0:00:02 > 0:00:05This programme contains scenes of repetitive flashing images.
0:00:05 > 0:00:11Every spring, a tiny hero of the insect world undertakes a journey that almost defies belief.
0:00:11 > 0:00:12Weighing less than a gram,
0:00:12 > 0:00:18the intrepid Painted Lady butterfly migrates a staggering 2,000 miles
0:00:18 > 0:00:23from the Atlas Mountains in Morocco, all the way to the UK and beyond.
0:00:23 > 0:00:25Right now, across Britain,
0:00:25 > 0:00:28hundreds and thousands of butterflies
0:00:28 > 0:00:31are arriving on our shores after an epic journey.
0:00:32 > 0:00:35I'll be following that incredible journey
0:00:35 > 0:00:37as it advances across Europe.
0:00:37 > 0:00:38Painted Lady.
0:00:40 > 0:00:42With the help of insect expert Dr James Logan,
0:00:42 > 0:00:44we'll be unpacking the science
0:00:44 > 0:00:47behind a migration of immense proportions.
0:00:47 > 0:00:49That's amazing. It's actually following your finger.
0:00:49 > 0:00:51I'm going to be charting the progress
0:00:51 > 0:00:54of our butterfly spotters from across the country
0:00:54 > 0:00:55with the help of this fantastic team.
0:00:55 > 0:00:57Quick, quick, quick. Painted Lady.
0:00:57 > 0:01:02And we have a dedicated army of butterfly enthusiasts on the ground
0:01:02 > 0:01:04helping us.
0:01:04 > 0:01:07Working closely with leading butterfly experts
0:01:07 > 0:01:11and using hi-tech experiments and the very latest science,
0:01:11 > 0:01:15we're unravelling one of nature's greatest migratory mysteries
0:01:15 > 0:01:18and perhaps revealing for the first time
0:01:18 > 0:01:20the answer to the greatest puzzle of all -
0:01:20 > 0:01:23just why do they migrate in the first place?
0:01:24 > 0:01:28This is the story of the greatest insect migration on Earth.
0:01:28 > 0:01:35This programme contains scenes of Repetitive Flashing Images.
0:01:37 > 0:01:40Rothamsted Research Centre in Hertfordshire
0:01:40 > 0:01:43is the world's leading centre in insect science.
0:01:43 > 0:01:46Here, they unlock mysteries from the insect world
0:01:46 > 0:01:50with some quite extraordinary technology.
0:01:50 > 0:01:53So where better to track this year's migration of the Painted Lady?
0:01:54 > 0:01:58In their grounds, we've set up a special butterfly hub,
0:01:58 > 0:02:03which we're sharing with more than 700 Painted Ladies,
0:02:03 > 0:02:06so we can really get up close and personal
0:02:06 > 0:02:08with these extraordinary creatures.
0:02:08 > 0:02:10Alongside our butterfly hub,
0:02:10 > 0:02:14James has set up a communications centre to chart their arrival.
0:02:15 > 0:02:17All over the country,
0:02:17 > 0:02:20the public are getting involved by sending in their videos and pictures
0:02:20 > 0:02:23as Painted Ladies appear in Britain.
0:02:23 > 0:02:25She's the first one we've found in the garden this year.
0:02:25 > 0:02:28It's almost, like, magical when you actually see one.
0:02:28 > 0:02:30Painted Lady.
0:02:30 > 0:02:33And I'm going to be doing some incredible experiments
0:02:33 > 0:02:36to unlock the secrets of the Painted Lady migration,
0:02:36 > 0:02:40finding out exactly how and why they do what they do.
0:02:40 > 0:02:42Got it.
0:02:42 > 0:02:44Yes! Yes, I've done it.
0:02:44 > 0:02:48- Is that OK?- That's absolutely right. - Brilliant.
0:02:48 > 0:02:50This extraordinary migration begins
0:02:50 > 0:02:53in the North African deserts in winter.
0:02:53 > 0:02:56After breeding and building up their numbers,
0:02:56 > 0:02:58they set off in spring,
0:02:58 > 0:03:02heading across the Mediterranean to Europe and into the UK
0:03:02 > 0:03:05on a quite remarkable journey
0:03:05 > 0:03:07for a creature as fragile as a butterfly.
0:03:11 > 0:03:14The Painted Lady story is a fascinating one.
0:03:14 > 0:03:17I came to love butterflies through bees.
0:03:17 > 0:03:19I kept hives for many years
0:03:19 > 0:03:23and used to spot them out in wildflower meadows.
0:03:23 > 0:03:26Like most people, I'm enchanted by their colours and variety,
0:03:26 > 0:03:30but how many realise what this one species manages to achieve?
0:03:30 > 0:03:33The Painted Lady is a pretty familiar sight
0:03:33 > 0:03:35in most of our gardens,
0:03:35 > 0:03:38which makes it easy to take for granted.
0:03:38 > 0:03:40So here's everything you need to know
0:03:40 > 0:03:43about these mini marvels in just a minute.
0:03:47 > 0:03:52Painted ladies are 5cm in length and weigh a mere 200mg,
0:03:52 > 0:03:55which is a tenth of the weight of a paperclip.
0:03:55 > 0:04:00Yet amazingly, they can fly 100 miles in a single day,
0:04:00 > 0:04:02the equivalent of us running four marathons,
0:04:02 > 0:04:05and do so at speeds of up to 30mph.
0:04:07 > 0:04:10They lay their eggs on thistles and nettles,
0:04:10 > 0:04:13the preferred food choice for hatching caterpillars.
0:04:16 > 0:04:19Painted Ladies are a global phenomenon,
0:04:19 > 0:04:24the most widely distributed and most successful butterfly in the world.
0:04:26 > 0:04:31They really are amazing creatures, and supreme travellers, of course.
0:04:31 > 0:04:34But why do they go on such a long journey
0:04:34 > 0:04:36and, actually, a really dangerous one?
0:04:36 > 0:04:39I've been to find out where it all begins.
0:04:50 > 0:04:54I've travelled over 1,200 miles to Morocco in North Africa.
0:04:58 > 0:05:02Flanked by the Sahara Desert and Atlas Mountains,
0:05:02 > 0:05:05Morocco is a dry and unforgiving place.
0:05:06 > 0:05:08It's early March,
0:05:08 > 0:05:10and the Painted Ladies have been busy
0:05:10 > 0:05:12mating and laying eggs here.
0:05:18 > 0:05:23Driving through this incredibly parched landscape,
0:05:23 > 0:05:27it's just so hard to imagine that this is where the butterflies
0:05:27 > 0:05:31that we see fluttering around our green English gardens come from.
0:05:32 > 0:05:37But they do. One man has a special fascination with them.
0:05:37 > 0:05:41Constanti Stefanescu is the world's leading expert on Painted Ladies
0:05:41 > 0:05:45and has been coming here for many years to find them.
0:05:45 > 0:05:49He's a Spanish lepidopterist from the Natural History Museum
0:05:49 > 0:05:51in Granollers, in Catalonia.
0:05:51 > 0:05:55Constanti has had many scientific papers published on the Painted Lady
0:05:55 > 0:05:58and is working on his latest one.
0:05:58 > 0:06:03Since I was a boy, I was very interested in animals in general,
0:06:03 > 0:06:07and butterflies in particular.
0:06:08 > 0:06:13Well, the Painted Lady is really a very special butterfly,
0:06:13 > 0:06:17because it's one of the very few that can move long distances.
0:06:17 > 0:06:20So to understand the butterfly,
0:06:20 > 0:06:25you have to deal with populations moving between continents,
0:06:25 > 0:06:27which is quite exceptional.
0:06:27 > 0:06:29Constanti is piecing together
0:06:29 > 0:06:32why Painted Ladies fly from their breeding grounds here
0:06:32 > 0:06:34to northern Europe each year
0:06:34 > 0:06:36and is getting close to a breakthrough
0:06:36 > 0:06:39in understanding why they make the migration.
0:06:39 > 0:06:43I've come here to find out more and to help where I can,
0:06:43 > 0:06:46using essential butterfly technology.
0:06:46 > 0:06:49I've been issued with some state-of-the-art equipment here.
0:06:53 > 0:06:59And here we have what every good butterfly collector needs -
0:06:59 > 0:07:01a good old-fashioned...
0:07:03 > 0:07:05..butterfly net.
0:07:05 > 0:07:07OK.
0:07:07 > 0:07:10I'm really hoping that we might see some butterflies today.
0:07:10 > 0:07:11Do you think there's any chance?
0:07:11 > 0:07:15The weather is very windy today, so...
0:07:15 > 0:07:19It's not the best time to catch Painted Ladies,
0:07:19 > 0:07:21but there is still an opportunity.
0:07:23 > 0:07:28The odds are against us - not only is it windy, but it's also March.
0:07:28 > 0:07:30Conditions are still good for Painted Ladies,
0:07:30 > 0:07:33but they're already beginning to leave.
0:07:33 > 0:07:37Migration is a risky business, and many will perish along the way.
0:07:37 > 0:07:43If there's somewhere which seems safe and plenty of plants and so on,
0:07:43 > 0:07:45why would they take the risk of moving on
0:07:45 > 0:07:47- when so many of them die?- Yeah...
0:07:47 > 0:07:49- Painted Lady.- Ah!
0:07:53 > 0:07:55Two. Two Painted Ladies.
0:07:55 > 0:07:57- One.- Is it?
0:07:57 > 0:08:00BLEEP, BLEEP, BLEEP!
0:08:00 > 0:08:01There, there... Here.
0:08:03 > 0:08:04Stop, stop, stop.
0:08:15 > 0:08:17It was here. I think it went...
0:08:19 > 0:08:22It was incredibly close. I think I saw it go off that...
0:08:22 > 0:08:26Oh, there it is, there it is. Is that it?
0:08:26 > 0:08:28Got it.
0:08:28 > 0:08:33- Fantastic! You got one. - I got one, yeah.- Brilliant!
0:08:33 > 0:08:36Brilliant!
0:08:36 > 0:08:38So you see that they exist.
0:08:38 > 0:08:40They do exist.
0:08:40 > 0:08:41Can I touch it?
0:08:41 > 0:08:45No, no. The wings not, because the scales will be lost.
0:08:45 > 0:08:50- Oh, right, and you need those. - You only have to touch the body.
0:08:51 > 0:08:54- That's so brilliant that you got one.- Yeah.
0:08:54 > 0:08:57How did you see that? It's so tiny, that one.
0:08:57 > 0:09:01Well, I am always thinking about the Painted Lady,
0:09:01 > 0:09:05so I saw the colour passing by
0:09:05 > 0:09:08and the kind of flight that these butterflies have.
0:09:08 > 0:09:10What are you going to do now?
0:09:10 > 0:09:12I will keep it in this envelope
0:09:12 > 0:09:17and the wings will be used for analysis.
0:09:19 > 0:09:22That really was quite extraordinary
0:09:22 > 0:09:25when Constanti just leapt off cos he'd seen a Painted Lady.
0:09:25 > 0:09:29It reminded me of those great butterfly collectors
0:09:29 > 0:09:31you see in old photos with their nets,
0:09:31 > 0:09:35determined to go anywhere in pursuit of their prey.
0:09:37 > 0:09:41I leave Constanti to it, but I'll be back in the morning.
0:09:41 > 0:09:43We'll be going on a hunt for the Painted Lady's arch enemy
0:09:43 > 0:09:45to gather vital evidence
0:09:45 > 0:09:48which I hope will help us understand the riddle
0:09:48 > 0:09:51of why these butterflies migrate in the first place.
0:09:58 > 0:10:01When I left Morocco, the Painted Ladies were preparing
0:10:01 > 0:10:04to head off on their extraordinary journey,
0:10:04 > 0:10:08but how on earth do they know where to go to once they leave Africa?
0:10:08 > 0:10:11James has been trying to find out.
0:10:11 > 0:10:13So how do our Painted Ladies navigate
0:10:13 > 0:10:15over such incredible distances?
0:10:15 > 0:10:19Scientists here at Rothamsted have been trying to solve that mystery
0:10:19 > 0:10:23and, apparently, all you need is a barrel, some glue,
0:10:23 > 0:10:26a computer and, of course, a Painted Lady butterfly.
0:10:27 > 0:10:31Rebecca Nesbit is a scientist with a passion for Painted Ladies.
0:10:31 > 0:10:34She specialises in butterfly migration,
0:10:34 > 0:10:38and here at Rothamsted, she's part of an elite entomology team.
0:10:38 > 0:10:42For this experiment, first, you have to prepare your butterfly.
0:10:43 > 0:10:47- This one has been in the fridge, so it's...- Nice and cold.- Exactly.
0:10:47 > 0:10:49Sleepy, easy to handle.
0:10:49 > 0:10:52Get it out of the pot.
0:10:52 > 0:10:53And butterflies
0:10:53 > 0:10:55are really obliging.
0:10:55 > 0:10:57If you just touch the outside of their thorax,
0:10:57 > 0:10:59they flick their wings down.
0:11:00 > 0:11:02Oh, yeah.
0:11:02 > 0:11:06And we can very gently trap them on this sponge.
0:11:08 > 0:11:13Just put this mesh over so they're exposed like that.
0:11:15 > 0:11:19This experiment is going to involve attaching a Painted Lady to a wire
0:11:19 > 0:11:21suspended in the barrel.
0:11:24 > 0:11:26We're hoping to show that Painted Ladies
0:11:26 > 0:11:29work out which direction to go when leaving Morocco
0:11:29 > 0:11:31by using the sun as a compass.
0:11:33 > 0:11:35But before this can happen, though,
0:11:35 > 0:11:38you have to do something rather bizarre.
0:11:38 > 0:11:42Next step is to shave...
0:11:44 > 0:11:46- Shave the butterfly. - Shave the butterfly.
0:11:46 > 0:11:49Just really gently rub my finger across it.
0:11:49 > 0:11:52OK, all right, so there's not
0:11:52 > 0:11:54a mini butterfly razor blade, then, that you use?
0:11:54 > 0:11:57Which is what I was expecting, I have to be honest.
0:11:57 > 0:11:58- Sadly not.- It's a bit disappointing,
0:11:58 > 0:12:00but just rub it away.
0:12:00 > 0:12:03You're basically taking the hairs off of the cuticle there,
0:12:03 > 0:12:06just sort of making a smooth surface,
0:12:06 > 0:12:08presumably so you can stick the glue on.
0:12:08 > 0:12:11Exactly. This is just normal contact adhesive.
0:12:11 > 0:12:14- Does it harm the butterfly? - No, not at all.
0:12:17 > 0:12:20A tiny metal rod is glued to the butterfly's back.
0:12:22 > 0:12:24What are we hoping to get out of this experiment?
0:12:24 > 0:12:29What we're hoping to look at is give the butterfly a view of the sky
0:12:29 > 0:12:33and use the sun to find out which direction it's going in,
0:12:33 > 0:12:35so using the sun as a compass.
0:12:36 > 0:12:39Painted Ladies might be travelling vast distances
0:12:39 > 0:12:42by taking cues from the sun's position in the sky
0:12:42 > 0:12:44and combining it with the time of day.
0:12:44 > 0:12:46To prove this, we need to go outside.
0:12:48 > 0:12:50- This is the set-up, then.- Yes.
0:12:50 > 0:12:53So I think the first thing we'll do...
0:12:53 > 0:12:57- I'll just show you the flight simulator.- OK.
0:12:57 > 0:12:58Yeah. Or big white barrel.
0:13:00 > 0:13:01So how does this work, then?
0:13:01 > 0:13:03- That rod we put on the butterfly... - Yeah.
0:13:03 > 0:13:08..that will attach to this really tiny bit of plastic tubing.
0:13:08 > 0:13:10Once we put it on, it is free to turn,
0:13:10 > 0:13:12so the butterfly's flapping
0:13:12 > 0:13:15and it can turn in any direction it likes.
0:13:15 > 0:13:16So it has to be able to see the sun
0:13:16 > 0:13:20- and then will orientate when it sees the sun.- Exactly.
0:13:20 > 0:13:24- It's a bit fiddly.- Really need a steady hand to do this.
0:13:24 > 0:13:26I also need my glasses on.
0:13:27 > 0:13:28Yes!
0:13:30 > 0:13:33So what we need now is to calibrate it,
0:13:33 > 0:13:37so if you could just hold on to the butterfly by the rod
0:13:37 > 0:13:39and come in underneath with a compass.
0:13:39 > 0:13:42- Can I use my phone compass? - Yes, please. Yes, that's perfect.
0:13:42 > 0:13:43I'm holding my mobile phone
0:13:43 > 0:13:46underneath this tethered butterfly as a compass,
0:13:46 > 0:13:49which is a little bit strange - I've never done that before.
0:13:49 > 0:13:51But the idea is we're going to see
0:13:51 > 0:13:54where this butterfly heads in relation to the sun.
0:13:54 > 0:13:57Once I let it go, it should take its lead from the sun
0:13:57 > 0:14:02and fly in a northerly direction, unless it wants to play a bit first.
0:14:02 > 0:14:04Sometimes you can get them to follow a finger.
0:14:04 > 0:14:07That's amazing. It's actually following your finger.
0:14:07 > 0:14:10- Why is it doing that? - I don't really know.
0:14:10 > 0:14:13- Its legs are out. Maybe it is looking to...- To land.
0:14:13 > 0:14:16- Yes.- But, yeah, they often do follow.- Ah!
0:14:16 > 0:14:19Are you sure you haven't trained this one?
0:14:19 > 0:14:21This is actually my pet butterfly!
0:14:23 > 0:14:26With the butterfly ready, it's time to do the experiment.
0:14:26 > 0:14:30So the data's been fed in from the barrel to this box,
0:14:30 > 0:14:31and then what happens?
0:14:31 > 0:14:34The information that that box provides,
0:14:34 > 0:14:38I'm then able to analyse it and plot out the flight path
0:14:38 > 0:14:41that the butterfly would have taken if it wasn't inside the barrel.
0:14:43 > 0:14:46These are some migratory flight paths,
0:14:46 > 0:14:50so you can see that these are relatively straight.
0:14:50 > 0:14:53So how does that tell you how it uses the sun to navigate?
0:14:53 > 0:14:56So what I can do is I can compare a situation like this,
0:14:56 > 0:14:58where it can see the sky,
0:14:58 > 0:15:02with a situation where I've put a lid on the barrel,
0:15:02 > 0:15:04- so the butterfly can't see the sky.- OK.
0:15:04 > 0:15:06And by doing that,
0:15:06 > 0:15:09you can tell whether it's using the sun to navigate by?
0:15:09 > 0:15:11- Exactly.- OK.
0:15:11 > 0:15:15If it can't see the sun, it doesn't know where it's going,
0:15:15 > 0:15:19whereas when it can see the sun, it's got a clear flight path,
0:15:19 > 0:15:20then we know there's a difference.
0:15:22 > 0:15:24The map on the left clearly shows a Painted Lady
0:15:24 > 0:15:27heading in the same general direction,
0:15:27 > 0:15:29whereas by blocking the sun, the map on the right
0:15:29 > 0:15:32shows the Painted Lady moving in random directions.
0:15:34 > 0:15:36So does this experiment definitively prove
0:15:36 > 0:15:39that the Painted Lady butterfly uses the sun to navigate?
0:15:39 > 0:15:42That's certainly what our evidence is suggesting,
0:15:42 > 0:15:46that when they can see the sun, then they know where they're going.
0:15:46 > 0:15:48If you put a lid on the barrel,
0:15:48 > 0:15:52then they aren't going in the right direction you'd expect
0:15:52 > 0:15:55and, actually, they spin around a bit more, they appear more confused.
0:15:57 > 0:16:00What a really neat experiment, demonstrating that the sun
0:16:00 > 0:16:03is like an in-built sat nav for our butterflies -
0:16:03 > 0:16:07an essential piece of kit for our Painted Ladies on the move.
0:16:16 > 0:16:18They're getting very excited
0:16:18 > 0:16:20by your experiment as well, aren't they?
0:16:20 > 0:16:22I mean, it's remarkable, isn't it,
0:16:22 > 0:16:24the way that they manage to use the sun
0:16:24 > 0:16:26to travel these immense distances?
0:16:26 > 0:16:29Yes, it is, and it's such a simple experiment that we did.
0:16:29 > 0:16:32We used a barrel and the sun, essentially, to work it out.
0:16:32 > 0:16:35But I couldn't quite understand from the experiment...
0:16:35 > 0:16:37So they're using the sun for navigation,
0:16:37 > 0:16:40but the position of the sun changes all the time.
0:16:40 > 0:16:42That's right, so as the Earth rotates,
0:16:42 > 0:16:44the sun moves against the horizon.
0:16:44 > 0:16:45We don't actually know
0:16:45 > 0:16:48how these butterflies manage to compensate for that.
0:16:48 > 0:16:50For other butterfly species,
0:16:50 > 0:16:52we know that they have an internal clock.
0:16:52 > 0:16:54I mean, we all have biological clocks.
0:16:54 > 0:16:57- Body clocks.- Body clock, yeah.
0:16:57 > 0:16:59These guys have a body clock as well,
0:16:59 > 0:17:01but it's in their antennae, called a circadian clock.
0:17:01 > 0:17:05Basically, what that allows them to do is to tell what time of day it is
0:17:05 > 0:17:08so they can adjust their flight direction
0:17:08 > 0:17:11based on where the sun is and what time of day it is, essentially.
0:17:11 > 0:17:13- It's very clever.- It is incred...
0:17:13 > 0:17:16You think of these as tiny creatures here,
0:17:16 > 0:17:20and yet they have this highly sophisticated navigation system.
0:17:20 > 0:17:23Yeah, it's a perfect example of evolution
0:17:23 > 0:17:26in terms of how to overcome adverse conditions
0:17:26 > 0:17:28and make the most incredible journey.
0:17:28 > 0:17:30Every single one of these butterflies
0:17:30 > 0:17:33has the ability to do that on its own.
0:17:33 > 0:17:35I think these butterflies' circadian clocks
0:17:35 > 0:17:37are telling them it's breakfast time.
0:17:37 > 0:17:39They're having a bit of orange juice, aren't they?
0:17:39 > 0:17:44Back in March, Painted Ladies were getting ready for their migration.
0:17:44 > 0:17:46In part two of my Moroccan adventure,
0:17:46 > 0:17:49I caught up with them before they left.
0:17:54 > 0:17:56Early morning in the Moroccan desert,
0:17:56 > 0:17:59and the camels are already up.
0:17:59 > 0:18:00It's late March,
0:18:00 > 0:18:03the end of the Painted Lady breeding season
0:18:03 > 0:18:08and the start of their incredible migration.
0:18:08 > 0:18:09It's so windy here,
0:18:09 > 0:18:11and if I'm having to battle against it,
0:18:11 > 0:18:14what on earth is it like for a butterfly?
0:18:14 > 0:18:17Yet that's exactly what the Painted Lady does.
0:18:17 > 0:18:20They fly over this parched desert terrain
0:18:20 > 0:18:23and right over those mountains there
0:18:23 > 0:18:27to make it all the way to Europe and, of course, to Britain.
0:18:32 > 0:18:36I'm on my way to meet up with Constanti Stefanescu again.
0:18:36 > 0:18:39He's the most respected entomologist in his field
0:18:39 > 0:18:42and has had over 100 scientific papers published.
0:18:42 > 0:18:46From environmental impacts on butterflies
0:18:46 > 0:18:49to population declines and Painted Lady migration,
0:18:49 > 0:18:53what he doesn't know about butterflies isn't worth knowing.
0:18:53 > 0:18:58Constanti's latest work is close to revealing ground-breaking science
0:18:58 > 0:19:02that will shed new light on why Painted Ladies migrate.
0:19:03 > 0:19:06He's collecting Painted Lady caterpillars.
0:19:06 > 0:19:08They're under attack from another insect,
0:19:08 > 0:19:11and it's the relationship between them
0:19:11 > 0:19:14that he's particularly keen to investigate.
0:19:14 > 0:19:16'To find a caterpillar,
0:19:16 > 0:19:19'first you have to find the plants they live on.'
0:19:19 > 0:19:22This is one of the very good host plants, isn't it?
0:19:22 > 0:19:26Yeah, look, there are many nests here.
0:19:26 > 0:19:30Host plants provide food for caterpillars.
0:19:30 > 0:19:33Each species of butterfly has a specific plant
0:19:33 > 0:19:36on which they lay their eggs.
0:19:36 > 0:19:39Are there plants that the Painted Lady likes?
0:19:39 > 0:19:44Yeah, in fact, the Painted Lady is one of the few butterflies
0:19:44 > 0:19:47that can use many different kinds of plants,
0:19:47 > 0:19:52even if they prefer these thistles and the mallows.
0:19:52 > 0:19:54What's that caterpillar doing now?
0:19:54 > 0:19:56I see with the binoculars
0:19:56 > 0:20:02that producing some silk and, well, it's building a nest.
0:20:02 > 0:20:04Once built, the nest will form a snug tent
0:20:04 > 0:20:07from which the caterpillar emerges to feed.
0:20:07 > 0:20:10As it grows, so too does the tent.
0:20:10 > 0:20:14I'll just get this little caterpillar here.
0:20:14 > 0:20:16It's clinging on.
0:20:16 > 0:20:18There, is that all right? Not too damaged.
0:20:18 > 0:20:21And there's another much smaller one over here.
0:20:23 > 0:20:24There we go.
0:20:26 > 0:20:31It's astonishing to think that this caterpillar,
0:20:31 > 0:20:36once turned into an adult, could fly all the way to Britain
0:20:36 > 0:20:39and, who knows, even end up in my back garden.
0:20:44 > 0:20:49Collecting Painted Lady caterpillars is easy when you know where to look.
0:20:49 > 0:20:53A far greater challenge for Constanti is what lurks within them.
0:20:53 > 0:20:55He's looking for signs
0:20:55 > 0:21:00that Painted Lady caterpillars have been attacked, but by what?
0:21:03 > 0:21:09So this is a mass of cocoons of the main enemy of the Painted Lady.
0:21:09 > 0:21:11It's a tiny wasp.
0:21:11 > 0:21:14The adult wasp, what it does
0:21:14 > 0:21:19is to search for the larvae of the caterpillar of the Painted Lady
0:21:19 > 0:21:22and lay the eggs inside the body of the caterpillar.
0:21:22 > 0:21:24Once they hatch,
0:21:24 > 0:21:27the wasp larvae begin eating the Painted Lady caterpillar
0:21:27 > 0:21:28from the inside out,
0:21:28 > 0:21:32eventually forming a silky mass around the caterpillar corpse,
0:21:32 > 0:21:35before finally emerging as adult wasps.
0:21:35 > 0:21:42I estimate that maybe 60%, 70% of the caterpillars of the Painted Lady
0:21:42 > 0:21:45are killed by this parasitoid.
0:21:45 > 0:21:47But I can tell when you found that,
0:21:47 > 0:21:50- you were rather excited to find these horrible creatures.- Oh, yeah.
0:21:50 > 0:21:52So what are you going to do with this now?
0:21:52 > 0:21:58I will keep this mass of cocoons inside the vial,
0:21:58 > 0:22:01waiting for the adults to emerge.
0:22:01 > 0:22:02So our butterflies in Morocco
0:22:02 > 0:22:06are under serious attack from a deadly parasite.
0:22:06 > 0:22:08It's the possible link between the parasitic wasps
0:22:08 > 0:22:13and Painted Lady migration that Constanti's investigating.
0:22:13 > 0:22:15One main part of the research
0:22:15 > 0:22:18is to see how many of these caterpillars will die
0:22:18 > 0:22:22because of the parasitise by the wasps,
0:22:22 > 0:22:24and so every night,
0:22:24 > 0:22:28we have to check if some of them have already died or not.
0:22:28 > 0:22:32So, actually, you're quite interested if one's dead.
0:22:32 > 0:22:36Yeah. I hope that some of them will die.
0:22:36 > 0:22:40A curious Constanti is compiling his evidence.
0:22:40 > 0:22:43He'll take the caterpillars home with him to Spain.
0:22:43 > 0:22:45The wasps they might contain
0:22:45 > 0:22:48could be a key component in his migration research.
0:22:50 > 0:22:52I've got to go home soon,
0:22:52 > 0:22:56but I can't leave without catching at least one Painted Lady, can I?
0:22:59 > 0:23:01This morning, I'm on a mission.
0:23:01 > 0:23:03This is my last chance.
0:23:04 > 0:23:06There's one here.
0:23:10 > 0:23:12Yeah.
0:23:12 > 0:23:13Ha! Got one!
0:23:13 > 0:23:17- Here's one.- Oh, I'm so pleased! I'm so pleased.
0:23:17 > 0:23:24Yeah, this butterfly is more easy to catch than a fresh butterfly.
0:23:24 > 0:23:27Oh, come on! It's my first Painted Lady.
0:23:27 > 0:23:29What are you doing here?
0:23:29 > 0:23:33Well, there it is - my first Painted Lady.
0:23:33 > 0:23:35And it's an incredible experience,
0:23:35 > 0:23:38although I'm glad I'm collecting it for science
0:23:38 > 0:23:41rather than just for a collection.
0:23:41 > 0:23:46Painted Ladies are definitely out this morning, and my eye is in.
0:23:46 > 0:23:47Oh, hang on, there it is.
0:23:47 > 0:23:49Oh, yeah. Here's the Painted Lady.
0:23:54 > 0:23:56Oh, no, no...
0:23:58 > 0:24:00- Is it still there?- Yeah.
0:24:00 > 0:24:02- Yeah.- Oh, yeah!
0:24:05 > 0:24:08- OK, your second Painted Lady.- Two!
0:24:08 > 0:24:11That's great. I know my technique was a bit useless, but I got it.
0:24:11 > 0:24:13I did get it. Number two.
0:24:13 > 0:24:18Number two, yeah. But you see again, this is a very, very old butterfly.
0:24:18 > 0:24:23Show a bit of gratitude! Stop saying it's old and rubbish.
0:24:23 > 0:24:26Be pleased I'm doing your work for you!
0:24:26 > 0:24:28- For free. - Thank you. Thank you so much.
0:24:28 > 0:24:31- It's been a really good day, no? - Yeah.
0:24:31 > 0:24:35The adults... I think it's time for a tagine, no?
0:24:35 > 0:24:37Tagine - now you're talking.
0:24:37 > 0:24:41We can celebrate the capture of the Painted Ladies with a nice tagine.
0:24:43 > 0:24:47Constanti managed to collect over 100 caterpillars in Morocco
0:24:47 > 0:24:50which, depending on how many develop into butterflies
0:24:50 > 0:24:52and how many are killed by the wasps,
0:24:52 > 0:24:54could shed new light on understanding
0:24:54 > 0:24:56the Painted Lady migration.
0:24:58 > 0:25:02Scientists like Constanti, at the forefront of lepidoptery,
0:25:02 > 0:25:06rely on centuries of research by enthusiastic amateurs.
0:25:06 > 0:25:08Many of their specimens
0:25:08 > 0:25:11are now in the Natural History Museum in London,
0:25:11 > 0:25:15home to the largest collection of Painted Ladies in the world.
0:25:15 > 0:25:18This is my very own private night at the museum,
0:25:18 > 0:25:22with the echoing walls now all the crowds have gone.
0:25:22 > 0:25:27You normally think of dinosaurs like Dippy at the Natural History Museum
0:25:27 > 0:25:32but, actually, there are more than 30 million insect specimens,
0:25:32 > 0:25:35as well as a whole load of world-renowned experts,
0:25:35 > 0:25:38so where better a place to come than here
0:25:38 > 0:25:40to find out more about Painted Ladies,
0:25:40 > 0:25:43those incredible flying machines?
0:25:43 > 0:25:46Well, I'm really looking forward to being able to find out more
0:25:46 > 0:25:50about the kind of detailed anatomy of the Painted Lady.
0:25:51 > 0:25:54Dr Blanca Huertas is the senior curator
0:25:54 > 0:25:56of the museum's butterfly collection.
0:25:56 > 0:25:59There are over four million butterflies here,
0:25:59 > 0:26:02including Painted Ladies from around the globe.
0:26:04 > 0:26:06So is where they all are?
0:26:06 > 0:26:08Yeah, this is the corner
0:26:08 > 0:26:11in the world's biggest collection of butterflies
0:26:11 > 0:26:14where we have the Painted Ladies.
0:26:14 > 0:26:17And how many Painted Ladies have you got here?
0:26:17 > 0:26:20We have probably about 3,000 specimens.
0:26:20 > 0:26:24We have specimens from all over the world in here.
0:26:24 > 0:26:28Painted Ladies are found in more countries than any other butterfly,
0:26:28 > 0:26:31making them also one of the most successful.
0:26:31 > 0:26:33Just in these six, seven boxes,
0:26:33 > 0:26:36we have specimens from around 40 countries.
0:26:36 > 0:26:38We've got things from Turkey,
0:26:38 > 0:26:42we've got things from Morocco, Sri Lanka...everywhere.
0:26:42 > 0:26:45And what kind of time span, then, do you have?
0:26:45 > 0:26:50We've got collections back into the early 1800s in here.
0:26:50 > 0:26:52Do you notice differences in the patterns?
0:26:52 > 0:26:55Yeah, that's why we have a long series of butterflies.
0:26:55 > 0:26:59Some have differences, say, not just on the upper side,
0:26:59 > 0:27:01but also if you look into the underside.
0:27:01 > 0:27:03They're very distinctive.
0:27:03 > 0:27:06They're very different to how they actually look in the upper sides.
0:27:06 > 0:27:11The rich colours are used for courtship and camouflage.
0:27:11 > 0:27:14Open wings display your wares to other Painted Ladies.
0:27:14 > 0:27:17Closed, they blend in with the background
0:27:17 > 0:27:21to help them avoid being eaten by predators like birds.
0:27:21 > 0:27:22Interestingly enough,
0:27:22 > 0:27:25the females are much bigger, and also kind of faded.
0:27:25 > 0:27:28So sometimes you see lots of butterflies,
0:27:28 > 0:27:31kind of, really bright colours, and they are only males.
0:27:31 > 0:27:34The males are the ones who are really, really bright.
0:27:34 > 0:27:37The females are a little bit more dull.
0:27:37 > 0:27:38More dull, more faded?
0:27:38 > 0:27:42Yeah. It's an expensive business, in evolutionary speaking,
0:27:42 > 0:27:45producing colour with all of these pigments.
0:27:45 > 0:27:47It implies a lot of energy.
0:27:47 > 0:27:49So the females need that energy in other things,
0:27:49 > 0:27:53like giving birth to the next butterflies,
0:27:53 > 0:27:54to the next generation.
0:27:54 > 0:27:56So the males still can afford it,
0:27:56 > 0:27:58but the females are very careful how they spend their energy.
0:27:58 > 0:28:02So the males are expending all their energy looking good,
0:28:02 > 0:28:05and the females are back at base, breeding?
0:28:05 > 0:28:06Absolutely.
0:28:06 > 0:28:09And if they don't do that, they don't succeed finding a mate.
0:28:09 > 0:28:11The males are the ones showing off,
0:28:11 > 0:28:13and the females are usually the ones
0:28:13 > 0:28:17who select those good-looking males in butterflies.
0:28:19 > 0:28:23Our fascination with butterflies goes back centuries.
0:28:23 > 0:28:26They were valuable and coveted treasures back in the day.
0:28:27 > 0:28:30Dr Hans Sloane was an Irish-born scientist
0:28:30 > 0:28:33and keen collector in the 1600s.
0:28:33 > 0:28:36He amassed one of the greatest collections
0:28:36 > 0:28:38of plants and animals of his time.
0:28:40 > 0:28:43His curiosities, as they were known then,
0:28:43 > 0:28:45are the founding core of the museum's collections.
0:28:47 > 0:28:50We're now in the historical collections.
0:28:50 > 0:28:52What an historical collection, as well.
0:28:52 > 0:28:54These incredibly big books.
0:28:54 > 0:28:56The crown jewels, actually!
0:28:56 > 0:29:01We've got the oldest specimens of plants preserved in here.
0:29:01 > 0:29:05But not only the oldest specimens of plants
0:29:05 > 0:29:08where I've brought you today, because we have in here,
0:29:08 > 0:29:12pressed in the herbarium sheets of Hans Sloane,
0:29:12 > 0:29:15we've got the oldest Painted Lady ever collected and pressed
0:29:15 > 0:29:18and preserved here in the Natural History Museum.
0:29:18 > 0:29:20The oldest Painted Lady?
0:29:20 > 0:29:22Yes, we're going back into the 1600s.
0:29:22 > 0:29:25So even as his snap in time with the plants,
0:29:25 > 0:29:27this butterfly was flying around,
0:29:27 > 0:29:29and we're going to see it in a minute.
0:29:29 > 0:29:32And this is part of this incredible historical collection
0:29:32 > 0:29:33which Hans Sloane started?
0:29:33 > 0:29:36Yes, that was collected by himself
0:29:36 > 0:29:41and preserved by the Reverend Adam Buddle.
0:29:41 > 0:29:45OK, let's go and see what Adam Buddle had in his scrapbook.
0:29:47 > 0:29:50Adam Buddle was a botanist in the 1600s.
0:29:50 > 0:29:53Amateur collectors were rife in those days.
0:29:53 > 0:29:56His vast knowledge of plants meant his collections
0:29:56 > 0:29:59were more respected and relevant than most.
0:29:59 > 0:30:01At the same time the naturalists were collecting plants,
0:30:01 > 0:30:04they also pressed some butterflies in here.
0:30:04 > 0:30:07This one in particular is a very, very old specimen.
0:30:07 > 0:30:10That's amazing. How old is that?
0:30:10 > 0:30:15This was collected back in the 1600s, late 1600s.
0:30:15 > 0:30:18This is the oldest Painted Lady we have knowledge of
0:30:18 > 0:30:21and it's in here in the Natural History Museum collections.
0:30:21 > 0:30:23And did you know it was here?
0:30:23 > 0:30:26It was kind of a recent discovery for us
0:30:26 > 0:30:28and it's very exciting to show you.
0:30:28 > 0:30:30I can see that it's a Painted Lady,
0:30:30 > 0:30:34and it's been pressed in the same way that we'd press wildflowers.
0:30:34 > 0:30:40Yeah. Pre-1700s, that was the method to preserve specimens.
0:30:40 > 0:30:41Collected flowers and plants
0:30:41 > 0:30:44were pressed onto book pages known as herbarium sheets.
0:30:44 > 0:30:48Butterflies were preserved with the flowers they feed on,
0:30:48 > 0:30:50a practice that's still done today.
0:30:51 > 0:30:55Look here. We have it written in quite shaky handwriting -
0:30:55 > 0:30:56"The Painted Lady".
0:30:56 > 0:31:01They have a common name. It's still in use after 300 years.
0:31:01 > 0:31:04I just love looking at the detail of all of this.
0:31:04 > 0:31:06It's almost like a work of art, this.
0:31:06 > 0:31:08It's so beautiful,
0:31:08 > 0:31:11the way he's placed the butterflies in amongst the grasses.
0:31:11 > 0:31:16That was preserved by Reverend Adam Buddle.
0:31:16 > 0:31:19You probably have heard about the butterfly bushes, the buddleia.
0:31:19 > 0:31:22- Yes. - That's where the name came from.
0:31:22 > 0:31:27Over many years, he compiled a definitive English plant guide
0:31:27 > 0:31:28that was never published.
0:31:28 > 0:31:31The original manuscript is preserved here.
0:31:31 > 0:31:35In later years, the well-known buddleia plant, or butterfly bush,
0:31:35 > 0:31:37was named in his honour.
0:31:37 > 0:31:40Do you know, all the time that I've talked about buddleia,
0:31:40 > 0:31:41I've got buddleia in my garden,
0:31:41 > 0:31:43I didn't realise it came from a person,
0:31:43 > 0:31:47the person who, all those years ago, collected these butterflies.
0:31:47 > 0:31:48A great naturalist.
0:31:48 > 0:31:51As you see, lots of care, lots of notes and detail
0:31:51 > 0:31:54on this collection - well preserved.
0:31:54 > 0:31:56So a very important snap in time?
0:31:56 > 0:31:59Absolutely. Probably the only one, really.
0:32:01 > 0:32:03It really has been so interesting
0:32:03 > 0:32:07to come behind the scenes at the Natural History Museum,
0:32:07 > 0:32:11where they've been studying butterflies for generations.
0:32:11 > 0:32:16You know, insects are the most successful animals on the planet,
0:32:16 > 0:32:19and it's easy to see why Painted Ladies fall into that category.
0:32:23 > 0:32:24Back in March,
0:32:24 > 0:32:27our Painted Ladies had been breeding in Morocco in large numbers
0:32:27 > 0:32:32ahead of travelling across Europe on their epic migration.
0:32:32 > 0:32:33The life cycle of the butterfly
0:32:33 > 0:32:36is one of the most fascinating in the natural world.
0:32:38 > 0:32:42As Painted Ladies only live for up to three weeks, they breed quickly.
0:32:45 > 0:32:48When a male finds a female, he has to win her affection.
0:32:49 > 0:32:51To do this, he uses perfume.
0:32:53 > 0:32:55Chemicals called pheromones
0:32:55 > 0:32:58are intoxicating to females at close range.
0:33:00 > 0:33:02If she likes it, they settle down to mate.
0:33:11 > 0:33:13They stay locked together for up to an hour,
0:33:13 > 0:33:15sunbathing at every opportunity.
0:33:21 > 0:33:23Eggs no bigger than a pinhead
0:33:23 > 0:33:26are laid on plants the caterpillars feed on.
0:33:26 > 0:33:29Jewel-encrusted thistles glisten for five days
0:33:29 > 0:33:31before bursting into life.
0:33:34 > 0:33:37Caterpillars gorge themselves from the moment they hatch,
0:33:37 > 0:33:39and begin to grow,
0:33:39 > 0:33:42shedding their skin five times before reaching full size.
0:33:45 > 0:33:46In just ten days,
0:33:46 > 0:33:51the caterpillar is a colossal 100 times bigger than when it hatched.
0:33:53 > 0:33:58Suspended on a silk pad, it splits its skin one last time,
0:33:58 > 0:34:01revealing a case-like chrysalis or pupa.
0:34:01 > 0:34:03Inside the chrysalis,
0:34:03 > 0:34:06the caterpillar reduces itself to a DNA soup,
0:34:06 > 0:34:09reconstructing into something else entirely.
0:34:11 > 0:34:14Two weeks later, a Painted Lady butterfly emerges
0:34:14 > 0:34:18and the cycle starts all over again.
0:34:27 > 0:34:30We're following this year's Painted Lady butterfly migration,
0:34:30 > 0:34:33and our communications centre is buzzing.
0:34:37 > 0:34:41Piece by piece, scientific experiments,
0:34:41 > 0:34:44eyewitness accounts and the world's leading experts
0:34:44 > 0:34:48are helping us unravel the mysteries of an extraordinary journey.
0:34:49 > 0:34:51We know it began in Morocco
0:34:51 > 0:34:54at the end of the winter breeding season in March.
0:34:54 > 0:34:59Our Painted Ladies then touched down in Catalonia, in Spain, to refuel.
0:34:59 > 0:35:01And this is where I caught up with them next.
0:35:10 > 0:35:11To get to Spain,
0:35:11 > 0:35:16our Painted Ladies have had to overcome extreme desert conditions
0:35:16 > 0:35:19and to climb to incredible heights,
0:35:19 > 0:35:25navigating mountains as high as 13,500 feet.
0:35:25 > 0:35:28Many will have died, the voyage taking its toll,
0:35:28 > 0:35:30or been eaten by predators.
0:35:31 > 0:35:36An exhausted Painted Lady is easy pickings for a hungry frog.
0:35:37 > 0:35:40Those that do make it this far are rewarded with better conditions.
0:35:42 > 0:35:44These beautiful olive groves
0:35:44 > 0:35:47just brimming everywhere you look with spring wildflowers.
0:35:47 > 0:35:50I mean, it couldn't be further away, could it,
0:35:50 > 0:35:54from the mountainous, rocky deserts of Morocco?
0:35:54 > 0:35:59But Catalonia is the first stop for many of the Painted Ladies we saw.
0:35:59 > 0:36:03It's 1,500km from their breeding ground
0:36:03 > 0:36:07and they're still only halfway from their final destination.
0:36:10 > 0:36:12I met up with Constanti
0:36:12 > 0:36:16at the Granollers Natural History Museum in Catalonia.
0:36:16 > 0:36:20He's been studying the specimens I helped him collect in Morocco
0:36:20 > 0:36:22and I'm keen to discover what he's found out,
0:36:22 > 0:36:25but not before indulging my passion for all things butterflies
0:36:25 > 0:36:27with him first.
0:36:27 > 0:36:30I love these old illustrations.
0:36:30 > 0:36:34They're incredible, aren't they, the detail on some of these?
0:36:34 > 0:36:36Yeah, they are good indeed.
0:36:36 > 0:36:38Painted Lady, Peacock.
0:36:38 > 0:36:42Do you think it is there's something about the beauty of butterflies
0:36:42 > 0:36:44that makes people want to study them?
0:36:44 > 0:36:46Oh, yeah, of course.
0:36:46 > 0:36:51There are many more people that are attracted by butterflies
0:36:51 > 0:36:54than by beetles, for example.
0:36:54 > 0:36:57And you've got quite a few collections here in the museum?
0:36:57 > 0:36:59Yeah, and one of these collections
0:36:59 > 0:37:02is my own collection that I did when I was...
0:37:02 > 0:37:05- Is this yours? - Yeah, this is mine.
0:37:05 > 0:37:08- Here you are.- Ah, gosh.
0:37:08 > 0:37:10And, well,
0:37:10 > 0:37:14it's very useful to start a butterfly collection
0:37:14 > 0:37:17to learn to distinguish the species.
0:37:17 > 0:37:19Well, even I can get some of these.
0:37:19 > 0:37:21OK, that's Peacock?
0:37:21 > 0:37:24- That's Peacock. - Red Admiral.- Red Admiral.
0:37:24 > 0:37:26OK, and if I haven't got the Painted Lady by now,
0:37:26 > 0:37:29- you'd be despairing of me, wouldn't you?- Yeah.
0:37:31 > 0:37:35Around the world, it's not Constanti's beloved Painted Ladies
0:37:35 > 0:37:36that get all the attention.
0:37:36 > 0:37:38Until recently,
0:37:38 > 0:37:42it was thought the Monarch carried out the longest butterfly migration.
0:37:43 > 0:37:47Travelling 3,500km from the US to Mexico,
0:37:47 > 0:37:51it often returns to the same trees where its ancestors were born.
0:37:53 > 0:37:57Thousands form a spectacular butterfly blanket in the process,
0:37:57 > 0:38:00which I've seen myself in the Mexican forest.
0:38:00 > 0:38:03The Monarch might be a headline-grabbing superstar,
0:38:03 > 0:38:05but it's not a patch on the Painted Lady.
0:38:08 > 0:38:11I'm amazed by how much material there is
0:38:11 > 0:38:13about the Monarch butterfly,
0:38:13 > 0:38:17but really comparatively little about the Painted Lady.
0:38:17 > 0:38:19Well, I am quite envious
0:38:19 > 0:38:24about how much has been done, and is being done, on the Monarch
0:38:24 > 0:38:28and the little research that is being done on the Painted Lady.
0:38:28 > 0:38:30But on the other hand,
0:38:30 > 0:38:33it means that we still have many, many things to explore
0:38:33 > 0:38:35on the Painted Lady, which is nice.
0:38:35 > 0:38:38But, actually, the Painted Lady is the champion, isn't it?
0:38:38 > 0:38:40I think so. I think...
0:38:40 > 0:38:43Well, I know for sure
0:38:43 > 0:38:49the Painted Lady can fly more than 4,000km
0:38:49 > 0:38:53in the whole cycle of migration,
0:38:53 > 0:39:02and the Monarch can do as much as 3,500km,
0:39:02 > 0:39:06so at least the Painted Lady can win the Monarch in this sense.
0:39:07 > 0:39:11Constanti is trying to solve a migration mystery
0:39:11 > 0:39:14that's occupied his work for the last ten years.
0:39:14 > 0:39:16After numerous field trips to Morocco,
0:39:16 > 0:39:18collecting live caterpillars,
0:39:18 > 0:39:22he's slowly unravelling the effect a sinister parasite might have
0:39:22 > 0:39:24on the Painted Lady migration.
0:39:24 > 0:39:27So all those specimens that you collected
0:39:27 > 0:39:30in the heat of the Moroccan desert, you've brought them back here,
0:39:30 > 0:39:32and what have you been doing with them?
0:39:32 > 0:39:36I brought back all these larvae until they pupate
0:39:36 > 0:39:41or until they die because they were attacked by the wasps.
0:39:41 > 0:39:44I recognise the cocoon from the caterpillars
0:39:44 > 0:39:47that you showed me in Morocco.
0:39:47 > 0:39:50And what's emerged from that white mass?
0:39:50 > 0:39:54Well, inside this mass, there are many cocoons.
0:39:54 > 0:39:56Very small cocoons.
0:39:56 > 0:40:00And from each cocoon will emerge one of these wasps.
0:40:00 > 0:40:05These are sisters that come from a single female
0:40:05 > 0:40:08that lay the eggs inside the caterpillar.
0:40:08 > 0:40:13Are you telling me that all these wasps came from one caterpillar?
0:40:13 > 0:40:15From one caterpillar, yeah.
0:40:15 > 0:40:21- Gosh.- Maybe there can be between 50, 60, 70, depending.
0:40:21 > 0:40:23It's almost as if each one of these
0:40:23 > 0:40:26is then able to lay 50 eggs in a caterpillar.
0:40:26 > 0:40:29I mean, they could wipe out the Painted Lady, couldn't they?
0:40:29 > 0:40:32Yeah. In Morocco, we have seen
0:40:32 > 0:40:35that most of the populations of Cotesia, of these wasps,
0:40:35 > 0:40:39are composed only by females.
0:40:39 > 0:40:41They can reproduce without the males.
0:40:41 > 0:40:46So every single wasp can parasitise, can attack,
0:40:46 > 0:40:50and lay eggs in a new Painted Lady caterpillar,
0:40:50 > 0:40:53so the risk is terribly high.
0:40:54 > 0:40:56A good Painted Lady breeding season
0:40:56 > 0:41:01inevitably becomes an even better one for the parasitic wasps.
0:41:01 > 0:41:04Constanti believes the wasps have a key role to play
0:41:04 > 0:41:06in Painted Lady migration.
0:41:06 > 0:41:09It won't be long before he can finally reveal his findings.
0:41:11 > 0:41:15Outside in Catalonia, the Ladies are already here.
0:41:16 > 0:41:19The ones who managed to escape the parasitic wasps
0:41:19 > 0:41:21are enjoying the Spanish sun.
0:41:21 > 0:41:23So why is it you think
0:41:23 > 0:41:26that the Painted Lady has come to places like this?
0:41:26 > 0:41:30Well, because here, they find exactly what they need
0:41:30 > 0:41:34to have a big success for reproduction.
0:41:34 > 0:41:37So you see that everything is green.
0:41:37 > 0:41:42There are flowers everywhere, there is nectar for the adults,
0:41:42 > 0:41:44there are food plants everywhere.
0:41:44 > 0:41:48But this lasts only a short period.
0:41:48 > 0:41:53So the next generation has to move to the north,
0:41:53 > 0:41:58to track the same situation in central Europe or northern Europe.
0:41:58 > 0:42:02So it's the strategy of this long-range migrant
0:42:02 > 0:42:03which is the Painted Lady.
0:42:05 > 0:42:09So not all Painted Ladies fly to Britain in one go.
0:42:09 > 0:42:13Many stop over somewhere like this to feed and breed,
0:42:13 > 0:42:15their offspring emerging hard-wired
0:42:15 > 0:42:18to continue migrating to Britain and beyond.
0:42:18 > 0:42:20It's a relay race,
0:42:20 > 0:42:24with one generation passing the baton to the next, and so on.
0:42:24 > 0:42:28Some, however, emerge from a chrysalis in Spain
0:42:28 > 0:42:32and don't migrate any further at all, choosing instead to stay
0:42:32 > 0:42:35and spend their short three-week life breeding,
0:42:35 > 0:42:37while food is abundant.
0:42:38 > 0:42:41Their main food plant, thistles, are seasonal.
0:42:41 > 0:42:44As they die off in one country, they bloom in another.
0:42:44 > 0:42:47So it makes sense for some Painted Ladies
0:42:47 > 0:42:49to migrate and follow them.
0:42:49 > 0:42:52Much of what Constanti had shown me in Spain
0:42:52 > 0:42:55involved the Painted Lady's arch enemy wasp.
0:42:55 > 0:42:58What he'd kept from me was worth the wait.
0:42:58 > 0:43:01So here, I have some of the butterflies
0:43:01 > 0:43:06that I raised from the caterpillars that we collected from Morocco.
0:43:06 > 0:43:09- So these are all... Right, OK.- OK?
0:43:11 > 0:43:14One of the caterpillars Constanti brought back from Morocco
0:43:14 > 0:43:17didn't fall foul of the Cotesia wasps
0:43:17 > 0:43:19and instead went through its full transformation
0:43:19 > 0:43:22into a butterfly in his office.
0:43:22 > 0:43:24- Oh, yes, I can see them.- Yeah. - The legs are moving.
0:43:24 > 0:43:29That's a male, so we can release this male at the hilltop.
0:43:29 > 0:43:32- Oh, great, OK. - Probably he will enjoy the place.
0:43:32 > 0:43:37I'm very nervous about doing this, because they're so delicate.
0:43:37 > 0:43:39OK, all right. So, just...
0:43:39 > 0:43:40OK, like this.
0:43:40 > 0:43:42Just here, yeah?
0:43:42 > 0:43:43- Yeah?- OK.
0:43:43 > 0:43:46OK, that's incredible - this butterfly,
0:43:46 > 0:43:49which came from a caterpillar we picked up in Morocco,
0:43:49 > 0:43:53has never flown before, and we're just going to let it go.
0:43:53 > 0:43:55Off you go. Off you go.
0:43:55 > 0:43:57Oh, look. He needs to warm his wings up a little bit first.
0:43:57 > 0:44:01- Do you think?- Well, I think he is more or less ready.
0:44:01 > 0:44:04OK, I'm going to let him... You take your time.
0:44:04 > 0:44:06A virgin flight is a big deal.
0:44:09 > 0:44:11It's really fluttering.
0:44:13 > 0:44:15- Come on.- Oh!
0:44:15 > 0:44:17There he goes!
0:44:17 > 0:44:20- He's doing quite well, huh? - Not bad for a first flight.
0:44:21 > 0:44:23A hesitant start, maybe,
0:44:23 > 0:44:26but this butterfly will be migrating north to the UK
0:44:26 > 0:44:29alongside the others within days -
0:44:29 > 0:44:32unless, of course, it decides to stay and breed
0:44:32 > 0:44:34for its short life instead.
0:44:41 > 0:44:45So why are some Painted Ladies driven to migrate and others not?
0:44:45 > 0:44:49James is getting exclusive access behind the scenes
0:44:49 > 0:44:52here at Rothamsted to find out.
0:44:52 > 0:44:54I've been given special permission
0:44:54 > 0:44:57to get inside this high-security facility here at Rothamsted
0:44:57 > 0:45:00to find out some of the latest cutting-edge research
0:45:00 > 0:45:02on insect migration.
0:45:02 > 0:45:03I feel quite privileged.
0:45:08 > 0:45:10This is pretty awesome.
0:45:10 > 0:45:12It's like being in a spaceship in a sci-fi movie
0:45:12 > 0:45:13or something like that.
0:45:13 > 0:45:15It's also a little bit spooky.
0:45:15 > 0:45:18But I believe this is where the magic happens.
0:45:20 > 0:45:23Here, they're studying migratory moths
0:45:23 > 0:45:26to understand what makes some insects of the same species migrate
0:45:26 > 0:45:28and others not.
0:45:28 > 0:45:31The results should apply to migrating butterflies as well.
0:45:33 > 0:45:36What on earth is going on in this experiment?
0:45:36 > 0:45:38Well, we use a number of techniques in our lab
0:45:38 > 0:45:39to study insect migration.
0:45:39 > 0:45:41And these are our roundabout-style
0:45:41 > 0:45:43tethered flight mills.
0:45:43 > 0:45:46OK, so roundabouts for moths?
0:45:46 > 0:45:48That's right, yes. So, basically, we use this technique
0:45:48 > 0:45:52to investigate the flight capability of different individuals
0:45:52 > 0:45:53of the same species,
0:45:53 > 0:45:55using this technique
0:45:55 > 0:45:57to identify good flyers and poor flyers
0:45:57 > 0:46:01so we can try to understand the genetic control of migration.
0:46:02 > 0:46:04The moths on the roundabouts are flying on their own accord.
0:46:04 > 0:46:07It's their natural flight driving them
0:46:07 > 0:46:10and their every move is being measured.
0:46:10 > 0:46:13OK, so how do you define a good flyer and a poor flyer?
0:46:13 > 0:46:15Is it all to do with how far they fly or...?
0:46:15 > 0:46:17We place the moth onto this roundabout
0:46:17 > 0:46:20and then we just allow the moths to fly overnight
0:46:20 > 0:46:22and then those individuals which have flown a long way,
0:46:22 > 0:46:25which might be 30km in a single night,
0:46:25 > 0:46:27we can put into one category,
0:46:27 > 0:46:30and then we might have others that only fly a few hundred metres.
0:46:30 > 0:46:31And why do they do that?
0:46:31 > 0:46:34Why do you have some long-haul and some short-haul flyers?
0:46:34 > 0:46:37Some individuals can be highly migratory
0:46:37 > 0:46:38and others hardly move at all.
0:46:38 > 0:46:41And they do this in response to different conditions
0:46:41 > 0:46:45- that promote migration or not, as the case may be.- OK.
0:46:45 > 0:46:47But something in the environment or something can change
0:46:47 > 0:46:50and trigger them to become a long-haul flyer?
0:46:50 > 0:46:51That is exactly what happens.
0:46:51 > 0:46:54And so it might be the environmental conditions,
0:46:54 > 0:46:57the weather, it might be the quality of the host crops
0:46:57 > 0:46:58that they're feeding on.
0:46:58 > 0:47:00That can turn them into a migratory
0:47:00 > 0:47:02or it can turn off the migratory genes.
0:47:02 > 0:47:05What are those genes actually doing physically to the insect?
0:47:05 > 0:47:06How do they help with the migration?
0:47:06 > 0:47:09Well, there's a whole number of genes that are being overexpressed,
0:47:09 > 0:47:13but some of them are evolved with the availability of flight fuel
0:47:13 > 0:47:15which, in these insects, is body fat.
0:47:15 > 0:47:19So a number of genes are associated with turning fat into a fuel
0:47:19 > 0:47:20that they can use.
0:47:20 > 0:47:23There are also genes which are associated
0:47:23 > 0:47:27with the production of strong, very active flight muscles.
0:47:27 > 0:47:31And so, again, those long flyers, they have the strongest muscles.
0:47:31 > 0:47:35The genes associated with those are turned up to maximum, if you like.
0:47:35 > 0:47:37Wow. Does this apply to other insects?
0:47:37 > 0:47:41Whatever we learn here would be perfectly transferable
0:47:41 > 0:47:43to all butterflies and moths that migrate
0:47:43 > 0:47:46and so it would be relevant to the Painted Lady story.
0:47:46 > 0:47:48So, what this research is revealing
0:47:48 > 0:47:50is that variations in environmental conditions
0:47:50 > 0:47:54appear to switch certain migratory genes on or off.
0:47:54 > 0:47:56Some are fatter, some are fitter,
0:47:56 > 0:47:59some develop bigger flight muscles, and so on.
0:47:59 > 0:48:01Fatter ones with stronger muscles
0:48:01 > 0:48:04are likely to continue migrating to the next country,
0:48:04 > 0:48:08while others are better equipped to stay in one place and breed.
0:48:16 > 0:48:20We are monitoring the 2016 migration at Rothamsted,
0:48:20 > 0:48:24and know that Painted Ladies left Morocco in March.
0:48:24 > 0:48:26By April, they were breeding in Catalonia.
0:48:26 > 0:48:27I came back from there
0:48:27 > 0:48:30expecting them to be navigating through France
0:48:30 > 0:48:32and hitting our shores in early May.
0:48:33 > 0:48:36May came, but not many Painted Ladies.
0:48:39 > 0:48:42Brutal weather in northern Europe earlier this year
0:48:42 > 0:48:44hit them from all sides.
0:48:44 > 0:48:46So it's no surprise, then,
0:48:46 > 0:48:49that the class of 2016 is late arriving.
0:48:51 > 0:48:53In May and early summer,
0:48:53 > 0:48:58northern Europe had its highest rainfall for over 100 years.
0:48:58 > 0:49:02Rising river levels threatened to decimate towns in Germany,
0:49:02 > 0:49:06Paris flooded and the UK had one of its wettest Junes ever.
0:49:06 > 0:49:10An average Painted Lady weighs 200mg.
0:49:10 > 0:49:13Large raindrops can weigh more than 70mg.
0:49:13 > 0:49:16So flying through rain is virtually impossible.
0:49:16 > 0:49:19Added to that, butterflies need to warm up
0:49:19 > 0:49:21in the sun to fly efficiently,
0:49:21 > 0:49:24so bad weather is bad news for Painted Ladies.
0:49:36 > 0:49:39Back at Rothamsted, the Painted Ladies in our hub
0:49:39 > 0:49:42are making the most of what we put out for them.
0:49:42 > 0:49:46The butterflies love the sugar that they get from the oranges,
0:49:46 > 0:49:48and that's one reason why they migrate,
0:49:48 > 0:49:50why they go from Morocco to Spain,
0:49:50 > 0:49:53is because the food plants dry up in one country
0:49:53 > 0:49:57and they need to move on to find fresh plants,
0:49:57 > 0:49:59like these here, the buddleia,
0:49:59 > 0:50:02which you may have in your garden, that the butterflies enjoy so much.
0:50:02 > 0:50:06But not all of them travel up through the western Mediterranean.
0:50:06 > 0:50:09Some head east instead, as we are going to see.
0:50:11 > 0:50:14When Painted Ladies leave Morocco,
0:50:14 > 0:50:16they don't all head one way to northern Europe -
0:50:16 > 0:50:20some embark on a route to eastern Europe instead.
0:50:20 > 0:50:24Each year, the different routes have varying degrees of success.
0:50:24 > 0:50:27Through April and May this year,
0:50:27 > 0:50:31great numbers descended on Corfu and Crete via the eastern route,
0:50:31 > 0:50:34but comparatively few arrived in northern Spain and Britain,
0:50:34 > 0:50:36due to bad weather.
0:50:36 > 0:50:39By expanding their distribution across different routes,
0:50:39 > 0:50:42the butterflies breed successfully in enough countries
0:50:42 > 0:50:44to keep their overall numbers up.
0:50:49 > 0:50:53While some emerge from their cocoons and continue migrating,
0:50:53 > 0:50:56others emerge and do not travel on,
0:50:56 > 0:50:59staying instead to breed a further generation.
0:50:59 > 0:51:02That is why we see more and more Painted Ladies
0:51:02 > 0:51:04as the summer progresses.
0:51:07 > 0:51:09In the communications centre,
0:51:09 > 0:51:13James has been mapping the progress of our Painted Lady migration
0:51:13 > 0:51:14as it has unfolded.
0:51:14 > 0:51:16What have you been looking at?
0:51:16 > 0:51:18Well, I'm just mapping out the routes, actually,
0:51:18 > 0:51:20of some of these butterflies.
0:51:20 > 0:51:23You started off here, didn't you, in Morocco?
0:51:23 > 0:51:26South of Marrakech, really near to the Sahara desert.
0:51:26 > 0:51:28Of course, they can start off pretty much anywhere
0:51:28 > 0:51:34across this Northern African belt, here, and sort of head northwards.
0:51:34 > 0:51:36Let's draw this out. So, you started about here
0:51:36 > 0:51:39and then you moved up to Catalonia, didn't you?
0:51:39 > 0:51:41Yes, it's the kind of north of Spain.
0:51:41 > 0:51:43Imagine being the size of a butterfly
0:51:43 > 0:51:44and having to fly that far.
0:51:44 > 0:51:46You'd think it would take a long time, but actually,
0:51:46 > 0:51:49scientists have modelled it and they reckon that it could take
0:51:49 > 0:51:51as little as 20 to 36 hours.
0:51:51 > 0:51:53That's with a tailwind, obviously,
0:51:53 > 0:51:55and then flying at an average of 15km per hour.
0:51:55 > 0:51:58And then they head on, they just carry the drive northwards?
0:51:58 > 0:52:01That's right. So, the ones that you saw in Catalonia
0:52:01 > 0:52:05probably will make their way, or already have made their way,
0:52:05 > 0:52:07or are starting to make their way, up here.
0:52:07 > 0:52:09But over here, on the other hand -
0:52:09 > 0:52:12let's do this in another colour, cos it seems to be a second route,
0:52:12 > 0:52:14certainly with the sightings -
0:52:14 > 0:52:17the butterflies seem to be heading up perhaps from Libya, here,
0:52:17 > 0:52:20maybe the coast of Egypt, up to Crete.
0:52:20 > 0:52:23So lots of sightings in Crete and other parts of Greece, as well.
0:52:23 > 0:52:25So, this seems to be a bit of a hot spot this year
0:52:25 > 0:52:27with our butterfly spotters.
0:52:27 > 0:52:31I love the idea that there are these butterfly enthusiasts
0:52:31 > 0:52:33who are sitting there, waiting in their gardens
0:52:33 > 0:52:35for the arrival of the Painted Lady.
0:52:35 > 0:52:38The eastern route, having benefited from good weather
0:52:38 > 0:52:40throughout the year, is reaping rewards,
0:52:40 > 0:52:43and none more so than Crete.
0:52:43 > 0:52:45So, Crete has been an absolute hot spot.
0:52:45 > 0:52:46Let me prove it to you, actually,
0:52:46 > 0:52:48because one of our butterfly spotters
0:52:48 > 0:52:51has sent us in a video, and...
0:52:51 > 0:52:53This is from a guy called David Cook,
0:52:53 > 0:52:56who is on holiday in Crete at the moment,
0:52:56 > 0:52:58and he sent in this footage of Painted Ladies.
0:52:59 > 0:53:01Hi, I'm Dave Cook,
0:53:01 > 0:53:04I'm holidaying on the Greek island of Crete.
0:53:04 > 0:53:07It's a bit like a motorway service station for butterflies.
0:53:07 > 0:53:10I've never seen so many Painted Ladies in one place!
0:53:10 > 0:53:12Actually... So, he's counted them,
0:53:12 > 0:53:16and there's between 50 and 100 per bush.
0:53:16 > 0:53:19- That's amazing.- He's only ever seen one or two in the UK,
0:53:19 > 0:53:21so he's booked this holiday to Crete,
0:53:21 > 0:53:23hoping that the Painted Ladies were going to be there,
0:53:23 > 0:53:24and lo and behold they were.
0:53:24 > 0:53:27So, he's ditched his family, they're on the beach.
0:53:27 > 0:53:29They're on the beach just, you know, having a holiday.
0:53:29 > 0:53:32- He's out butterfly spotting for us. - Yeah.- It's brilliant.
0:53:32 > 0:53:35I'm feeling a butterfly divorce coming on, you know.
0:53:35 > 0:53:37- That's exactly what I would do on holiday.- Really?
0:53:37 > 0:53:40- Absolutely, ask my wife. - I'm not going on holiday with you!
0:53:40 > 0:53:42THEY LAUGH
0:53:43 > 0:53:45Coming out of such a horrendous June,
0:53:45 > 0:53:48it's no surprise our British spotters
0:53:48 > 0:53:51didn't have as much luck as Dave Cook in Crete.
0:53:52 > 0:53:57So how can scientists detect when Painted Ladies do arrive in the UK?
0:53:57 > 0:53:59James has the answer.
0:53:59 > 0:54:01Now, we know that thousands upon thousands
0:54:01 > 0:54:03of Painted Lady butterflies
0:54:03 > 0:54:06make this incredible journey every single year,
0:54:06 > 0:54:09but it's not as if we see them sort of flocking past our heads,
0:54:09 > 0:54:12and that's because they do it in a rather efficient way.
0:54:12 > 0:54:15I like to think of it as the insect highway in the sky,
0:54:15 > 0:54:18flying at these incredible heights, at these incredible wind speeds,
0:54:18 > 0:54:20and these things can survive this.
0:54:20 > 0:54:21It's actually amazing.
0:54:21 > 0:54:25And the way that scientists know this is by using this -
0:54:25 > 0:54:26the vertical-looking radar.
0:54:28 > 0:54:30It might appear little more than a satellite dish,
0:54:30 > 0:54:33but as the old saying goes, never judge a book by its cover.
0:54:33 > 0:54:37'Insect migration expert Dr Jason Chapman
0:54:37 > 0:54:40'is the custodian of this cutting-edge piece of kit.'
0:54:41 > 0:54:45So, this dish is basically reflecting a beam up into the sky?
0:54:45 > 0:54:47That's right, yeah. It's like shining a searchlight into the sky.
0:54:47 > 0:54:50Basically, we're hoping that insects will pass through that beam
0:54:50 > 0:54:52so we can detect them.
0:54:52 > 0:54:54It's kind of a cone shape as it's going up in the sky.
0:54:54 > 0:54:57Yeah. So, it's a very narrow cone. It just spreads out a little bit,
0:54:57 > 0:55:00but by the time it gets to our highest altitude,
0:55:00 > 0:55:01which is 1.2km,
0:55:01 > 0:55:03it's still only 30 metres wide,
0:55:03 > 0:55:04so it is quite a narrow sliver
0:55:04 > 0:55:06of the sky that we're sampling.
0:55:06 > 0:55:08On a sunny summer's day like today,
0:55:08 > 0:55:11we might expect maybe two, three, four...5,000 individuals.
0:55:11 > 0:55:13- Thousand?!- Yes.
0:55:13 > 0:55:15'Different insect species fly at different heights.
0:55:15 > 0:55:18'Painted Ladies pass through the beam at a much higher altitude
0:55:18 > 0:55:19'than most butterflies.
0:55:19 > 0:55:22'But it takes more than just the height they fly at
0:55:22 > 0:55:25'to confirm they're Painted Ladies.'
0:55:25 > 0:55:27The reason that we can identify and classify
0:55:27 > 0:55:28different kinds of insects
0:55:28 > 0:55:30is because they're different shapes and sizes
0:55:30 > 0:55:32and their different wing-beating frequencies
0:55:32 > 0:55:34produce very different signals.
0:55:34 > 0:55:37So, when you see a butterfly in the sky with the radar,
0:55:37 > 0:55:38how do you know it's on the migration?
0:55:38 > 0:55:41When you see hundreds of individuals flying over on the same day
0:55:41 > 0:55:44in the same direction, then you can see that there must be
0:55:44 > 0:55:47a population-level migration going on.
0:55:47 > 0:55:50For us to see what the vertical radar sees at altitude,
0:55:50 > 0:55:52we need to go inside.
0:55:52 > 0:55:56So, this is the computer that controls the operation of the radar.
0:55:56 > 0:55:59As insects passes through, we'll get a peak
0:55:59 > 0:56:01- as an individual flies through the beam.- Oh, yeah.
0:56:01 > 0:56:04Yeah, so you can see the peaks happening.
0:56:04 > 0:56:06They're quite quick, just within a couple of seconds.
0:56:08 > 0:56:11This graph represents a Painted Lady butterfly?
0:56:11 > 0:56:14That's right. It's a signal that we recorded from a Painted Lady
0:56:14 > 0:56:16flying over the radar.
0:56:16 > 0:56:19So, that peak tells you how big the insect is?
0:56:19 > 0:56:21Yes, so the magnitude of the peak,
0:56:21 > 0:56:24the amount of power that is being reflected,
0:56:24 > 0:56:25that will give you some indication
0:56:25 > 0:56:27about the overall size of the insect.
0:56:27 > 0:56:30OK, and along this bottom axis, we've got time,
0:56:30 > 0:56:31and it's three seconds here, or so.
0:56:31 > 0:56:34So, within a couple of seconds, that insect, of that size,
0:56:34 > 0:56:35passed through the beam.
0:56:35 > 0:56:38That's right. And so in two seconds, it passed through our beam,
0:56:38 > 0:56:40which is about 20 metres' diameter.
0:56:40 > 0:56:42- Yeah, yeah.- So a very quick calculation tells you
0:56:42 > 0:56:45that it was travelling at ten metres per second,
0:56:45 > 0:56:46that's about 40kmph.
0:56:46 > 0:56:48This one clearly was on the move.
0:56:48 > 0:56:50- Yeah.- Must have been part of the migration.
0:56:50 > 0:56:55Incredibly, they do so at heights of over 1,000 metres.
0:56:55 > 0:56:58Only one type of butterfly travels north in large numbers
0:56:58 > 0:57:00and at that height this time of year,
0:57:00 > 0:57:03so they can only be Painted Ladies.
0:57:03 > 0:57:05Maps from previous years provide confirmation.
0:57:07 > 0:57:08Each of those black bars
0:57:08 > 0:57:11is related to the numbers of individuals
0:57:11 > 0:57:13that were flying in that direction.
0:57:13 > 0:57:15And that's what we would expect during the early spring migration
0:57:15 > 0:57:18as these butterflies are travelling northwards.
0:57:18 > 0:57:21If the Painted Ladies were not migrating north,
0:57:21 > 0:57:23the map would look something like this.
0:57:23 > 0:57:27Multidirectional flight paths indicate an insect
0:57:27 > 0:57:29with no particular place to go.
0:57:32 > 0:57:36I've had an insight into what is normally a completely hidden part
0:57:36 > 0:57:39of the Painted Lady butterfly's migration and its world.
0:57:39 > 0:57:42It's allowed scientists to unravel and unlock
0:57:42 > 0:57:46some of the amazing secrets of this incredible migration
0:57:46 > 0:57:48that these tiny, fragile butterflies make.
0:57:49 > 0:57:52When our Painted Ladies do finally arrive,
0:57:52 > 0:57:54they're going to need refreshment.
0:57:54 > 0:57:57So, how can we prepare for their arrival?
0:58:05 > 0:58:09Long-distance athletes need regular refuelling,
0:58:09 > 0:58:11otherwise it affects their endurance.
0:58:11 > 0:58:15And, you know, it's exactly the same thing with Painted Ladies.
0:58:15 > 0:58:18When they come here after that monumental journey,
0:58:18 > 0:58:22they're hungry - they need nectar, sugar, for energy.
0:58:22 > 0:58:24And there are all sorts of things
0:58:24 > 0:58:27that we can do in our own gardens to help them.
0:58:27 > 0:58:29Patrick Barkham is going to show me how.
0:58:30 > 0:58:34Patrick is a natural history journalist and author.
0:58:34 > 0:58:38He's so obsessed with butterflies that in the space of one year,
0:58:38 > 0:58:42he tracked down every British species for a book.
0:58:42 > 0:58:46He's turned his Suffolk garden into a wildlife haven.
0:58:47 > 0:58:51Why is this so particularly good for butterflies?
0:58:51 > 0:58:54Well, it's very simple, really. I've planted some
0:58:54 > 0:58:55typical wildflower mixes.
0:58:55 > 0:58:58I tried to find mixes that use native species to Britain,
0:58:58 > 0:59:00not just exotic mixes.
0:59:00 > 0:59:04It looks like a sort of fairly scruffy lawn, to some eyes,
0:59:04 > 0:59:06but there's loads of grass-feeding butterflies
0:59:06 > 0:59:08that actually lay their eggs,
0:59:08 > 0:59:09the caterpillars feed on the grasses.
0:59:09 > 0:59:12Then, of course, you chuck in a load of wildflower mix
0:59:12 > 0:59:15and you get these lovely wildflowers on which the butterflies can nectar.
0:59:15 > 0:59:17And you've got some fantastic daisies here.
0:59:17 > 0:59:20These are great, and these surprised me,
0:59:20 > 0:59:24because I saw 19 Painted Ladies on these a couple of weeks ago,
0:59:24 > 0:59:25just round the corner.
0:59:25 > 0:59:27So the Painted Ladies come in on this enormous journey
0:59:27 > 0:59:29and it's seen my ox-eye daisies
0:59:29 > 0:59:32and it's dropping down to refuel, you know, it's a lovely thing.
0:59:32 > 0:59:34And then I went to look for them the next day
0:59:34 > 0:59:36and they'd all disappeared again,
0:59:36 > 0:59:38so they'd all continued their journey north.
0:59:38 > 0:59:42All that effort - you've planted these fantastic wildflowers,
0:59:42 > 0:59:44and then they just disappear!
0:59:44 > 0:59:46They race through your garden in 30 seconds
0:59:46 > 0:59:49and have a quick fuel stop and then zoom off again.
0:59:49 > 0:59:52To me, that's great and that's enough,
0:59:52 > 0:59:55but the next thing is you want them breeding in your garden.
0:59:55 > 0:59:58You really want their food plant, thistle,
0:59:58 > 1:00:00and thistle is not such an easy sell, is it?
1:00:00 > 1:00:04- No.- I've got these enormous thistles by my front door.
1:00:04 > 1:00:06It's quite hard, isn't it,
1:00:06 > 1:00:08to ask keen gardeners to let thistles grow?
1:00:08 > 1:00:10It's a real struggle - even I struggle with thistles.
1:00:10 > 1:00:14This is a lovely example of how if you do something for butterflies,
1:00:14 > 1:00:18it helps all kinds of wildlife, cos I found another caterpillar,
1:00:18 > 1:00:20and it's somewhere on this plant here,
1:00:20 > 1:00:22and it's the caterpillar of an Angle Shades moth.
1:00:22 > 1:00:25I took a little picture of it
1:00:25 > 1:00:27and, helpfully, someone identified it for me.
1:00:27 > 1:00:29And it's this wonderful insect,
1:00:29 > 1:00:31and the caterpillar comes out at night
1:00:31 > 1:00:33and munches away at the thistle
1:00:33 > 1:00:36and soon it will pupate and become this beautiful, beautiful moth.
1:00:38 > 1:00:41Patrick's garden is full of low-maintenance plants
1:00:41 > 1:00:44that we can all easily grow in our own gardens.
1:00:44 > 1:00:46So, got some buddleias here,
1:00:46 > 1:00:49and some slightly smelly garden gloves.
1:00:49 > 1:00:53Oh, don't worry, they can't be any worse than mine, I can promise you.
1:00:53 > 1:00:55And there is a trowel and some spades
1:00:55 > 1:00:57and here's our buddleias.
1:00:58 > 1:01:00'I'm not averse to a bit of gardening,
1:01:00 > 1:01:05'and I'm keen to lend Patrick a hand replenishing his butterfly oasis.'
1:01:05 > 1:01:07So, where do you want me to start?
1:01:07 > 1:01:10So, I'd just stick one at the back of the lavender -
1:01:10 > 1:01:12more or less where that spade is would be fine.
1:01:12 > 1:01:15- OK, great.- You can dig out these. These are just little weeds.
1:01:15 > 1:01:17Don't get stung by the nettles
1:01:17 > 1:01:19that I've left there for the small Tortoiseshells.
1:01:19 > 1:01:21Do you know, my garden is...
1:01:21 > 1:01:24I've left a lot of nettles for butterflies
1:01:24 > 1:01:27- but, blimey, they do spread, don't they?- Yeah, they do.
1:01:27 > 1:01:30I really love the idea that you can look out in your garden,
1:01:30 > 1:01:33you can see that you've got nettles and thistles
1:01:33 > 1:01:34and things like that, and you can think,
1:01:34 > 1:01:36"I'm not a lazy gardener,
1:01:36 > 1:01:38"I'm doing something that's incredibly moral,
1:01:38 > 1:01:40- "I'm saving butterflies." - Yeah, exactly.
1:01:40 > 1:01:43- So, are you happy for this to go in here?- Yeah, yeah.
1:01:43 > 1:01:47Buddleia is by far the most popular nectar plant of British butterflies.
1:01:47 > 1:01:51A favourite of 18 species, including the Painted Lady,
1:01:51 > 1:01:53it's not called the butterfly bush for nothing.
1:01:53 > 1:01:55I just took these from cuttings,
1:01:55 > 1:01:58and I just literally take a cutting of buddleia,
1:01:58 > 1:02:00stick it in a pot like this, leave it for a few months
1:02:00 > 1:02:02and then you get a buddleia
1:02:02 > 1:02:05and you don't have to spend £10 at a garden centre for one.
1:02:05 > 1:02:08It's really important to think about plants that will keep going
1:02:08 > 1:02:10right through the year,
1:02:10 > 1:02:13particularly when there aren't so many other flowers around.
1:02:13 > 1:02:15That's right. The nectar sources at the end of the summer,
1:02:15 > 1:02:18when everything else has died back, they are the real key.
1:02:20 > 1:02:24Butterflies in the garden are a marker of a healthy ecosystem.
1:02:24 > 1:02:27Get things right for them, you get things right for other wildlife.
1:02:27 > 1:02:32The value of caterpillars as a high-protein food source
1:02:32 > 1:02:35for breeding birds, for example, is invaluable.
1:02:35 > 1:02:38Butterflies are also effective pollinators.
1:02:38 > 1:02:42When feeding, pollen sticks to hairs that cover their body
1:02:42 > 1:02:44and is passed from flower to flower.
1:02:44 > 1:02:46But they're in decline.
1:02:46 > 1:02:50Industrial agriculture, habitat loss and changes to the weather
1:02:50 > 1:02:55have seen the numbers drop by 70% in recent years.
1:02:55 > 1:02:58Anything we can do for butterflies in our gardens
1:02:58 > 1:02:59might help buck the trend.
1:02:59 > 1:03:04The butterfly flower I wanted to show you, Martha, is this.
1:03:04 > 1:03:06- Ivy?- Yeah.- OK.
1:03:06 > 1:03:09One of the best things you can have for butterflies in your garden.
1:03:09 > 1:03:11It flowers really late in the season, doesn't it?
1:03:11 > 1:03:14Yeah, and that's perfect for the butterflies like the Red Admiral
1:03:14 > 1:03:18that need energy late in the summer to hibernate through the winter.
1:03:18 > 1:03:19The other thing that's brilliant,
1:03:19 > 1:03:21this is another great thing for the lazy gardener, isn't it?
1:03:21 > 1:03:23- I guess it is. - THEY LAUGH
1:03:23 > 1:03:28All around Patrick's garden is a one-stop butterfly buffet.
1:03:28 > 1:03:32So, this is garlic mustard, or jack-by-the-hedge.
1:03:32 > 1:03:35This is a weed you'll see under almost any hedgerow,
1:03:35 > 1:03:37and it is the food plant for the Orange Tip.
1:03:37 > 1:03:40If it has butterflies on it,
1:03:40 > 1:03:42then it becomes a really beautiful thing.
1:03:42 > 1:03:45Yeah, and it becomes a precious thing, and you start thinking,
1:03:45 > 1:03:47"Well, I'd better not cut that back
1:03:47 > 1:03:49"because there might be a butterfly egg on it,"
1:03:49 > 1:03:51and it does start making you think.
1:04:00 > 1:04:03With the UK now basking in summer sunshine,
1:04:03 > 1:04:06conditions are perfect for Painted Ladies.
1:04:06 > 1:04:11And after such a long wait, they've finally made it here.
1:04:20 > 1:04:21They will be hungry,
1:04:21 > 1:04:24and with flowers up and down the country in full bloom,
1:04:24 > 1:04:27Painted Ladies made it just in time.
1:04:31 > 1:04:34It took a while, but in late June, early July,
1:04:34 > 1:04:40the class of 2016 eventually hit our shores in significant numbers.
1:04:48 > 1:04:52Around the country, our spotters are on a winning streak.
1:04:52 > 1:04:55Marie and David Law found their Painted Lady
1:04:55 > 1:04:58on the busy streets of Skegness.
1:04:58 > 1:04:59Turn the right way round!
1:05:04 > 1:05:07- We have two today.- Two? - Two Painted Ladies.
1:05:09 > 1:05:11Tell me facts about Painted Lady butterflies.
1:05:11 > 1:05:13They fly from Morocco.
1:05:13 > 1:05:14Well done.
1:05:14 > 1:05:17- Yeah? Go on.- To here, some of them.
1:05:17 > 1:05:19OK, they fly from Morocco.
1:05:19 > 1:05:22- Yeah.- Through Spain.
1:05:22 > 1:05:24- Yeah.- Through France.
1:05:24 > 1:05:26- Sometimes, yeah.- Then here.
1:05:26 > 1:05:30- Yeah.- Or they can fly straight from Morocco to here.- Yeah.
1:05:30 > 1:05:34Come to me, butterfly, land on my hand.
1:05:34 > 1:05:36- Oh, wouldn't that be nice? - It would!
1:05:36 > 1:05:38Marie and David have a knack
1:05:38 > 1:05:41for being in the right place at the right time for Painted Ladies.
1:05:41 > 1:05:44Oh, look, it's one of the...
1:05:44 > 1:05:46- Oh, no, there's one there. - Yeah, there is.
1:05:47 > 1:05:51Very top. Right here.
1:05:51 > 1:05:53Oh, another one.
1:05:53 > 1:05:57- Painted Lady butterfly, definitely. - It's definitely a Painted Lady. - Definitely.
1:05:57 > 1:05:59- It's not a Cabbage White.- No.
1:05:59 > 1:06:00Go on, run up and see.
1:06:00 > 1:06:02Is it a brown one? Is it...?
1:06:02 > 1:06:06- No, it's not, it's a Speckled Wood. - Speckled Wood, yeah?
1:06:06 > 1:06:08That was a Speckled Wood.
1:06:08 > 1:06:10Last year, they witnessed something
1:06:10 > 1:06:13even the most experienced butterfly scientists
1:06:13 > 1:06:15would be lucky to see.
1:06:15 > 1:06:17- We're at Skegness Gibraltar Pond nature reserve.- Yeah.
1:06:17 > 1:06:19- We're here...- We...
1:06:19 > 1:06:20THEY LAUGH
1:06:20 > 1:06:23We are here because in June,
1:06:23 > 1:06:28we saw two Painted Lady butterflies that were just about to mate.
1:06:28 > 1:06:32It was one of those moments where you just happened to walk about
1:06:32 > 1:06:35and you just notice that one little thing that is different,
1:06:35 > 1:06:37just that one...
1:06:37 > 1:06:38They were acting a bit unusual,
1:06:38 > 1:06:40that's not normally what butterflies do,
1:06:40 > 1:06:43and then you take a close look and, "Oh, there are two of them."
1:06:43 > 1:06:45There's two of them here. They could be just about to mate.
1:06:45 > 1:06:47They were very close.
1:06:48 > 1:06:51He was... He was getting closer and closer and closer to it
1:06:51 > 1:06:53and then they just flew off.
1:06:56 > 1:06:59They landed together, I got some shots, both flew off,
1:06:59 > 1:07:00came back to exactly the same spot.
1:07:00 > 1:07:03- They did.- Which means that was probably the male's territory.
1:07:03 > 1:07:05- Just right there.- It was down here.
1:07:05 > 1:07:07Back at Rothamsted,
1:07:07 > 1:07:10butterfly migration specialist Rebecca Nesbit
1:07:10 > 1:07:13has worked with an incredible piece of kit
1:07:13 > 1:07:17that could help us understand what Painted Ladies get up to
1:07:17 > 1:07:18now that they're here.
1:07:18 > 1:07:23To do this, she tracks Painted Lady flight patterns using radar
1:07:23 > 1:07:26and is going to show James how to do it.
1:07:27 > 1:07:28- Hi, Rebecca.- Hello.
1:07:28 > 1:07:32So, tell me, how on earth do you put a radio antenna
1:07:32 > 1:07:35onto the back of a butterfly?
1:07:35 > 1:07:38So, first we have to trap it down.
1:07:40 > 1:07:42As with the flight simulator experiment,
1:07:42 > 1:07:46you have to shave a Painted Lady before attaching anything to it.
1:07:46 > 1:07:49Rebecca showed me earlier, so now it is my turn.
1:07:49 > 1:07:51- Here is your butterfly.- Yeah.
1:07:51 > 1:07:53Oh, no, no! Is that OK?
1:07:53 > 1:07:55- Oh, no.- Come back!
1:07:55 > 1:07:57- Yeah, give it a go.- Got it.
1:07:57 > 1:07:58It's quite a lively butterfly.
1:07:58 > 1:08:01Oh, now, you can do this. Behave.
1:08:01 > 1:08:03There we go. Oh, no.
1:08:03 > 1:08:05This is embarrassing. I've made such a mess of it.
1:08:07 > 1:08:09Yes! Yes, I've done it.
1:08:09 > 1:08:11I handle insects all the time,
1:08:11 > 1:08:13but I don't know why my hands are completely shaking,
1:08:13 > 1:08:15and I think because you did it so professionally,
1:08:15 > 1:08:17I'm so nervous about doing it badly.
1:08:17 > 1:08:21If you think about it too much, your hands definitely start shaking.
1:08:21 > 1:08:22OK, brilliant.
1:08:22 > 1:08:26'A gentle rub and my first butterfly haircut is done.'
1:08:28 > 1:08:32Once glued on, this tiny radio antenna weighs almost nothing.
1:08:32 > 1:08:35What it lacks in size, it makes up for with what it can do.
1:08:37 > 1:08:41This technology is the creation of Dr Jason Lim,
1:08:41 > 1:08:44one of the world's leading experts in insect tracking devices.
1:08:44 > 1:08:46Called a harmonic radar,
1:08:46 > 1:08:50it is able to pick up the antenna attached to the Painted Lady's back
1:08:50 > 1:08:52using a specific wavelength.
1:08:53 > 1:08:56It's then able to track the Painted Lady as it flies.
1:08:57 > 1:08:59So, does it come off eventually or...?
1:08:59 > 1:09:01It will just fall off after a few days.
1:09:05 > 1:09:07This may look heavy,
1:09:07 > 1:09:09but it's extremely lightweight and harmless,
1:09:09 > 1:09:12and doesn't affect the Painted Lady's ability to fly.
1:09:16 > 1:09:18Butterflies require energy to fly,
1:09:18 > 1:09:21so topping my one up beforehand is a good idea.
1:09:23 > 1:09:26Unravelling the proboscis takes not only skill
1:09:26 > 1:09:28but a willing participant.
1:09:31 > 1:09:33The proboscis is a long, narrow tube,
1:09:33 > 1:09:37a feeding straw designed to get deep into nectar-rich flowers.
1:09:39 > 1:09:42In this instance, sugar water on a cloth will do.
1:09:44 > 1:09:45It takes a while,
1:09:45 > 1:09:48but we do eventually get the butterfly to eat something.
1:09:50 > 1:09:52Having had its pre-flight meal,
1:09:52 > 1:09:54my butterfly is now ready for takeoff.
1:10:06 > 1:10:09- And we are heading out to that release box.- Yeah.
1:10:09 > 1:10:13- And then, if it's OK, if you could just whip the string off...- OK.
1:10:13 > 1:10:15..and that lets the butterfly go free.
1:10:15 > 1:10:18- Conditions are good. - Absolutely perfect,
1:10:18 > 1:10:20particularly when the sun comes out.
1:10:20 > 1:10:21Well, this one seems OK.
1:10:21 > 1:10:23Perfectly happy, looks quite calm.
1:10:23 > 1:10:25We put the pot right down on the floor...
1:10:25 > 1:10:28- Yeah.- Tip the butterfly out and then I will close it.
1:10:28 > 1:10:30Gosh, she's really active now, isn't she?
1:10:30 > 1:10:34Yes, that heat has instantly brought her out.
1:10:34 > 1:10:38As the sun comes out, so do our Painted Lady's wings.
1:10:38 > 1:10:40Acting like solar panels,
1:10:40 > 1:10:43they absorb sunlight to warm up flight muscles,
1:10:43 > 1:10:44ready for action.
1:10:45 > 1:10:47With my butterfly poised
1:10:47 > 1:10:51and Jason Lim's tracking radar spinning into action, we're ready.
1:10:51 > 1:10:54DRAMATIC MUSIC PLAYS
1:10:54 > 1:10:58OK, you can release the butterfly now, over.
1:10:58 > 1:11:01- Excellent. OK, he's ready. - He's ready? Great.- He's ready.
1:11:01 > 1:11:05- OK, stand back.- Stand back. - Just so we don't shade it.
1:11:05 > 1:11:07OK. And the sun is out. How perfect is this?
1:11:07 > 1:11:10- Quick.- And I just pull?- Yeah.- Pull.
1:11:10 > 1:11:12MUSIC STOPS SUDDENLY
1:11:12 > 1:11:15'I obviously peaked too early.
1:11:15 > 1:11:18'Taking this chance to sunbathe while it can,
1:11:18 > 1:11:21'my Painted Lady needs a little encouragement.'
1:11:21 > 1:11:23Fly, come on!
1:11:23 > 1:11:26The sun is out. Oh, it's going away again!
1:11:26 > 1:11:28Fly, come on!
1:11:30 > 1:11:32And then she's off.
1:11:32 > 1:11:34Jason, the butterfly is on the move.
1:11:34 > 1:11:37- OVER RADIO:- 'OK, over.
1:11:37 > 1:11:39'Butterfly is moving quite fast.
1:11:39 > 1:11:45'It's now flying towards the manor garden, over.'
1:11:46 > 1:11:49My Painted Lady stops for a refuel.
1:11:49 > 1:11:54Back in the van, Jason tracks it as it moves around Rothamsted.
1:11:54 > 1:11:57The radar can keep tabs on it from up to a kilometre away.
1:11:57 > 1:11:59So, where's our butterfly?
1:11:59 > 1:12:02That is the butterfly flying from here,
1:12:02 > 1:12:03so it is moving slowly.
1:12:03 > 1:12:05Yes, that's the one.
1:12:05 > 1:12:07This is a 100-metre ring.
1:12:07 > 1:12:11So we know the butterfly is 100 metres away from us.
1:12:11 > 1:12:13- Away from us. Yeah?- Yes.
1:12:13 > 1:12:15So, here is our release point.
1:12:15 > 1:12:17- OK.- So we can see the butterfly has flown
1:12:17 > 1:12:19about 50 metres away from there.
1:12:19 > 1:12:21- So it's on the move, then, clearly?- Yeah.
1:12:21 > 1:12:23That's brilliant that we're able to see this.
1:12:23 > 1:12:26- It's stopped now, though. - Yeah, so we just have to wait.
1:12:26 > 1:12:30Maybe it's just foraging below the radar, under the radar,
1:12:30 > 1:12:32where the radar couldn't pick up a signal from it.
1:12:32 > 1:12:36- OK.- So the machine allows us to track the position
1:12:36 > 1:12:38of the butterflies every three seconds.
1:12:38 > 1:12:41So the butterfly could do what they normally do -
1:12:41 > 1:12:44sunbathing to warm up the body
1:12:44 > 1:12:48and then they forage, flying around different patches of flowers
1:12:48 > 1:12:52and potentially looking for a mate as well.
1:12:52 > 1:12:54What a great piece of technology this is,
1:12:54 > 1:12:57allowing us to see into the life of the Painted Lady butterfly.
1:12:57 > 1:13:00And who knows what the future might hold for this?
1:13:00 > 1:13:03It might even allow us to unlock even more secrets
1:13:03 > 1:13:06of the Painted Lady butterfly migration.
1:13:06 > 1:13:09Tracking technology will no doubt advance
1:13:09 > 1:13:12and so too the distances that can be covered.
1:13:12 > 1:13:15You never know - one day, we might be able to track
1:13:15 > 1:13:18a Painted Lady all the way from Morocco to here.
1:13:26 > 1:13:30Our butterfly spotters don't need tracking devices.
1:13:30 > 1:13:33Now that it's July, Painted Ladies are coming to them.
1:13:33 > 1:13:37Dave Cook is back from Crete and out doing what he loves best.
1:13:39 > 1:13:41I've come here to the location, Brixton Common,
1:13:41 > 1:13:44with the specific intention of finding the Painted Lady
1:13:44 > 1:13:46that I found here this morning.
1:13:48 > 1:13:52She's still here and she's still nectaring.
1:13:53 > 1:13:55It's great. It's absolutely brilliant.
1:13:59 > 1:14:00Result.
1:14:02 > 1:14:04What it's all about.
1:14:06 > 1:14:10And Darcia from Wiltshire is equally pleased to be out and about
1:14:10 > 1:14:13spotting her favourite butterfly.
1:14:13 > 1:14:16I am Darcia Gingell and this is Morgan's Hill nature reserve,
1:14:16 > 1:14:18which is a Wiltshire Wildlife Trust site
1:14:18 > 1:14:20in North Wiltshire.
1:14:20 > 1:14:22And it's a gorgeous morning this morning,
1:14:22 > 1:14:25and we're here to hopefully try and find some Painted Ladies.
1:14:27 > 1:14:30It's actually quite difficult to get hold of a picture of a Painted Lady
1:14:30 > 1:14:33unless they're actually still and nectaring,
1:14:33 > 1:14:35because a lot of the time, they're quite fast flyers,
1:14:35 > 1:14:38so they'll zoom into view, maybe come around you,
1:14:38 > 1:14:42circle round you, take a look at you and then they're off.
1:14:42 > 1:14:44Unless you find them, as I've said, nectaring.
1:14:44 > 1:14:47Once they're in one place, maybe on a nice thistle,
1:14:47 > 1:14:49they tend to stay there, and you might even, you know,
1:14:49 > 1:14:53get a chance to take a glimpse of one for a few seconds,
1:14:53 > 1:14:54and they're off again.
1:14:54 > 1:14:57Quite a big butterfly there.
1:14:57 > 1:15:00No, small Tortoiseshell. Got my hopes up.
1:15:00 > 1:15:02About a week ago, me and my partner
1:15:02 > 1:15:04were at a place called Ravensroost Wood.
1:15:04 > 1:15:07Just walking along the track, next minute, "Whizz!"
1:15:07 > 1:15:09Round your head.
1:15:09 > 1:15:12Really shocked and surprised to actually see it was a Painted Lady.
1:15:12 > 1:15:15Just came and landed and settled on the floor in front of us.
1:15:15 > 1:15:17It's a beautiful butterfly.
1:15:18 > 1:15:21So, there we go.
1:15:21 > 1:15:25It's just flown along behind us and come and landed and settled.
1:15:25 > 1:15:26It's quite fascinating
1:15:26 > 1:15:29to think where this beautiful butterfly has come from.
1:15:31 > 1:15:33I think it's almost, like, magical when you actually see one,
1:15:33 > 1:15:36and I think it reminds you of those fairy tales
1:15:36 > 1:15:37when you were a child
1:15:37 > 1:15:40and you're imagining what a fairy really would be like,
1:15:40 > 1:15:43and I think a butterfly is the closest you can get to that.
1:15:55 > 1:15:59With Painted Ladies now being seen all over the country,
1:15:59 > 1:16:01how do we know just how successful
1:16:01 > 1:16:03the migration has been this year overall?
1:16:03 > 1:16:07'Richard Fox is part of Butterfly Conservation,
1:16:07 > 1:16:10'a definitive authority on British butterflies.
1:16:10 > 1:16:13'His migratory maps tell a fascinating story.'
1:16:13 > 1:16:16Your volunteers have been looking out for the Painted Lady,
1:16:16 > 1:16:18which, of course, we're following.
1:16:18 > 1:16:20Yes, so we've got some maps here
1:16:20 > 1:16:24of sightings of Painted Ladies from this year.
1:16:24 > 1:16:27So, each Painted Lady picture represents a place
1:16:27 > 1:16:30where members of the public have reported seeing Painted Ladies.
1:16:30 > 1:16:32And this is from... January and February?
1:16:32 > 1:16:34I'm amazed there are any Painted Ladies at all!
1:16:34 > 1:16:38Exactly. So, you often really wouldn't see any Painted Ladies
1:16:38 > 1:16:42in Britain at all over that January, February period in a normal year.
1:16:42 > 1:16:44But this year wasn't normal.
1:16:44 > 1:16:47We had a very, very mild spell over New Year
1:16:47 > 1:16:49and winds from the south,
1:16:49 > 1:16:51bringing Painted Ladies from North Africa,
1:16:51 > 1:16:53where they normally are at that time of year.
1:16:53 > 1:16:55These pioneering Painted Ladies
1:16:55 > 1:16:57coming up into southwest England, South Wales...
1:16:57 > 1:17:00But not just the south, I mean, there's Isle of Man,
1:17:00 > 1:17:01Northern Ireland.
1:17:01 > 1:17:03Some in Cumbria as well.
1:17:03 > 1:17:06So really amazing influx at that time of year.
1:17:06 > 1:17:10Painted Ladies normally start arriving here in May.
1:17:10 > 1:17:13But a very warm January meant one bucked the trend.
1:17:16 > 1:17:19They react very quickly to conditions around them.
1:17:19 > 1:17:22Tropical air blowing in from Africa
1:17:22 > 1:17:25saw Britain bask in unseasonably warm weather
1:17:25 > 1:17:27at the beginning of the year.
1:17:27 > 1:17:30With the warm winds came the first Painted Lady sighting,
1:17:30 > 1:17:33in Somerset in south-west England,
1:17:33 > 1:17:36as early as January 3rd this year.
1:17:37 > 1:17:41It had flown the 2,500km from where I was in Morocco
1:17:41 > 1:17:43to here in a matter of days.
1:17:45 > 1:17:47But that's not the earliest on record.
1:17:47 > 1:17:52Remarkably, one was spotted on New Year's Day in 2013.
1:17:53 > 1:17:56Painted Ladies that fly here early in a single journey
1:17:56 > 1:17:58are known as pioneers.
1:17:59 > 1:18:02Unfortunately, these pioneers will perish
1:18:02 > 1:18:04once the weather turns cold again.
1:18:06 > 1:18:11And then we come on to the spring, a few more.
1:18:11 > 1:18:12Yes, there were a few more,
1:18:12 > 1:18:15but the weather really wasn't very good this spring.
1:18:15 > 1:18:17It was colder than usual,
1:18:17 > 1:18:19it was very wet in some places.
1:18:19 > 1:18:21So although we're seeing more butterflies,
1:18:21 > 1:18:24as you'd expect, there's nothing very much going on.
1:18:24 > 1:18:26So, we move on to the next one - the summer.
1:18:28 > 1:18:31And what a summer, albeit delayed.
1:18:31 > 1:18:33In late June through July,
1:18:33 > 1:18:37sightings erupted across the country.
1:18:37 > 1:18:39So, these are Painted Ladies
1:18:39 > 1:18:40not coming direct from North Africa,
1:18:40 > 1:18:44but coming up from Spain, Portugal, southern France.
1:18:44 > 1:18:46It's an explosion of Painted Ladies.
1:18:46 > 1:18:49There's barely a part of the country that doesn't have Painted Ladies.
1:18:49 > 1:18:50That's right, and indeed,
1:18:50 > 1:18:52even the places where they haven't been recorded,
1:18:52 > 1:18:56they may well have been there, just not been spotted by people.
1:18:56 > 1:18:58These Painted Ladies aren't coming from North Africa,
1:18:58 > 1:19:00as the ones in January and February were -
1:19:00 > 1:19:03these are moving up from southern parts of Europe,
1:19:03 > 1:19:04so they're kind of a generation on.
1:19:04 > 1:19:07But, really, all over the country, as you can see.
1:19:07 > 1:19:10Yeah, the far north of Scotland - out in the Hebrides.
1:19:10 > 1:19:12Really good concentrations
1:19:12 > 1:19:13down in the southwest.
1:19:13 > 1:19:16We had people on the Isles of Scilly and in west Cornwall
1:19:16 > 1:19:20who saw, you know, 50 or even 100 Painted Ladies in a single day,
1:19:20 > 1:19:23so there were some quite good numbers around at this time.
1:19:23 > 1:19:26So we hear so much about the kind of problems,
1:19:26 > 1:19:28the troubles that butterflies are in.
1:19:28 > 1:19:30What about Painted Ladies?
1:19:30 > 1:19:33Well, Painted Ladies are a very adaptable species.
1:19:33 > 1:19:35They are obviously highly mobile, they are nomadic,
1:19:35 > 1:19:37they don't live in particular places,
1:19:37 > 1:19:39and most importantly, I guess,
1:19:39 > 1:19:41the food that their caterpillars need
1:19:41 > 1:19:43is mainly thistles, in this country,
1:19:43 > 1:19:45that's mainly what the caterpillars are eating
1:19:45 > 1:19:48and, of course, they're very common and widespread.
1:19:48 > 1:19:50So, actually, Painted Ladies have done really well
1:19:50 > 1:19:51in Britain over the past 40 years.
1:19:51 > 1:19:53Oh, that's really good to hear.
1:20:04 > 1:20:09To get here, Painted Ladies started out from Morocco in late March.
1:20:09 > 1:20:12Following the appearance of the foods they feed on,
1:20:12 > 1:20:15they arrived in Spain in April to breed,
1:20:15 > 1:20:19a new generation carrying out the next stage of the journey
1:20:19 > 1:20:21through France in May.
1:20:21 > 1:20:23Few made it to Britain in May,
1:20:23 > 1:20:26bad weather delaying their arrival in significant numbers
1:20:26 > 1:20:28until late June, early July.
1:20:28 > 1:20:30The Painted Ladies we see now
1:20:30 > 1:20:34are the grandchildren of ones that left Morocco.
1:20:34 > 1:20:36Generations born in this country
1:20:36 > 1:20:39will then continue to push further north towards the Arctic
1:20:39 > 1:20:41before the summer is out.
1:20:48 > 1:20:51Basking in the British sunshine in July,
1:20:51 > 1:20:53Painted Ladies are a welcome sight.
1:20:53 > 1:20:56This is what our spotters have been waiting for.
1:20:58 > 1:21:01Like Dave and Agnes in Dorset, who found a beauty.
1:21:12 > 1:21:14It's very colourful. Yes!
1:21:15 > 1:21:19You can see how fresh she is, she's got that metallic glow on her.
1:21:19 > 1:21:22Yeah, she's only been out a day. If not this morning.
1:21:22 > 1:21:24Fantastic.
1:21:26 > 1:21:27THEY CHUCKLE
1:21:31 > 1:21:33The numbers are definitely starting to build.
1:21:35 > 1:21:38- She is warming up really nicely, isn't she?- Yeah.- Brilliant.
1:21:40 > 1:21:42Dave and Agnes are just the tip of the iceberg.
1:21:42 > 1:21:47Spotters from all over the country are seeing our Ladies regularly now,
1:21:47 > 1:21:49and the pictures are rolling in.
1:21:49 > 1:21:52People have been sending all sorts of pictures - not all butterflies!
1:21:52 > 1:21:53But this is a really good one.
1:21:53 > 1:21:56And do you know what? This is a guy called Adam Middleton,
1:21:56 > 1:21:57and guess what.
1:21:57 > 1:21:59- He's only 14 years old.- That's...
1:21:59 > 1:22:02- The image is so sharp.- Isn't it? - You can really see the antennae.
1:22:02 > 1:22:04It is absolutely brilliant.
1:22:04 > 1:22:06You can see the eye here, the antennae,
1:22:06 > 1:22:07and it's got its proboscis out,
1:22:07 > 1:22:09it was obviously trying to feed on nectar there.
1:22:09 > 1:22:12It's really hard to get a picture like this
1:22:12 > 1:22:14of a butterfly in the wild.
1:22:14 > 1:22:15And he's 14 years old,
1:22:15 > 1:22:17so not only is he a fantastic butterfly spotter,
1:22:17 > 1:22:20he's a pretty good photographer as well.
1:22:20 > 1:22:22Here's a young man who will be after your job one of these days.
1:22:22 > 1:22:24- LAUGHING:- Yeah, probably.
1:22:24 > 1:22:26It's so important that people do this.
1:22:26 > 1:22:30You know, scientists are relying on data from people that are, you know,
1:22:30 > 1:22:33doing all of this, taking pictures, sightings,
1:22:33 > 1:22:36so that they can record them and see what is happening with the migration
1:22:36 > 1:22:38from a conservation point of view.
1:22:38 > 1:22:40What I like is the way that people have been doing it
1:22:40 > 1:22:43in our country for hundreds of years,
1:22:43 > 1:22:44so we have the best biological data, don't we?
1:22:44 > 1:22:47- That's right. - We've been doing it for so long.
1:22:47 > 1:22:49We're a nation of butterfly spotters.
1:22:52 > 1:22:55All the Painted Ladies our spotters are seeing
1:22:55 > 1:22:57are this year's Moroccan descendants.
1:22:57 > 1:23:00When I joined the world's leading Painted Lady expert,
1:23:00 > 1:23:03Constanti Stefanescu, earlier in the year,
1:23:03 > 1:23:05he was piecing together the puzzle
1:23:05 > 1:23:09of why Painted Ladies migrate in the first place.
1:23:09 > 1:23:13It's taken him ten years of extensive research
1:23:13 > 1:23:16to establish the facts and reach a definitive conclusion.
1:23:17 > 1:23:20After countless expeditions to Morocco
1:23:20 > 1:23:24and painstaking data analysis in Spain,
1:23:24 > 1:23:25what has he found out?
1:23:29 > 1:23:33Well, the butterflies are going absolutely crazy in here,
1:23:33 > 1:23:37and it's rather perfect for us to be able to welcome Doctor Constanti.
1:23:37 > 1:23:39It seems a long time ago
1:23:39 > 1:23:42since we were filming together in Morocco, doesn't it?
1:23:42 > 1:23:45Yeah, yeah, it's far away.
1:23:45 > 1:23:49But they clearly found you as a butterfly fan.
1:23:49 > 1:23:51Now, tell me about your discovery
1:23:51 > 1:23:53and all the work that you've been doing,
1:23:53 > 1:23:55which I was happy to be a part of.
1:23:55 > 1:24:02Well, I started to collect caterpillars of the Painted Lady,
1:24:02 > 1:24:06to see which were its natural enemies, many years ago,
1:24:06 > 1:24:08maybe ten years ago.
1:24:08 > 1:24:14Immediately I realised that these wasps can be very, very important.
1:24:14 > 1:24:18And then I thought that maybe migration could be...
1:24:20 > 1:24:24..a way to escape this mortality, to these little wasps.
1:24:26 > 1:24:29Constanti's research indicates that Painted Ladies leave Morocco
1:24:29 > 1:24:33at a specific time of year to escape from their deadly enemy,
1:24:33 > 1:24:35the Cotesia wasp.
1:24:35 > 1:24:38If they don't, they die.
1:24:38 > 1:24:40When I collected the caterpillars in Morocco,
1:24:40 > 1:24:47I was afraid that maybe the results would not support the idea.
1:24:47 > 1:24:51But when I brought back these caterpillars to Catalonia,
1:24:51 > 1:24:56immediately they started to die because of this parasite.
1:24:56 > 1:24:59So, yeah, I am very happy about that.
1:24:59 > 1:25:03So, how would you sum up your discovery this year?
1:25:03 > 1:25:08Well, I would say that the data that we gathered this year
1:25:08 > 1:25:12is the first clear demonstration
1:25:12 > 1:25:17that natural enemies is also one of the factors
1:25:17 > 1:25:20that are important for migration.
1:25:20 > 1:25:24Still analysing some data, but the results are very clear,
1:25:24 > 1:25:29so I am absolutely confident about what we have found.
1:25:31 > 1:25:34Constanti has cracked it.
1:25:34 > 1:25:37'His ten-year investigation has revealed astonishing new facts
1:25:37 > 1:25:40'about the Painted Lady migration.'
1:25:40 > 1:25:41Yes.
1:25:41 > 1:25:44'Tiny wasps are the Painted Lady's nemesis in Morocco,
1:25:44 > 1:25:47'laying eggs inside caterpillars
1:25:47 > 1:25:50'and subsequently killing them on a grand scale.'
1:25:51 > 1:25:53As Painted Ladies breed,
1:25:53 > 1:25:56so too do the wasps, in huge numbers.
1:25:56 > 1:25:59At some point during the breeding season,
1:25:59 > 1:26:02Painted Ladies have to leave Morocco to survive.
1:26:03 > 1:26:08This is ground-breaking news, a scientific first for Constanti.
1:26:08 > 1:26:11His dedicated research has paid off
1:26:11 > 1:26:15and added another reason why Painted Ladies migrate
1:26:15 > 1:26:17in the first place.
1:26:17 > 1:26:20Not only do they move to follow their food source,
1:26:20 > 1:26:21as previously known...
1:26:23 > 1:26:26..but they also migrate because they are driven out.
1:26:29 > 1:26:33Well, that's great that we are able to break the news of your discovery
1:26:33 > 1:26:34in our film.
1:26:34 > 1:26:39You will appear in the acknowledgements of this paper!
1:26:39 > 1:26:43Oh! Well, I never thought I'd end up as a footnote in a scientific paper!
1:26:43 > 1:26:45That's fantastic.
1:26:48 > 1:26:52But just as suddenly as they appear, usually in May,
1:26:52 > 1:26:55Painted Ladies disappear in late October.
1:26:55 > 1:26:58For years, it was thought they simply hibernated,
1:26:58 > 1:27:02like many other British butterflies, but they don't.
1:27:02 > 1:27:05In fact, they don't stop doing anything.
1:27:05 > 1:27:08Feeding and breeding throughout the year,
1:27:08 > 1:27:12albeit on different continents, they are always on the move.
1:27:12 > 1:27:17As northern Europe gets colder, they seek warmer climes.
1:27:17 > 1:27:21And where better than where it all began - Morocco?
1:27:21 > 1:27:27Incredibly, a final generation makes the 2,500km journey
1:27:27 > 1:27:32from Britain back to Morocco in just a few days.
1:27:32 > 1:27:35And it's not just from here - they do so from wherever
1:27:35 > 1:27:38they have travelled across Europe each year.
1:27:38 > 1:27:40In six generations,
1:27:40 > 1:27:44Painted Ladies move up to 5,000km in one direction,
1:27:44 > 1:27:47towards the Arctic Circle,
1:27:47 > 1:27:49and 5,000km back to Morocco.
1:27:50 > 1:27:53In a truly remarkable voyage,
1:27:53 > 1:27:55they return to Africa
1:27:55 > 1:27:57to start their life cycle
1:27:57 > 1:28:02and the extraordinary migration all over again.
1:28:09 > 1:28:12We've learned so much about the Painted Lady,
1:28:12 > 1:28:14and there couldn't be more of a contrast
1:28:14 > 1:28:17between the lush green gardens here at Rothamsted
1:28:17 > 1:28:19and those rocky deserts in Morocco.
1:28:19 > 1:28:21But do you know, I think it's about time
1:28:21 > 1:28:24that we let these creatures go free.
1:28:24 > 1:28:27And there's enough food plants around here that they could breed
1:28:27 > 1:28:31and maybe even send a next generation of butterflies
1:28:31 > 1:28:34going back all the way to Morocco.
1:28:34 > 1:28:38Right, I think we should go for it, set the butterflies free!
1:28:38 > 1:28:40One, two, three, go!
1:28:40 > 1:28:43Oh, look, they've been trying to get out all day, I think.
1:28:43 > 1:28:46Fantastic, there we go.
1:28:46 > 1:28:48Morocco is that way, go!
1:28:48 > 1:28:49Yes!
1:28:49 > 1:28:52There we go. Oh, look, there we go.
1:28:52 > 1:28:54Be free!
1:29:12 > 1:29:13WINGS BEAT