Sunday, 20 May 2018
2017 was generally not a good year for butterflies here in South East Scotland, but strangely it was a very good year for Red Admirals, Vanessa atalanta.
In previous years the Red Admiral was considered to be a summer visitor to Scotland. They would arrive here from May to July from the continent and would lay eggs to produce the next generation, which it was thought either perished or returned south for the winter. However, over the last few years there have been a number of early sightings of Red Admirals here, suggesting that they are able to survive the milder winters we have had recently. Sadly, the long cold winter we have just had appears to have killed off all of the Red Admirals, but I notice that in southern England enthusiasts have found eggs and caterpillars throughout the winter.
The caterpillars nip the stems of nettles, causing the top to wilt over and then they create a little tent for themselves by stitching the edges of a leaf together.
Last year there were a lot of caterpillar tents seen and I decided to collect a couple to watch the caterpillars' development. I picked two nettles containing caterpillars on 22nd August and put them in a pot of water with other nettles for the caterpillars to feed on. It turned out the caterpillars were very close to forming into chrysalises.
Two days later, on 24th August, I noticed that one had formed a chrysalis on roof of the container.
The other caterpillar had made its way to the top of the container and woven silk to form netting on the plastic window. The next day this caterpillar was hanging by its tail end from its silk pad.
The following day, the 26th August, the second caterpillar was still hanging by its tail end. I took the cage outside and within 30 minutes saw it was now forming a chrysalis.
It was a further 28 days before a butterfly emerged from the first chrysalis on 20th September. The second chrysalis also took 28 days to eclose, with the butterfly emerging two days later.
Friday, 11 May 2018
The Peacock butterfly is reasonably common here in East Lothian. They over-winter as adult butterflies, seeking out dark places, such as old sheds and buildings, or deep in log piles in which to hibernate.
They are often the first butterfly of the year to be seen, appearing on a sunny day in February or March. The adults go on to breed and lay their eggs in large clusters on the underside of nettle leaves in May or June. Depending on the weather the eggs will go on to hatch about two weeks later. The caterpillars will take about four or five weeks before they pupate. They will remain as chrysalises for somewhere around two to four weeks, depending on the temperature.
So, there is one generation of this butterfly each year. The adult butterflies emerge here in August and their numbers peak around the middle of the month. They slowly reduce in numbers as they start to hibernate and by October we only see the odd sighting. However, after hibernation these same butterflies will be on the wing until June the following year. So, potentially, an adult can survive for up to ten months.
Last year I found an enormous group of caterpillars in a patch of nettles in a field where I walk our dog. I estimate that there must have been over 200 caterpillars there. I took this picture with my phone on 19th July, just as the weather took a turn for the worst.
The following day (the 20th) I collected three caterpillars and put them on some nettles I had picked, which I placed in a cage in the garage next to the window. They were at least out of the rain and protected from predators.
By the following evening, they were all hanging upside down from the nettles, looking as though they were about to pupate. They remained like that all day on Saturday 22nd, which was particularly wet and cold.
On Sunday morning, when I took a look, they had all turned into chrysalises.
During that period we had torrential rain for three days and when I took a look at the nettle patch I couldn't find any of the other caterpillars. I don't know if they had perished, or if they had also turned into chrysalises, which I couldn't find.
I had to wait for 24 days for my three chrysalises to emerge into butterflies on 15th August. I took the picture below before I went to work. You can see the pattern of the wing showing through the chrysalis.
The under-side of their wings is really well camouflaged among the dead nettle leaves, unlike the upper-side which is so beautiful.