Notes on Actias dubernadi 2023
Male Actias dubernadiIn January 2023, eggs of the stunning silk moth Actias dubernadi were advertised for sale on a specialist website (Actias.de)
The picture to the left shows a pink and yellow male and a pale green female behind.
I sent off my money and the seller confirmed that they had been posted to me on 19th January 2023. The seller was posting them to me from Poland.
Me, with the male mothI successfully reared this species of silk moth about 5 years ago and I fancied another try. The three pictures above show some adult moths from that time. The female moth is always a pale green colour and the male is pale pink and yellow.
Actias dubernadi, is not really a species for the beginner, and it requires quite specific rearing conditions for success. So I made my preparations in advance. One such preparation was to ensure that I had some small potted Scotch Pine trees. This is what the caterpillars need to eat.
Now I excitedly waited for them to arrive.
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January 2023
Waiting for the eggs of Actias dubernardi to arrive...
Around this time the Royal Mail suffered a hacking incident which affected international deliveries. I hoped my delivery would not be affected.
As the days went by, I grew concerned that the eggs had not arrived. They are said to hatch within 7-10 days of being laid by the adult moth. That does not leave a long time for them to travel to the UK at the best of times. And certainly now, with it being reported that international deliveries were experiencing long delays, it was going to be a push for them to arrive prior to them hatching.
Temperatures had dropped to -6 degrees C in the UK and I imagine they were similar, if not colder, in northern Europe.
Actias dubernadi are native to China and in the egg stage they would be in humid pine forests, not in the cold and dry environment of a package sitting somewhere between Poland and UK.
I considered the possibility that the eggs could have already died due to being too cold.
Or that they may have become too dry in the post and desiccated.
Or that the caterpillars may have tried to emerge while still packed in the postage tube, which would have either been too crowded for them to be able to emerge, or if successful, would have led to starvation.
All of these possibilities were very worrying - and grew even more so as each day passed.
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February 2023
I searched online in an attempt to see if the eggs can go through the winter in their natural habitat, but I could not find any information, other than there are two broods, and the winter is spent as a pupa in a cocoon. I could not find any studies on how long the eggs can survive nor what temperatures they can endure.
Being worried about the delay in their arrival, I asked the seller if those eggs he may have kept back for himself had hatched.
Sadly, the answer was that they had and were at L2 stage already.
This was not good news.
And still nothing arrived in the post. Weeks had passed by now and the chances of them being alive were looking remote. I was no longer excited about their arrival - but more dreading them arriving having died on the journey.
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6th February 2023
The eggs finally arrived on 6th February 2023, so they had been in the post (in unnatural conditions) for more than two weeks.
It was with great relief that I discovered, upon unpacking them, that they had not hatched in the post - but it was not clear whether they were alive or dead.
They were immediately removed from the plastic tube that they travelled in and placed on damp kitchen paper and placed in a plastic container and kept at room temperature with high humidity.
Next day (7/2/2023) I had a close inspection of the eggs. There were 32 eggs, some of which had clearly collapsed.
I separated them into two groups, those that had collapsed and those that appeared to have retained their shape.
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| Separated eggs |
Interestingly, there were 16 eggs in each group.
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| 16 collapsed eggs |
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| 16 eggs that were not collapsed |
7th and 8th February 2023
I have now put the two groups of eggs into separate containers, both kept at a temperature of approx. 18-19 degrees C and with a humidity of around 95%.
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| Larva No. 1 |
This was a fantastic discovery - at least I now knew that at least one egg had survived, and possibly another could also hatch. It also gave me new information about the conditions that the eggs could tolerate - information that I had not been able to find on the internet
I then checked the eggs to see if any others had hatched and wandered off.
All the eggs were accounted for, and one was clearly vacated. So, again luckily, I had found the only larva that had emerged, even though it had left the container after eating part of its eggshell, and could easily have been missed.
Later that day a second larva emerged and it was placed it in the pot with the pine and the first larva.
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The next day (09/02/2023), at 6am, I checked the eggs and larvae.
No more eggs had hatched.
I removed the kitchen paper (which was now discoloured) from where the eggs had been on the moist paper, replaced it with fresh paper and lightly sprayed the eggs and sealed the container.
Now I should note here, that most of the care and techniques I am applying (especially with respect to humidity and temperature) has been based on information gleaned from a great YouTube video produced by a young man called Bart Coppens.
Bart is Dutch but he speaks English very well. He has gained enormous experience through breeding and documenting many, many moths. As well as communicating with him online periodically, I have met him a couple of times when he has visited the UK.
Here, I hope, is a link to this hugely informative video, in his classic presentation style
https://www.youtube.com/watch?v=nfnTpbvThIE
Unlike most YouTube videos, which are typically quite short, Bart's videos are sometimes very long. In this case it is over two-and-a half hours long!
Bart is a fellow enthusiast and a prolific social media communicator. I am very grateful to him for sharing so much information about rearing moths.
Of the larvae, there were no signs of droppings, and the first larva was lying on the paper at the bottom of the container, apparently dead. The other larva was on the pine.
Later, I decided to photograph the larvae set up with the two larvae and when I did, I found that the “dead” larva had moved back onto the pine.
By the end of the day no further eggs had hatched.
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The two larvae have not moved all day, but there were a small number of droppings present which I took as a positive sign. You may just be able to see them in this photo.
Given the lack of movement, I wondered if they could be preparing to moult already? It seems very soon.
Larva No. 1, (left) after it had climbed back onto the pine, decided to stay near to the base of the pine needles - where it was actually quite sticky with what I assume is pine resin..jpeg)
Larva No. 2, (left) has tended to stay near to the end of the needles.
It is now Friday 10th February. Time for an update.
1. The eggs that arrived collapsed.
Unsurprisingly, nothing has emerged from the 16 collapsed eggs. I didn't really expect anything happen, but I retained them in similar conditions of humidity just in case.
2. The other eggs.
(What do I call them? Un-collapsed?, non-collapsed?, I'll go with "not collapsed" for now until I can think of a better term that means "not dried out but still fairly healthy-looking".
Nothing has changed with the remaining 14 (not collapsed) eggs. None have hatched - but also none have shown any signs of collapsing.
Are they dead inside the eggs? Was it just too long a period in the cold for them to survive with enough energy to hatch. Or are they (dare I hope?) still going to emerge?
3. The Larvae.
Turning to the two larvae, Larva No.1 one has again fallen off the pine and is lying in a slightly curved position on the paper on the floor of the contained.
I recall that when I observed it moving a couple of days ago, it did appear to be having a problem with its rear end and was repeatedly raising its anal claspers and attempting to get them to grip onto the pine needle. I'm not sure if it has actually ever eaten anything nor if it has been able to pass any droppings. The droppings I noticed earlier were nearest to larva No. 2 and so probably came from that one only.
I fear larva No.1 is now close to death. Probably only the humidity has sustained it. I will retain it separately and keep it under observation.
Larva No. 2 is still in the same position on the pine needle as it was yesterday.
However, when I lightly misted it, it slowly started to move its front end. Then after a minute or two it, again very slowly, turned around and began to walk back down the pine needle after inspecting and rejecting the part of the needle where it had previously fed.
I looked at it via a x10 lens, and could now see that its head was still very large in comparison to its body - and I could see that it clearly was not at all close to moulting. I did think that it would have been remarkably soon after hatching if it was indeed preparing to shed its first skin.
Perhaps this species is just a slow developing species that likes to take plenty of rest.
Perhaps it takes greater time to digest the pine needle than it would a caterpillar of a different species feeding on a different foodplant.
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Saturday 11th February.
Not much news today. The single larvae has continued to feed and produce plenty of droppings, so that seems to be doing fine at the moment.
No change with the eggs. None hatched, but none collapsed.
15/02/2023
The un-collapsed eggs still have not hatched.
I looked at another online video of A dubernadi eggs hatching and I noticed that the eggs were all white and I remembered that although most of the eggs I received were darkish green/brown, there were two that were white with only a few small light brown markings. These white ones were the only two to hatch.
So, perhaps the dark colour of the eggs indicates that something went wrong (e.g. too cold) and that died, but unlike the other 16 they did not / have not dried out and collapsed. I am still keeping them in a humid environment to monitor what happen. Will they rot and get smelly? Will they eventually collapse?
I may consider breaking one open and examining the contents under magnification.
The first caterpillar died after a few days; the other one is still alive and now preparing to make its first skin change from L1 to L2.
16th February 2023
Part way through the day the larvae changed skin. It is now at the stage called L2.
This is it just after I sprayed the pine today.
Below, I selected one of the eggs that had retained their shape and that I have been keeping humid in case they could still be alive. It is long past the date when they should have hatched, but for some reason they have not collapsed - however, it is now time to use one egg and find out if there is any sign of life inside it.
I carefully cut it in half, and as can be seen there was nothing inside. No liquid and no caterpillar.
So that seems to be the end of that then.
There is just the one lonely caterpillar, which is going to get all the attention. Lets hope it makes it through.
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23/02/2023
Larva changed skin. It is now L3
Reminder of the previous stages
Hatched egg
L1 Larva
L2 larva
24th March 2023
The caterpillar changed it skin and has been feeding well since. It is certainly consuming much more - I've had to move it to another potted pine.
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On the 6th April, I received 10 cocoons of A dubernardi from the same person who originally supplied the eggs. These arrived much quicker than the eggs that were sent earlier in the year (i.e. they spent less time in transit).
The picture shows my cocoon on the right and the ten new cocoons on the left.
The new cocoons have been cut open, prior to sending, to reveal the pupae inside. This had two advantages. 1. The seller was able to check that the pupae were alive and healthy-looking. 2. It is then possible to determine the sex of the pupae. I imagine he selected them to have a split between males and females, but I have not checked them yet.
They were well packed as can be seen below, and as a result they arrived safely.
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18 April 2023 - Male freshly emerged
As this newly emerged male made it's way up the cage for a suitable place to expand it's wings it seems unsure if is an adult moths or if it is still a caterpillar.
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20 April 2023 - Video of the adults
These moths were placed on the outside of the moth trap for this video. It was good to see them moving and how they reacted to the breeze.
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27/04/2023 - Eggs laid on Scots pine
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27 April 2023
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Cat on the prowl...
28 April 2023 - Some of the adult moths
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06 May 2023 - Coronation caterpillars
The first offspring of the April moths have hatched today - 4 larvae before 11:00 - just ahead of King Charles' coronation.
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28/05/2023
It appears that my remaining dubernardi larvae have picked up a virus or something similar. Despite keeping them in different environments (some out side on a potted and sleeved Scots pine, and some indoors in containers with cut sprigs of pine. They have all stopped developing and have been dying. Some got to the green stage, but appeared to be very small.
Actually, given the fact that they have been kept in separate groups, I wonder if it could be the case that they have a genetic weakness as the resulted from a sibling pairing.
I gave 30 larvae to one person and about twenty to another - so I'll be interested in hearing how they are getting on.
UPDATE: All of the larvae died - so something was wrong. I guess we'll never know what was the cause.
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