stages of development the pattern on the underside of the wings becomes apparent through the wall of the chrysalis. I had always thought that once this final stage of development had started, there was no stopping it. So, I was expecting to see a very late third generation Small White, but the weather took a turn for the worse and the butterfly did not emerge.

I periodically checked the chrysalises over the winter and this April when I turned the saucer over I saw that the butterfly had started to emerge, but must have become stuck half way out and it had perished. Although this was sad for this individual, it proved that a chrysalis is able to survive for six months over the winter at this late stage of development.

Between the 25th April and the 28th May 29 Small White butterflies emerged from the 38 chrysalises around the cage. 22 of them were females and only 7 were males.

Seven of the chrysalises turned black or brown over winter and failed to develop. However, there is one in the cage that still looks as though it could be OK.