A walk to find the Brimstone's egg

Added: 2026-05-23

[00:00:03]It's pretty easy today, which has spoiled what was perfect start to the day. And indeed, when I started walking from home to this little lane, not far from it, it was blue skies, some fair weather cloud, but half way here, half of the sky was blue with nice white clouds in it. The other half of the sky was black.

[00:00:29]So, a little bit of a different video today.

[00:00:32]All I'm doing is having a walk down this lane here.

[00:00:36]As the sewage works to the side, and this is just a a farmer's track which leads to a range of fields. And I'm just going to have a look down this side, the sheltered side, to see what I can find.

[00:01:46]It's surprising what turns up if you just spend a little bit extra time just walking along the length of a hedge or down the side of a track like I am here.

[00:02:00]The more you look, the more you find.

[00:02:03]And a lot of Dilys's and my self records came from doing just this.

[00:02:12]And here's another one.

[00:02:14]This is the quite beautiful caterpillar of mottled umber.

[00:02:19]Mottled umber is a moth that we see late in the year and sometimes just into the new year.

[00:02:27]And this caterpillar is in its last instar.

[00:02:31]And almost on the way to being full grown.

[00:02:35]It's on blackthorn here.

[00:02:38]But it is a very attractive caterpillar, actually.

[00:02:43]One you can find for much of the spring and summer. It's one of the most common caterpillars that you'll find this time of year.

[00:02:54]Obviously, they're always around in large numbers. One turned up on on my yard, but that may have been imported with some blackthorn that I bought over the winter.

[00:03:06]So, our first species on this little stretch of track here.

[00:03:15]Now, here's a nice little thing. And this is a tortrix moth that Dilys and I never trapped. I don't think we ever attracted one of these to light at all.

[00:03:26]Most of our records of tortricina, if I remember right, came in this kind of manner. Found at rest on low vegetation during the day.

[00:03:39]This [snorts] isn't the best marked of tortricina.

[00:03:44]It's been through the wars a bit, judging by the boldness of the thorax.

[00:03:51]I'll put photo in of a better marked one, but it is a very attractive Bibio tricks.

[00:03:58]This is sort of tan brown color and there are almost silvery bluish stripes across the forewings.

[00:04:07]It's a lovely thing and some individuals can be better marked than others.

[00:04:11]But this is a nice find. It's a moth that I've not seen for a number of years.

[00:04:27]Now, here's a nice thing and hopefully the breeze won't take it out of the frame.

[00:04:32]Many of you will have seen a relative of this species, one of many all black Bibio flies, one in particular called Bibio marci, otherwise known as the St. Mark's fly because it has a habit of emerging in huge numbers very close to the late April St. Mark's Day.

[00:04:54]This, however, is a rarer thing and one of two Bibio that have red thoraxes and this is Bibio hortulanus. It's not a Bibio that I've ever come across a great deal.

[00:05:09]Usually quite close to woodland.

[00:05:13]And it's a year or two since I've seen this.

[00:05:17]But they're absolutely beautiful.

[00:05:20]Never see them in good numbers. Usually singularly.

[00:05:25]Occasionally you'll get two or three in a small area.

[00:05:30]But easily recognized by that red thorax.

[00:05:35]I'll say there is a very, very similar species, but I'm pretty certain this is hortulanus. Hortulanus is the only one that I've had in the Market Warsop area.

[00:05:48]It's a cracking thing and a really nice find.

[00:05:54]Remember at the back end of 2025 when I showed you how to find the small cases of Coleophora anatipennella?

[00:06:02]Well, they're much easier to find now and there's three full-grown cases the same as this one on this blackthorn and they stand out very easily. Just a quick scan of this blackthorn will reveal several more cases, I'm sure. I've already found three, but what a remarkable construction.

[00:06:23]Just a much enlarged version of the one that we saw in the autumn and the caterpillars are now free feeding on the leaves. They feed in typical blotch fashion.

[00:06:35]And the cases are really extreme for a pistol case as we term these. There are several species of Coleophora which construct similar cases, but this is the only one which does feed on blackthorn.

[00:06:51]But what a thing, an absolutely incredible thing. I've never seen this species full-grown like this.

[00:06:58]So, this is new to me.

[00:07:02]But it just shows you what you can find in a just a small stretch of hedgerow or woodland edge.

[00:07:12]And these are fantastic.

[00:07:21]They look very much like bird droppings.

[00:07:23]They're colored in the manner of a typical bird dropping.

[00:07:32]And while the other pistol case bearers create similar cases to this, these are the only ones I've seen that have this sort of black and white variegated patterning.

[00:07:49]They're absolutely super.

[00:07:52]And there's no recent sign of feeding, so these may well be in pupation, which obviously takes place inside the larval case here.

[00:08:05]So, that's Coleophora anatipennella, several cases on this stand of blackthorn.

[00:08:17]It's really surprising what can just turn up.

[00:08:21]Just a slow walk, good look at foliage, no beating trays, no sweep nets. Yes, you can find a lot more that way, but you also beat the living life out of a lot of softer-bodied invertebrates that way.

[00:08:38]I find it's much more pleasurable just to walk and search foliage visually.

[00:08:45]That's pretty much all diligence I ever did. It's just so much more enjoyable.

[00:08:52]It's surprising how you pick things out.

[00:08:54]You may think it's a just a forlorn task, but it isn't.

[00:09:11]Have a look at this.

[00:09:15]This is one of the Nomada bees.

[00:09:19]I'm not going to say what it is without having a good look and using some forms of reference.

[00:09:31]But, this is how Nomadas spend the period, certainly overnight, but obviously when it goes dull and slightly cool here, they cling on to stems and leaves, just as this is doing, by their jaws. [snorts] What an ingenious way to hang about and kill some time.

[00:10:03]And Nomadas are cleptoparasites and parasites of a range of solitary bees.

[00:10:16]They're great things. They don't sting.

[00:10:23]But they just sit like this all night long.

[00:10:41]Now, that little Nomada bee was on this shrub.

[00:10:46]Not a particularly easy find of a shrub, this. It's widespread, but you can go miles, literally, walking along hedgerows before coming across this particular shrub.

[00:11:00]And it's a buckthorn, Rhamnus cathartica, if I remember right.

[00:11:06]And buckthorn is the larval food plant of the brimstone butterfly. Now, we're getting a little bit late, but if you want to look for brimstone eggs, then don't leave it too much longer.

[00:11:22]And what you need to do is look on these young shoots.

[00:11:27]Buckthorn's quite a late opening shrub, so it will look a lot like this.

[00:11:34]And hopefully you may have a tiny brimstone butterfly egg underneath one of the leaves.

[00:11:43]And they are small, quite remarkably and surprisingly small for the size of the butterfly.

[00:11:51]When you lift up the young shoots, usually at the end of the growth, you should be lucky in finding these very conical but very narrow eggs.

[00:12:11]They start off pretty much like creamy white and then after a day they start to turn yellow.

[00:12:19]But they're remarkably slender and really they're not much any bigger than a than a ladybird egg. They're thinner than a ladybird egg, to be honest.

[00:12:31]If I turn it round, you may be able to see just how narrow they are.

[00:12:45]And I've no doubt that this will be one of many which has been laid on this particular buckthorn.

[00:12:53]And there will already be young caterpillars.

[00:13:02]Caterpillars when larger are very easy to find. You just look opposingly on the upper surface of the leaves.

[00:13:16]But if you're not sure what buckthorn looks like, it will look very different straight away in a hedge, a different sort of green.

[00:13:26]But the leaves, these are all young leaves that say it's only just really opening out here in Nottinghamshire.

[00:13:32]The leaves are oval.

[00:13:35]The buds are black.

[00:13:37]Like this, it's very distinctive in a hedgerow situation and you can just see the little green flower starting to form.

[00:13:48]They have lots of green flowers on.

[00:13:51]So, if you see a shrub with green flowers on, chances are it could be buckthorn.

[00:14:00]I've just been checking some of the garlic mustard or Jack-by-the-hedge >> [snorts] >> flower heads and the developing seed pods and an easy find is this very small orange-tip caterpillar. Can't remember whether this is probably late first instar or early second.

[00:14:19]But, easy to spot, always lying along a developing seed pod.

[00:14:25]They quickly become green and better camouflaged than what this one is.

[00:14:32]Still get a kick out of finding orange-tip eggs and the young caterpillars. We used to love to breed orange-tips.

[00:14:42]And they've had a good year by all accounts.

[00:14:47]So, although the wood flies are still around, you can now start look for the young caterpillars.

[00:15:02]As we get a few spots of rain, time to head home. But, I've enjoyed myself here.

[00:15:09]Just a 100-m stretch of farmland track, to be honest, right at the side of the sewage treatment works.

[00:15:17]There's a good range of trees and shrubs and some decent vegetation underneath those at the side of the track.

[00:15:26]It's surprising what turns up when you look.