The Magnificent Eight in a new light

Added: 2026-05-24

[00:00:08]Yes, once again, I am stood beneath a sallow.

[00:00:13]I know this is an oak, but there is sallow here.

[00:00:22]And of course, there's only one good reason that most of us stand underneath sallow bushes and look up through the leaves, it's because looking for purple emperor larva.

[00:00:37]I could come back at another time, a time when it's dark, because it's well known that purple emperor pupa fluoresce under UV light.

[00:00:54]But, fifth instar larva also fluoresce, especially the horn-like projections that come off the head, and they're quite remarkable.

[00:01:08]But, I'm not going to come up here in the early morning hours.

[00:01:13]It's something that I can do from the safety of my backyard.

[00:01:43]Funny that, in the last few years or so, Nick and Simon Brown and myself have only found one purple emperor larva on this tree.

[00:01:52]And yet, just across the path from it is another tree that has provided a number of larvae and it did again earlier on this year.

[00:02:07]No sign during daylight today, but last night I went moth trapping to Spurn Warren and got back at some silly hour, well, 2:00 is quite silly for me now now that I'm getting on a bit.

[00:02:23]But, while sat on the yard having a cup of coffee, I was suddenly reminded by a message from Nick Bramley earlier in the day about fitting star open over larvae fluorescing and being picked up in the wild by people out at night looking for them with UV torches.

[00:02:46]Having recently purchased a better UV torch, I thought I can do that while I'm sat here doing nothing. So, at 20 past 2:00 in the morning this morning I put my UV torch to the challenge and it works. The larvae, especially the horn like projections on the head, are quite remarkable. The rest of the body fluoresces, too, but it doesn't fluoresce to the extent that the horn projections do.

[00:03:19]And so, I started to get some footage and to take some photographs, too.

[00:03:26]And while I was taking some footage and moving the torch from one side to another, I noticed something I didn't expect.

[00:03:38]Never thought that I would see it.

[00:03:41]But, when you hold the UV torch and aim the light directly down onto the larvae, it stays Move the torch to either side and the larva physically rolls its body to maintain full contact, you could say, with that UV light to ensure that UV light stays directly above the larva. You can move it 180° or so to do the side and the larva will rock completely over.

[00:04:22]I was quite stunned and taken aback by such movement.

[00:04:28]But, why does the larva do it? Does it do it because it likes the UV light or does it do it for the other reason that the UV light hurts what eyes that larva has?

[00:04:41]Either way, it's quite remarkable and something that I never thought I never thought of, my mind never thinking of seeing it.

[00:04:52]And I tried it time and time again on different larva and they all did the same.

[00:04:58]But, of the magnificent eight that I have here in this cage, six of them are L5.

[00:05:10]In fact, eight of them are L5 now because the other two that were L4 have molted into L5.

[00:05:17]And so, they're growing nicely and pupation will start within a week or so from the first of the larva.

[00:05:27]But, it was looking under UV light and noticing the movement of the larva, how it rocks to the side, completely tilts the whole of its body so that the light goes down on the back of the larva.

[00:05:47]And it completely rolled again when this light was placed in another direction.

[00:05:54]It just astounded me. It really did.

[00:05:56]Just goes to show that you think you know yet again everything about a species when all along they often have little facets to their makeup that they hide.

[00:06:13]That's something for people to have a look and find out. You never know what they're hiding, these invertebrates.

[00:06:24]Especially the purple emperor larva.