All language subtitles for The Great Butterfly Adventure BBC 1080p HDTV x265 AAC MVGroup Forum EN Sub

Every spring, a tiny hero
of the insect world undertakes
a journey that almost defies belief.

Weighing less than a gram,

the intrepid Painted Lady butterfly
migrates a staggering 2,000 miles

from the Atlas Mountains in Morocco,
all the way to the UK and beyond.

Right now, across Britain,

hundreds and thousands
of butterflies

are arriving on our shores
after an epic journey.

I'll be following
that incredible journey

as it advances across Europe.

Painted Lady.

With the help of insect expert
Dr James Logan,

we'll be unpacking the science

behind a migration
of immense proportions.

That's amazing. It's actually
following your finger.

I'm going to be
charting the progress

of our butterfly spotters
from across the country

with the help
of this fantastic team.

Quick, quick, quick. Painted Lady.

And we have a dedicated army of
butterfly enthusiasts on the ground

helping us.

Working closely
with leading butterfly experts

and using hi-tech experiments
and the very latest science,

we're unravelling one of nature's
greatest migratory mysteries

and perhaps revealing
for the first time

the answer to the greatest puzzle
of all -

just why do they migrate
in the first place?

This is the story of the greatest
insect migration on Earth.

This programme contains scenes
of Repetitive Flashing Images.

Rothamsted Research Centre
in Hertfordshire

is the world's leading centre
in insect science.

Here, they unlock mysteries
from the insect world

with some quite extraordinary
technology.

So where better to track this year's
migration of the Painted Lady?

In their grounds, we've set up
a special butterfly hub,

which we're sharing
with more than 700 Painted Ladies,

so we can really get
up close and personal

with these extraordinary creatures.

Alongside our butterfly hub,

James has set up a communications
centre to chart their arrival.

All over the country,

the public are getting involved by
sending in their videos and pictures

as Painted Ladies appear in Britain.

She's the first one we've found
in the garden this year.

It's almost, like, magical
when you actually see one.

Painted Lady.

And I'm going to be doing
some incredible experiments

to unlock the secrets
of the Painted Lady migration,

finding out exactly how and why
they do what they do.

Got it.

Yes! Yes, I've done it.

Is that OK? That's absolutely right.
Brilliant.

This extraordinary migration begins

in the North African deserts
in winter.

After breeding
and building up their numbers,

they set off in spring,

heading across the Mediterranean
to Europe and into the UK

on a quite remarkable journey

for a creature as fragile
as a butterfly.

The Painted Lady story
is a fascinating one.

I came to love butterflies
through bees.

I kept hives for many years

and used to spot them
out in wildflower meadows.

Like most people, I'm enchanted
by their colours and variety,

but how many realise what this
one species manages to achieve?

The Painted Lady
is a pretty familiar sight

in most of our gardens,

which makes it easy
to take for granted.

So here's everything
you need to know

about these mini marvels
in just a minute.

Painted ladies are 5cm in length
and weigh a mere 200mg,

which is a tenth of the weight
of a paperclip.

Yet amazingly, they can fly
100 miles in a single day,

the equivalent of us
running four marathons,

and do so at speeds of up to 30mph.

They lay their eggs
on thistles and nettles,

the preferred food choice
for hatching caterpillars.

Painted Ladies
are a global phenomenon,

the most widely distributed and most
successful butterfly in the world.

They really are amazing creatures,
and supreme travellers, of course.

But why do they go on
such a long journey

and, actually,
a really dangerous one?

I've been to find out
where it all begins.

I've travelled over 1,200 miles
to Morocco in North Africa.

Flanked by the Sahara Desert
and Atlas Mountains,

Morocco is a dry
and unforgiving place.

It's early March,

and the Painted Ladies
have been busy

mating and laying eggs here.

Driving through
this incredibly parched landscape,

it's just so hard to imagine
that this is where the butterflies

that we see fluttering around our
green English gardens come from.

But they do. One man has
a special fascination with them.

Constanti Stefanescu is the world's
leading expert on Painted Ladies

and has been coming here
for many years to find them.

He's a Spanish lepidopterist
from the Natural History Museum

in Granollers, in Catalonia.

Constanti has had many scientific
papers published on the Painted Lady

and is working on his latest one.

Since I was a boy, I was very
interested in animals in general,

and butterflies in particular.

Well, the Painted Lady
is really a very special butterfly,

because it's one of the very few
that can move long distances.

So to understand the butterfly,

you have to deal with populations
moving between continents,

which is quite exceptional.

Constanti is piecing together

why Painted Ladies
fly from their breeding grounds here

to northern Europe each year

and is getting close
to a breakthrough

in understanding
why they make the migration.

I've come here to find out more
and to help where I can,

using essential
butterfly technology.

I've been issued with some
state-of-the-art equipment here.

And here we have what every
good butterfly collector needs -

a good old-fashioned...

..butterfly net.

OK.

I'm really hoping that we might
see some butterflies today.

Do you think there's any chance?

The weather
is very windy today, so...

It's not the best time
to catch Painted Ladies,

but there is still an opportunity.

The odds are against us - not only
is it windy, but it's also March.

Conditions are still good
for Painted Ladies,

but they're already
beginning to leave.

Migration is a risky business,
and many will perish along the way.

If there's somewhere which seems
safe and plenty of plants and so on,

why would they take the risk
of moving on

when so many of them die? Yeah...

Painted Lady. Ah!

Two. Two Painted Ladies.

One. Is it?

BLEEP, BLEEP, BLEEP!

There, there... Here.

Stop, stop, stop.

It was here. I think it went...

It was incredibly close.
I think I saw it go off that...

Oh, there it is, there it is.
Is that it?

Got it.

Fantastic! You got one.
I got one, yeah. Brilliant!

Brilliant!

So you see that they exist.

They do exist.

Can I touch it?

No, no. The wings not,
because the scales will be lost.

Oh, right, and you need those.
You only have to touch the body.

That's so brilliant
that you got one. Yeah.

How did you see that?
It's so tiny, that one.

Well, I am always thinking
about the Painted Lady,

so I saw the colour passing by

and the kind of flight
that these butterflies have.

What are you going to do now?

I will keep it in this envelope

and the wings
will be used for analysis.

That really was quite extraordinary

when Constanti just leapt off
cos he'd seen a Painted Lady.

It reminded me
of those great butterfly collectors

you see in old photos
with their nets,

determined to go anywhere
in pursuit of their prey.

I leave Constanti to it,
but I'll be back in the morning.

We'll be going on a hunt
for the Painted Lady's arch enemy

to gather vital evidence

which I hope will help us
understand the riddle

of why these butterflies migrate
in the first place.

When I left Morocco,
the Painted Ladies were preparing

to head off
on their extraordinary journey,

but how on earth do they know where
to go to once they leave Africa?

James has been trying to find out.

So how do our Painted Ladies
navigate

over such incredible distances?

Scientists here at Rothamsted have
been trying to solve that mystery

and, apparently, all you need
is a barrel, some glue,

a computer and, of course,
a Painted Lady butterfly.

Rebecca Nesbit is a scientist
with a passion for Painted Ladies.

She specialises
in butterfly migration,

and here at Rothamsted, she's part
of an elite entomology team.

For this experiment, first,
you have to prepare your butterfly.

This one has been in the fridge,
so it's... Nice and cold. Exactly.

Sleepy, easy to handle.

Get it out of the pot.

And butterflies

are really obliging.

If you just touch
the outside of their thorax,

they flick their wings down.

Oh, yeah.

And we can very gently
trap them on this sponge.

Just put this mesh over
so they're exposed like that.

This experiment is going to involve
attaching a Painted Lady to a wire

suspended in the barrel.

We're hoping to show
that Painted Ladies

work out which direction to go
when leaving Morocco

by using the sun as a compass.

But before this can happen, though,

you have to do something
rather bizarre.

Next step is to shave...

Shave the butterfly.
Shave the butterfly.

Just really gently
rub my finger across it.

OK, all right, so there's not

a mini butterfly razor blade,
then, that you use?

Which is what I was expecting,
I have to be honest.

Sadly not. It's a bit disappointing,

but just rub it away.

You're basically taking the hairs
off of the cuticle there,

just sort of
making a smooth surface,

presumably
so you can stick the glue on.

Exactly. This is just
normal contact adhesive.

Does it harm the butterfly?
No, not at all.

A tiny metal rod
is glued to the butterfly's back.

What are we hoping
to get out of this experiment?

What we're hoping to look at is
give the butterfly a view of the sky

and use the sun to find out
which direction it's going in,

so using the sun as a compass.

Painted Ladies
might be travelling vast distances

by taking cues
from the sun's position in the sky

and combining it
with the time of day.

To prove this,
we need to go outside.

This is the set-up, then. Yes.

So I think the first thing
we'll do...

I'll just show you
the flight simulator. OK.

Yeah. Or big white barrel.

So how does this work, then?

That rod we put on the butterfly...
Yeah.

..that will attach to this really
tiny bit of plastic tubing.

Once we put it on,
it is free to turn,

so the butterfly's flapping

and it can turn
in any direction it likes.

So it has to be able to see the sun

and then will orientate
when it sees the sun. Exactly.

It's a bit fiddly. Really need
a steady hand to do this.

I also need my glasses on.

Yes!

So what we need now
is to calibrate it,

so if you could just hold on
to the butterfly by the rod

and come in underneath
with a compass.

Can I use my phone compass?
Yes, please. Yes, that's perfect.

I'm holding my mobile phone

underneath this tethered butterfly
as a compass,

which is a little bit strange -
I've never done that before.

But the idea is we're going to see

where this butterfly heads
in relation to the sun.

Once I let it go, it should
take its lead from the sun

and fly in a northerly direction,
unless it wants to play a bit first.

Sometimes you can get them
to follow a finger.

That's amazing. It's actually
following your finger.

Why is it doing that?
I don't really know.

Its legs are out.
Maybe it is looking to... To land.

Yes. But, yeah,
they often do follow. Ah!

Are you sure
you haven't trained this one?

This is actually my pet butterfly!

With the butterfly ready,
it's time to do the experiment.

So the data's been fed in
from the barrel to this box,

and then what happens?

The information that
that box provides,

I'm then able to analyse it
and plot out the flight path

that the butterfly would have taken
if it wasn't inside the barrel.

These are some migratory
flight paths,

so you can see that these
are relatively straight.

So how does that tell you
how it uses the sun to navigate?

So what I can do is
I can compare a situation like this,

where it can see the sky,

with a situation
where I've put a lid on the barrel,

so the butterfly
can't see the sky. OK.

And by doing that,

you can tell whether
it's using the sun to navigate by?

Exactly. OK.

If it can't see the sun,
it doesn't know where it's going,

whereas when it can see the sun,
it's got a clear flight path,

then we know there's a difference.

The map on the left
clearly shows a Painted Lady

heading in the same
general direction,

whereas by blocking the sun,
the map on the right

shows the Painted Lady
moving in random directions.

So does this experiment
definitively prove

that the Painted Lady butterfly
uses the sun to navigate?

That's certainly what
our evidence is suggesting,

that when they can see the sun,
then they know where they're going.

If you put a lid on the barrel,

then they aren't going in
the right direction you'd expect

and, actually, they spin around a
bit more, they appear more confused.

What a really neat experiment,
demonstrating that the sun

is like an in-built sat nav
for our butterflies -

an essential piece of kit
for our Painted Ladies on the move.

They're getting very excited

by your experiment as well,
aren't they?

I mean, it's remarkable, isn't it,

the way that
they manage to use the sun

to travel these immense distances?

Yes, it is, and it's such
a simple experiment that we did.

We used a barrel and the sun,
essentially, to work it out.

But I couldn't quite understand
from the experiment...

So they're using the sun
for navigation,

but the position of the sun
changes all the time.

That's right,
so as the Earth rotates,

the sun moves against the horizon.

We don't actually know

how these butterflies
manage to compensate for that.

For other butterfly species,

we know that they have
an internal clock.

I mean,
we all have biological clocks.

Body clocks. Body clock, yeah.

These guys have a body clock
as well,

but it's in their antennae,
called a circadian clock.

Basically, what that allows them to
do is to tell what time of day it is

so they can adjust
their flight direction

based on where the sun is and
what time of day it is, essentially.

It's very clever. It is incred...

You think of these
as tiny creatures here,

and yet they have this highly
sophisticated navigation system.

Yeah, it's a perfect example
of evolution

in terms of how to overcome
adverse conditions

and make
the most incredible journey.

Every single one
of these butterflies

has the ability to do that
on its own.

I think these butterflies'
circadian clocks

are telling them
it's breakfast time.

They're having a bit
of orange juice, aren't they?

Back in March, Painted Ladies were
getting ready for their migration.

In part two
of my Moroccan adventure,

I caught up with them
before they left.

Early morning
in the Moroccan desert,

and the camels are already up.

It's late March,

the end of the Painted Lady
breeding season

and the start
of their incredible migration.

It's so windy here,

and if I'm having
to battle against it,

what on earth is it like
for a butterfly?

Yet that's exactly
what the Painted Lady does.

They fly over
this parched desert terrain

and right over those mountains there

to make it all the way to Europe
and, of course, to Britain.

I'm on my way to meet up
with Constanti Stefanescu again.

He's the most respected entomologist
in his field

and has had over 100
scientific papers published.

From environmental impacts
on butterflies

to population declines
and Painted Lady migration,

what he doesn't know about
butterflies isn't worth knowing.

Constanti's latest work is close
to revealing ground-breaking science

that will shed new light
on why Painted Ladies migrate.

He's collecting
Painted Lady caterpillars.

They're under attack
from another insect,

and it's the relationship
between them

that he's particularly keen
to investigate.

'To find a caterpillar,

'first you have to find
the plants they live on.'

This is one of the very good
host plants, isn't it?

Yeah, look,
there are many nests here.

Host plants
provide food for caterpillars.

Each species of butterfly
has a specific plant

on which they lay their eggs.

Are there plants
that the Painted Lady likes?

Yeah, in fact, the Painted Lady
is one of the few butterflies

that can use many different kinds
of plants,

even if they prefer these thistles
and the mallows.

What's that caterpillar doing now?

I see with the binoculars

that producing some silk
and, well, it's building a nest.

Once built,
the nest will form a snug tent

from which the caterpillar emerges
to feed.

As it grows, so too does the tent.

I'll just get
this little caterpillar here.

It's clinging on.

There, is that all right?
Not too damaged.

And there's another
much smaller one over here.

There we go.

It's astonishing to think
that this caterpillar,

once turned into an adult,
could fly all the way to Britain

and, who knows,
even end up in my back garden.

Collecting Painted Lady caterpillars
is easy when you know where to look.

A far greater challenge for
Constanti is what lurks within them.

He's looking for signs

that Painted Lady caterpillars
have been attacked, but by what?

So this is a mass of cocoons of
the main enemy of the Painted Lady.

It's a tiny wasp.

The adult wasp, what it does

is to search for the larvae of
the caterpillar of the Painted Lady

and lay the eggs inside the body
of the caterpillar.

Once they hatch,

the wasp larvae begin eating
the Painted Lady caterpillar

from the inside out,

eventually forming a silky mass
around the caterpillar corpse,

before finally emerging
as adult wasps.

I estimate that maybe 60%, 70% of
the caterpillars of the Painted Lady

are killed by this parasitoid.

But I can tell when you found that,

you were rather excited to find
these horrible creatures. Oh, yeah.

So what are you going to do
with this now?

I will keep this mass of cocoons
inside the vial,

waiting for the adults to emerge.

So our butterflies in Morocco

are under serious attack
from a deadly parasite.

It's the possible link
between the parasitic wasps

and Painted Lady migration
that Constanti's investigating.

One main part of the research

is to see how many
of these caterpillars will die

because of the parasitise
by the wasps,

and so every night,

we have to check if some of them
have already died or not.

So, actually, you're quite
interested if one's dead.

Yeah.
I hope that some of them will die.

A curious Constanti
is compiling his evidence.

He'll take the caterpillars
home with him to Spain.

The wasps they might contain

could be a key component
in his migration research.

I've got to go home soon,

but I can't leave without catching
at least one Painted Lady, can I?

This morning, I'm on a mission.

This is my last chance.

There's one here.

Yeah.

Ha! Got one!

Here's one. Oh, I'm so pleased!
I'm so pleased.

Yeah, this butterfly is more easy
to catch than a fresh butterfly.

Oh, come on!
It's my first Painted Lady.

What are you doing here?

Well, there it is -
my first Painted Lady.

And it's an incredible experience,

although I'm glad
I'm collecting it for science

rather than just for a collection.

Painted Ladies are definitely out
this morning, and my eye is in.

Oh, hang on, there it is.

Oh, yeah. Here's the Painted Lady.

Oh, no, no...

Is it still there? Yeah.

Yeah. Oh, yeah!

OK, your second Painted Lady. Two!

That's great. I know my technique
was a bit useless, but I got it.

I did get it. Number two.

Number two, yeah. But you see again,
this is a very, very old butterfly.

Show a bit of gratitude!
Stop saying it's old and rubbish.

Be pleased I'm doing your work
for you!

For free.
Thank you. Thank you so much.

It's been a really good day, no?
Yeah.

The adults...
I think it's time for a tagine, no?

Tagine - now you're talking.

We can celebrate the capture of the
Painted Ladies with a nice tagine.

Constanti managed to collect over
100 caterpillars in Morocco

which, depending on how many
develop into butterflies

and how many are killed
by the wasps,

could shed new light
on understanding

the Painted Lady migration.

Scientists like Constanti,
at the forefront of lepidoptery,

rely on centuries of research
by enthusiastic amateurs.

Many of their specimens

are now in the Natural History
Museum in London,

home to the largest collection
of Painted Ladies in the world.

This is my very own
private night at the museum,

with the echoing walls
now all the crowds have gone.

You normally think of dinosaurs like
Dippy at the Natural History Museum

but, actually, there are more than
30 million insect specimens,

as well as a whole load
of world-renowned experts,

so where better a place
to come than here

to find out more
about Painted Ladies,

those incredible flying machines?

Well, I'm really looking forward
to being able to find out more

about the kind of detailed anatomy
of the Painted Lady.

Dr Blanca Huertas
is the senior curator

of the museum's butterfly
collection.

There are over four million
butterflies here,

including Painted Ladies
from around the globe.

So is where they all are?

Yeah, this is the corner

in the world's biggest collection
of butterflies

where we have the Painted Ladies.

And how many Painted Ladies
have you got here?

We have probably about
3,000 specimens.

We have specimens
from all over the world in here.

Painted Ladies are found in more
countries than any other butterfly,

making them also
one of the most successful.

Just in these six, seven boxes,

we have specimens
from around 40 countries.

We've got things from Turkey,

we've got things from Morocco,
Sri Lanka...everywhere.

And what kind of time span,
then, do you have?

We've got collections
back into the early 1800s in here.

Do you notice differences
in the patterns?

Yeah, that's why we have
a long series of butterflies.

Some have differences,
say, not just on the upper side,

but also
if you look into the underside.

They're very distinctive.

They're very different to how they
actually look in the upper sides.

The rich colours are used
for courtship and camouflage.

Open wings display your wares
to other Painted Ladies.

Closed,
they blend in with the background

to help them avoid being eaten
by predators like birds.

Interestingly enough,

the females are much bigger,
and also kind of faded.

So sometimes
you see lots of butterflies,

kind of, really bright colours,
and they are only males.

The males are the ones
who are really, really bright.

The females
are a little bit more dull.

More dull, more faded?

Yeah. It's an expensive business,
in evolutionary speaking,

producing colour
with all of these pigments.

It implies a lot of energy.

So the females
need that energy in other things,

like giving birth
to the next butterflies,

to the next generation.

So the males still can afford it,

but the females are very careful
how they spend their energy.

So the males are expending
all their energy looking good,

and the females
are back at base, breeding?

Absolutely.

And if they don't do that,
they don't succeed finding a mate.

The males are the ones showing off,

and the females are usually the ones

who select those good-looking males
in butterflies.

Our fascination with butterflies
goes back centuries.

They were valuable and coveted
treasures back in the day.

Dr Hans Sloane
was an Irish-born scientist

and keen collector in the 1600s.

He amassed
one of the greatest collections

of plants and animals of his time.

His curiosities,
as they were known then,

are the founding core
of the museum's collections.

We're now in
the historical collections.

What an historical collection,
as well.

These incredibly big books.

The crown jewels, actually!

We've got the oldest specimens
of plants preserved in here.

But not only
the oldest specimens of plants

where I've brought you today,
because we have in here,

pressed in the herbarium sheets
of Hans Sloane,

we've got the oldest Painted Lady
ever collected and pressed

and preserved here
in the Natural History Museum.

The oldest Painted Lady?

Yes, we're going back
into the 1600s.

So even as his snap in time
with the plants,

this butterfly was flying around,

and we're going to see it
in a minute.

And this is part of this incredible
historical collection

which Hans Sloane started?

Yes, that was collected by himself

and preserved by
the Reverend Adam Buddle.

OK, let's go and see what
Adam Buddle had in his scrapbook.

Adam Buddle was a botanist
in the 1600s.

Amateur collectors were rife
in those days.

His vast knowledge of plants
meant his collections

were more respected and relevant
than most.

At the same time the naturalists
were collecting plants,

they also pressed some butterflies
in here.

This one in particular
is a very, very old specimen.

That's amazing. How old is that?

This was collected
back in the 1600s, late 1600s.

This is the oldest Painted Lady
we have knowledge of

and it's in here in the Natural
History Museum collections.

And did you know it was here?

It was kind of
a recent discovery for us

and it's very exciting to show you.

I can see that it's a Painted Lady,

and it's been pressed in the same
way that we'd press wildflowers.

Yeah. Pre-1700s, that was the method
to preserve specimens.

Collected flowers and plants

were pressed onto book pages
known as herbarium sheets.

Butterflies were preserved
with the flowers they feed on,

a practice that's still done today.

Look here. We have it written
in quite shaky handwriting -

"The Painted Lady".

They have a common name.
It's still in use after 300 years.

I just love looking at the detail
of all of this.

It's almost like
a work of art, this.

It's so beautiful,

the way he's placed the butterflies
in amongst the grasses.

That was preserved
by Reverend Adam Buddle.

You probably have heard about
the butterfly bushes, the buddleia.

Yes.
That's where the name came from.

Over many years, he compiled
a definitive English plant guide

that was never published.

The original manuscript
is preserved here.

In later years, the well-known
buddleia plant, or butterfly bush,

was named in his honour.

Do you know, all the time
that I've talked about buddleia,

I've got buddleia in my garden,

I didn't realise
it came from a person,

the person who, all those years ago,
collected these butterflies.

A great naturalist.

As you see, lots of care,
lots of notes and detail

on this collection - well preserved.

So a very important snap in time?

Absolutely.
Probably the only one, really.

It really has been so interesting

to come behind the scenes
at the Natural History Museum,

where they've been studying
butterflies for generations.

You know, insects are the most
successful animals on the planet,

and it's easy to see why Painted
Ladies fall into that category.

Back in March,

our Painted Ladies had been
breeding in Morocco in large numbers

ahead of travelling across Europe
on their epic migration.

The life cycle of the butterfly

is one of the most fascinating
in the natural world.

As Painted Ladies only live for up
to three weeks, they breed quickly.

When a male finds a female,
he has to win her affection.

To do this, he uses perfume.

Chemicals called pheromones

are intoxicating to females
at close range.

If she likes it,
they settle down to mate.

They stay locked together
for up to an hour,

sunbathing at every opportunity.

Eggs no bigger than a pinhead

are laid on plants
the caterpillars feed on.

Jewel-encrusted thistles glisten
for five days

before bursting into life.

Caterpillars gorge themselves
from the moment they hatch,

and begin to grow,

shedding their skin five times
before reaching full size.

In just ten days,

the caterpillar is a colossal 100
times bigger than when it hatched.

Suspended on a silk pad,
it splits its skin one last time,

revealing a case-like chrysalis
or pupa.

Inside the chrysalis,

the caterpillar reduces itself
to a DNA soup,

reconstructing
into something else entirely.

Two weeks later,
a Painted Lady butterfly emerges

and the cycle starts all over again.

We're following this year's
Painted Lady butterfly migration,

and our communications centre
is buzzing.

Piece by piece,
scientific experiments,

eyewitness accounts
and the world's leading experts

are helping us unravel the mysteries
of an extraordinary journey.

We know it began in Morocco

at the end of the winter
breeding season in March.

Our Painted Ladies then touched down
in Catalonia, in Spain, to refuel.

And this is where
I caught up with them next.

To get to Spain,

our Painted Ladies have had to
overcome extreme desert conditions

and to climb to incredible heights,

navigating mountains
as high as 13,500 feet.

Many will have died,
the voyage taking its toll,

or been eaten by predators.

An exhausted Painted Lady
is easy pickings for a hungry frog.

Those that do make it this far
are rewarded with better conditions.

These beautiful olive groves

just brimming everywhere you look
with spring wildflowers.

I mean, it couldn't be further away,
could it,

from the mountainous, rocky deserts
of Morocco?

But Catalonia is the first stop for
many of the Painted Ladies we saw.

It's 1,500km
from their breeding ground

and they're still only halfway
from their final destination.

I met up with Constanti

at the Granollers Natural History
Museum in Catalonia.

He's been studying the specimens
I helped him collect in Morocco

and I'm keen to discover
what he's found out,

but not before indulging my passion
for all things butterflies

with him first.

I love these old illustrations.

They're incredible, aren't they,
the detail on some of these?

Yeah, they are good indeed.

Painted Lady, Peacock.

Do you think it is there's something
about the beauty of butterflies

that makes people want
to study them?

Oh, yeah, of course.

There are many more people
that are attracted by butterflies

than by beetles, for example.

And you've got quite a few
collections here in the museum?

Yeah, and one of these collections

is my own collection
that I did when I was...

Is this yours?
Yeah, this is mine.

Here you are. Ah, gosh.

And, well,

it's very useful
to start a butterfly collection

to learn to distinguish the species.

Well, even I can get some of these.

OK, that's Peacock?

That's Peacock.
Red Admiral. Red Admiral.

OK, and if I haven't got
the Painted Lady by now,

you'd be despairing of me,
wouldn't you? Yeah.

Around the world, it's not
Constanti's beloved Painted Ladies

that get all the attention.

Until recently,

it was thought the Monarch carried
out the longest butterfly migration.

Travelling 3,500km
from the US to Mexico,

it often returns to the same trees
where its ancestors were born.

Thousands form a spectacular
butterfly blanket in the process,

which I've seen myself
in the Mexican forest.

The Monarch might be
a headline-grabbing superstar,

but it's not a patch
on the Painted Lady.

I'm amazed
by how much material there is

about the Monarch butterfly,

but really comparatively little
about the Painted Lady.

Well, I am quite envious

about how much has been done,
and is being done, on the Monarch

and the little research that
is being done on the Painted Lady.

But on the other hand,

it means that we still have
many, many things to explore

on the Painted Lady, which is nice.

But, actually, the Painted Lady
is the champion, isn't it?

I think so. I think...

Well, I know for sure

the Painted Lady
can fly more than 4,000km

in the whole cycle of migration,

and the Monarch
can do as much as 3,500km,

so at least the Painted Lady
can win the Monarch in this sense.

Constanti is trying to solve
a migration mystery

that's occupied his work
for the last ten years.

After numerous field trips
to Morocco,

collecting live caterpillars,

he's slowly unravelling the effect
a sinister parasite might have

on the Painted Lady migration.

So all those specimens
that you collected

in the heat of the Moroccan desert,
you've brought them back here,

and what have you been doing
with them?

I brought back all these larvae
until they pupate

or until they die because
they were attacked by the wasps.

I recognise the cocoon
from the caterpillars

that you showed me in Morocco.

And what's emerged
from that white mass?

Well, inside this mass,
there are many cocoons.

Very small cocoons.

And from each cocoon
will emerge one of these wasps.

These are sisters
that come from a single female

that lay the eggs
inside the caterpillar.

Are you telling me that all these
wasps came from one caterpillar?

From one caterpillar, yeah.

Gosh. Maybe there can be
between 50, 60, 70, depending.

It's almost as if each one of these

is then able to lay 50 eggs
in a caterpillar.

I mean, they could wipe out
the Painted Lady, couldn't they?

Yeah. In Morocco, we have seen

that most of the populations
of Cotesia, of these wasps,

are composed only by females.

They can reproduce
without the males.

So every single wasp
can parasitise, can attack,

and lay eggs
in a new Painted Lady caterpillar,

so the risk is terribly high.

A good Painted Lady breeding season

inevitably becomes an even better
one for the parasitic wasps.

Constanti believes
the wasps have a key role to play

in Painted Lady migration.

It won't be long before
he can finally reveal his findings.

Outside in Catalonia,
the Ladies are already here.

The ones who managed
to escape the parasitic wasps

are enjoying the Spanish sun.

So why is it you think

that the Painted Lady
has come to places like this?

Well, because here,
they find exactly what they need

to have a big success
for reproduction.

So you see that everything is green.

There are flowers everywhere,
there is nectar for the adults,

there are food plants everywhere.

But this lasts only a short period.

So the next generation
has to move to the north,

to track the same situation in
central Europe or northern Europe.

So it's the strategy
of this long-range migrant

which is the Painted Lady.

So not all Painted Ladies
fly to Britain in one go.

Many stop over somewhere like this
to feed and breed,

their offspring emerging hard-wired

to continue migrating
to Britain and beyond.

It's a relay race,

with one generation passing
the baton to the next, and so on.

Some, however,
emerge from a chrysalis in Spain

and don't migrate any further
at all, choosing instead to stay

and spend their short three-week
life breeding,

while food is abundant.

Their main food plant,
thistles, are seasonal.

As they die off in one country,
they bloom in another.

So it makes sense for
some Painted Ladies

to migrate and follow them.

Much of what Constanti
had shown me in Spain

involved the Painted Lady's
arch enemy wasp.

What he'd kept from me
was worth the wait.

So here,
I have some of the butterflies

that I raised from the caterpillars
that we collected from Morocco.

So these are all... Right, OK. OK?

One of the caterpillars
Constanti brought back from Morocco

didn't fall foul
of the Cotesia wasps

and instead went through
its full transformation

into a butterfly in his office.

Oh, yes, I can see them. Yeah.
The legs are moving.

That's a male, so we can release
this male at the hilltop.

Oh, great, OK.
Probably he will enjoy the place.

I'm very nervous about doing this,
because they're so delicate.

OK, all right. So, just...

OK, like this.

Just here, yeah?

Yeah? OK.

OK, that's incredible -
this butterfly,

which came from a caterpillar
we picked up in Morocco,

has never flown before,
and we're just going to let it go.

Off you go. Off you go.

Oh, look. He needs to warm
his wings up a little bit first.

Do you think? Well, I think
he is more or less ready.

OK, I'm going to let him...
You take your time.

A virgin flight is a big deal.

It's really fluttering.

Come on. Oh!

There he goes!

He's doing quite well, huh?
Not bad for a first flight.

A hesitant start, maybe,

but this butterfly
will be migrating north to the UK

alongside the others within days -

unless, of course,
it decides to stay and breed

for its short life instead.

So why are some Painted Ladies
driven to migrate and others not?

James is getting exclusive access
behind the scenes

here at Rothamsted to find out.

I've been given special permission

to get inside this high-security
facility here at Rothamsted

to find out some of
the latest cutting-edge research

on insect migration.

I feel quite privileged.

This is pretty awesome.

It's like being in a spaceship
in a sci-fi movie

or something like that.

It's also a little bit spooky.

But I believe this is where
the magic happens.

Here, they're studying
migratory moths

to understand what makes some
insects of the same species migrate

and others not.

The results should apply
to migrating butterflies as well.

What on earth is going on
in this experiment?

Well, we use a number of techniques
in our lab

to study insect migration.

And these are our roundabout-style

tethered flight mills.

OK, so roundabouts for moths?

That's right, yes. So, basically,
we use this technique

to investigate the flight capability
of different individuals

of the same species,

using this technique

to identify good flyers
and poor flyers

so we can try to understand
the genetic control of migration.

The moths on the roundabouts
are flying on their own accord.

It's their natural flight
driving them

and their every move
is being measured.

OK, so how do you define
a good flyer and a poor flyer?

Is it all to do with how far
they fly or...?

We place the moth
onto this roundabout

and then we just allow the moths
to fly overnight

and then those individuals
which have flown a long way,

which might be 30km
in a single night,

we can put into one category,

and then we might have others
that only fly a few hundred metres.

And why do they do that?

Why do you have some long-haul
and some short-haul flyers?

Some individuals
can be highly migratory

and others hardly move at all.

And they do this in response
to different conditions

that promote migration or not,
as the case may be. OK.

But something in the environment
or something can change

and trigger them
to become a long-haul flyer?

That is exactly what happens.

And so it might be
the environmental conditions,

the weather, it might be the quality
of the host crops

that they're feeding on.

That can turn them into a migratory

or it can turn off
the migratory genes.

What are those genes actually doing
physically to the insect?

How do they help with the migration?

Well, there's a whole number of
genes that are being overexpressed,

but some of them are evolved with
the availability of flight fuel

which, in these insects,
is body fat.

So a number of genes are associated
with turning fat into a fuel

that they can use.

There are also genes
which are associated

with the production of strong,
very active flight muscles.

And so, again, those long flyers,
they have the strongest muscles.

The genes associated with those are
turned up to maximum, if you like.

Wow. Does this apply
to other insects?

Whatever we learn here
would be perfectly transferable

to all butterflies and moths
that migrate

and so it would be relevant
to the Painted Lady story.

So, what this research is revealing

is that variations
in environmental conditions

appear to switch
certain migratory genes on or off.

Some are fatter, some are fitter,

some develop bigger flight muscles,
and so on.

Fatter ones with stronger muscles

are likely to continue migrating
to the next country,

while others are better equipped
to stay in one place and breed.

We are monitoring the 2016 migration
at Rothamsted,

and know that Painted Ladies
left Morocco in March.

By April, they were breeding
in Catalonia.

I came back from there

expecting them to be
navigating through France

and hitting our shores in early May.

May came,
but not many Painted Ladies.

Brutal weather in northern Europe
earlier this year

hit them from all sides.

So it's no surprise, then,

that the class of 2016
is late arriving.

In May and early summer,

northern Europe had its highest
rainfall for over 100 years.

Rising river levels threatened
to decimate towns in Germany,

Paris flooded and the UK
had one of its wettest Junes ever.

An average Painted Lady
weighs 200mg.

Large raindrops can weigh
more than 70mg.

So flying through rain
is virtually impossible.

Added to that,
butterflies need to warm up

in the sun to fly efficiently,

so bad weather is bad news
for Painted Ladies.

Back at Rothamsted,
the Painted Ladies in our hub

are making the most
of what we put out for them.

The butterflies love the sugar
that they get from the oranges,

and that's one reason
why they migrate,

why they go from Morocco to Spain,

is because the food plants dry up
in one country

and they need to move on
to find fresh plants,

like these here, the buddleia,

which you may have in your garden,
that the butterflies enjoy so much.

But not all of them travel up
through the western Mediterranean.

Some head east instead,
as we are going to see.

When Painted Ladies leave Morocco,

they don't all head one way
to northern Europe -

some embark on a route
to eastern Europe instead.

Each year, the different routes
have varying degrees of success.

Through April and May this year,

great numbers descended on Corfu
and Crete via the eastern route,

but comparatively few arrived
in northern Spain and Britain,

due to bad weather.

By expanding their distribution
across different routes,

the butterflies breed successfully
in enough countries

to keep their overall numbers up.

While some emerge from their cocoons
and continue migrating,

others emerge and do not travel on,

staying instead to breed
a further generation.

That is why we see
more and more Painted Ladies

as the summer progresses.

In the communications centre,

James has been mapping the progress
of our Painted Lady migration

as it has unfolded.

What have you been looking at?

Well, I'm just mapping out
the routes, actually,

of some of these butterflies.

You started off here, didn't you,
in Morocco?

South of Marrakech,
really near to the Sahara desert.

Of course, they can start off
pretty much anywhere

across this Northern African belt,
here, and sort of head northwards.

Let's draw this out.
So, you started about here

and then you moved up to Catalonia,
didn't you?

Yes, it's the kind of north
of Spain.

Imagine being the size
of a butterfly

and having to fly that far.

You'd think it would take
a long time, but actually,

scientists have modelled it
and they reckon that it could take

as little as 20 to 36 hours.

That's with a tailwind, obviously,

and then flying at an average
of 15km per hour.

And then they head on, they just
carry the drive northwards?

That's right. So, the ones
that you saw in Catalonia

probably will make their way,
or already have made their way,

or are starting to make their way,
up here.

But over here, on the other hand -

let's do this in another colour,
cos it seems to be a second route,

certainly with the sightings -

the butterflies seem to be
heading up perhaps from Libya, here,

maybe the coast of Egypt,
up to Crete.

So lots of sightings in Crete
and other parts of Greece, as well.

So, this seems to be
a bit of a hot spot this year

with our butterfly spotters.

I love the idea that there are
these butterfly enthusiasts

who are sitting there,
waiting in their gardens

for the arrival of the Painted Lady.

The eastern route,
having benefited from good weather

throughout the year,
is reaping rewards,

and none more so than Crete.

So, Crete has been
an absolute hot spot.

Let me prove it to you, actually,

because one of
our butterfly spotters

has sent us in a video, and...

This is from a guy
called David Cook,

who is on holiday in Crete
at the moment,

and he sent in this footage
of Painted Ladies.

Hi, I'm Dave Cook,

I'm holidaying on the Greek island
of Crete.

It's a bit like a motorway service
station for butterflies.

I've never seen so many
Painted Ladies in one place!

Actually... So, he's counted them,

and there's between
50 and 100 per bush.

That's amazing. He's only ever seen
one or two in the UK,

so he's booked this holiday
to Crete,

hoping that the Painted Ladies
were going to be there,

and lo and behold they were.

So, he's ditched his family,
they're on the beach.

They're on the beach
just, you know, having a holiday.

He's out butterfly spotting for us.
Yeah. It's brilliant.

I'm feeling a butterfly divorce
coming on, you know.

That's exactly what I would do
on holiday. Really?

Absolutely, ask my wife.
I'm not going on holiday with you!

THEY LAUGH

Coming out of such
a horrendous June,

it's no surprise
our British spotters

didn't have as much luck
as Dave Cook in Crete.

So how can scientists detect when
Painted Ladies do arrive in the UK?

James has the answer.

Now, we know that thousands
upon thousands

of Painted Lady butterflies

make this incredible journey
every single year,

but it's not as if we see them
sort of flocking past our heads,

and that's because they do it
in a rather efficient way.

I like to think of it
as the insect highway in the sky,

flying at these incredible heights,
at these incredible wind speeds,

and these things can survive this.

It's actually amazing.

And the way that scientists
know this is by using this -

the vertical-looking radar.

It might appear little more
than a satellite dish,

but as the old saying goes,
never judge a book by its cover.

'Insect migration expert
Dr Jason Chapman

'is the custodian of this
cutting-edge piece of kit.'

So, this dish is basically
reflecting a beam up into the sky?

That's right, yeah. It's like
shining a searchlight into the sky.

Basically, we're hoping that insects
will pass through that beam

so we can detect them.

It's kind of a cone shape
as it's going up in the sky.

Yeah. So, it's a very narrow cone.
It just spreads out a little bit,

but by the time
it gets to our highest altitude,

which is 1.2km,

it's still only 30 metres wide,

so it is quite a narrow sliver

of the sky that we're sampling.

On a sunny summer's day like today,

we might expect maybe two, three,
four...5,000 individuals.

Thousand?! Yes.

'Different insect species
fly at different heights.

'Painted Ladies pass through
the beam at a much higher altitude

'than most butterflies.

'But it takes more than just
the height they fly at

'to confirm they're Painted Ladies.'

The reason
that we can identify and classify

different kinds of insects

is because
they're different shapes and sizes

and their different
wing-beating frequencies

produce very different signals.

So, when you see a butterfly
in the sky with the radar,

how do you know
it's on the migration?

When you see hundreds of individuals
flying over on the same day

in the same direction,
then you can see that there must be

a population-level migration
going on.

For us to see what
the vertical radar sees at altitude,

we need to go inside.

So, this is the computer that
controls the operation of the radar.

As insects passes through,
we'll get a peak

as an individual
flies through the beam. Oh, yeah.

Yeah, so you can see
the peaks happening.

They're quite quick,
just within a couple of seconds.

This graph represents
a Painted Lady butterfly?

That's right. It's a signal
that we recorded from a Painted Lady

flying over the radar.

So, that peak tells you
how big the insect is?

Yes, so the magnitude of the peak,

the amount of power
that is being reflected,

that will give you some indication

about the overall size
of the insect.

OK, and along this bottom axis,
we've got time,

and it's three seconds here, or so.

So, within a couple of seconds,
that insect, of that size,

passed through the beam.

That's right. And so in two seconds,
it passed through our beam,

which is about 20 metres' diameter.

Yeah, yeah. So a very quick
calculation tells you

that it was travelling
at ten metres per second,

that's about 40kmph.

This one clearly was on the move.

Yeah. Must have been part
of the migration.

Incredibly, they do so at heights
of over 1,000 metres.

Only one type of butterfly
travels north in large numbers

and at that height
this time of year,

so they can only be Painted Ladies.

Maps from previous years
provide confirmation.

Each of those black bars

is related to the numbers
of individuals

that were flying in that direction.

And that's what we would expect
during the early spring migration

as these butterflies
are travelling northwards.

If the Painted Ladies
were not migrating north,

the map would look
something like this.

Multidirectional flight paths
indicate an insect

with no particular place to go.

I've had an insight into what is
normally a completely hidden part

of the Painted Lady butterfly's
migration and its world.

It's allowed scientists
to unravel and unlock

some of the amazing secrets
of this incredible migration

that these tiny, fragile
butterflies make.

When our Painted Ladies
do finally arrive,

they're going to need refreshment.

So, how can we prepare
for their arrival?

Long-distance athletes
need regular refuelling,

otherwise it affects
their endurance.

And, you know, it's exactly the same
thing with Painted Ladies.

When they come here
after that monumental journey,

they're hungry - they need nectar,
sugar, for energy.

And there are all sorts of things

that we can do in our own gardens
to help them.

Patrick Barkham
is going to show me how.

Patrick is a natural history
journalist and author.

He's so obsessed with butterflies
that in the space of one year,

he tracked down
every British species for a book.

He's turned his Suffolk garden
into a wildlife haven.

Why is this so particularly good
for butterflies?

Well, it's very simple, really.
I've planted some

typical wildflower mixes.

I tried to find mixes
that use native species to Britain,

not just exotic mixes.

It looks like a sort of
fairly scruffy lawn, to some eyes,

but there's loads of
grass-feeding butterflies

that actually lay their eggs,

the caterpillars feed
on the grasses.

Then, of course, you chuck in
a load of wildflower mix

and you get these lovely wildflowers
on which the butterflies can nectar.

And you've got
some fantastic daisies here.

These are great,
and these surprised me,

because I saw 19 Painted Ladies
on these a couple of weeks ago,

just round the corner.

So the Painted Ladies come in
on this enormous journey

and it's seen my ox-eye daisies

and it's dropping down to refuel,
you know, it's a lovely thing.

And then I went to look for them
the next day

and they'd all disappeared again,

so they'd all continued
their journey north.

All that effort - you've planted
these fantastic wildflowers,

and then they just disappear!

They race through your garden
in 30 seconds

and have a quick fuel stop
and then zoom off again.

To me, that's great
and that's enough,

but the next thing is you want them
breeding in your garden.

You really want their food plant,
thistle,

and thistle
is not such an easy sell, is it?

No. I've got these enormous thistles
by my front door.

It's quite hard, isn't it,

to ask keen gardeners
to let thistles grow?

It's a real struggle -
even I struggle with thistles.

This is a lovely example of how
if you do something for butterflies,

it helps all kinds of wildlife,
cos I found another caterpillar,

and it's somewhere
on this plant here,

and it's the caterpillar
of an Angle Shades moth.

I took a little picture of it

and, helpfully,
someone identified it for me.

And it's this wonderful insect,

and the caterpillar
comes out at night

and munches away at the thistle

and soon it will pupate and become
this beautiful, beautiful moth.

Patrick's garden
is full of low-maintenance plants

that we can all easily grow
in our own gardens.

So, got some buddleias here,

and some slightly smelly
garden gloves.

Oh, don't worry, they can't be any
worse than mine, I can promise you.

And there is a trowel
and some spades

and here's our buddleias.

'I'm not averse
to a bit of gardening,

'and I'm keen to lend Patrick a hand
replenishing his butterfly oasis.'

So, where do you want me to start?

So, I'd just stick one
at the back of the lavender -

more or less where that spade is
would be fine.

OK, great. You can dig out these.
These are just little weeds.

Don't get stung by the nettles

that I've left there
for the small Tortoiseshells.

Do you know, my garden is...

I've left a lot of nettles
for butterflies

but, blimey, they do spread,
don't they? Yeah, they do.

I really love the idea that
you can look out in your garden,

you can see that
you've got nettles and thistles

and things like that,
and you can think,

"I'm not a lazy gardener,

"I'm doing something
that's incredibly moral,

"I'm saving butterflies."
Yeah, exactly.

So, are you happy for this
to go in here? Yeah, yeah.

Buddleia is by far the most popular
nectar plant of British butterflies.

A favourite of 18 species,
including the Painted Lady,

it's not called the butterfly bush
for nothing.

I just took these from cuttings,

and I just literally take
a cutting of buddleia,

stick it in a pot like this,
leave it for a few months

and then you get a buddleia

and you don't have to spend £10
at a garden centre for one.

It's really important to think about
plants that will keep going

right through the year,

particularly when there aren't
so many other flowers around.

That's right. The nectar sources
at the end of the summer,

when everything else has died back,
they are the real key.

Butterflies in the garden are
a marker of a healthy ecosystem.

Get things right for them, you get
things right for other wildlife.

The value of caterpillars
as a high-protein food source

for breeding birds, for example,
is invaluable.

Butterflies are also
effective pollinators.

When feeding, pollen sticks to hairs
that cover their body

and is passed from flower to flower.

But they're in decline.

Industrial agriculture, habitat loss
and changes to the weather

have seen the numbers drop
by 70% in recent years.

Anything we can do for butterflies
in our gardens

might help buck the trend.

The butterfly flower I wanted
to show you, Martha, is this.

Ivy? Yeah. OK.

One of the best things you can have
for butterflies in your garden.

It flowers really late
in the season, doesn't it?

Yeah, and that's perfect for
the butterflies like the Red Admiral

that need energy late in the summer
to hibernate through the winter.

The other thing that's brilliant,

this is another great thing
for the lazy gardener, isn't it?

I guess it is.
THEY LAUGH

All around Patrick's garden
is a one-stop butterfly buffet.

So, this is garlic mustard,
or jack-by-the-hedge.

This is a weed you'll see
under almost any hedgerow,

and it is the food plant
for the Orange Tip.

If it has butterflies on it,

then it becomes
a really beautiful thing.

Yeah, and it becomes a precious
thing, and you start thinking,

"Well, I'd better not cut that back

"because there might be
a butterfly egg on it,"

and it does start making you think.

With the UK
now basking in summer sunshine,

conditions are perfect
for Painted Ladies.

And after such a long wait,
they've finally made it here.

They will be hungry,

and with flowers up and down
the country in full bloom,

Painted Ladies made it just in time.

It took a while,
but in late June, early July,

the class of 2016 eventually hit
our shores in significant numbers.

Around the country, our spotters
are on a winning streak.

Marie and David Law
found their Painted Lady

on the busy streets of Skegness.

Turn the right way round!

We have two today. Two?
Two Painted Ladies.

Tell me facts about
Painted Lady butterflies.

They fly from Morocco.

Well done.

Yeah? Go on. To here, some of them.

OK, they fly from Morocco.

Yeah. Through Spain.

Yeah. Through France.

Sometimes, yeah. Then here.

Yeah. Or they can fly
straight from Morocco to here. Yeah.

Come to me, butterfly,
land on my hand.

Oh, wouldn't that be nice?
It would!

Marie and David have a knack

for being in the right place at
the right time for Painted Ladies.

Oh, look, it's one of the...

Oh, no, there's one there.
Yeah, there is.

Very top. Right here.

Oh, another one.

Painted Lady butterfly, definitely.
It's definitely a Painted Lady.
Definitely.

It's not a Cabbage White. No.

Go on, run up and see.

Is it a brown one? Is it...?

No, it's not, it's a Speckled Wood.
Speckled Wood, yeah?

That was a Speckled Wood.

Last year, they witnessed something

even the most experienced
butterfly scientists

would be lucky to see.

We're at Skegness Gibraltar Pond
nature reserve. Yeah.

We're here... We...

THEY LAUGH

We are here because in June,

we saw two Painted Lady butterflies
that were just about to mate.

It was one of those moments where
you just happened to walk about

and you just notice that one
little thing that is different,

just that one...

They were acting a bit unusual,

that's not normally
what butterflies do,

and then you take a close look
and, "Oh, there are two of them."

There's two of them here.
They could be just about to mate.

They were very close.

He was... He was getting closer
and closer and closer to it

and then they just flew off.

They landed together,
I got some shots, both flew off,

came back to exactly the same spot.

They did. Which means that was
probably the male's territory.

Just right there. It was down here.

Back at Rothamsted,

butterfly migration specialist
Rebecca Nesbit

has worked with
an incredible piece of kit

that could help us understand
what Painted Ladies get up to

now that they're here.

To do this, she tracks Painted Lady
flight patterns using radar

and is going to show James
how to do it.

Hi, Rebecca. Hello.

So, tell me, how on earth
do you put a radio antenna

onto the back of a butterfly?

So, first we have to trap it down.

As with the flight simulator
experiment,

you have to shave a Painted Lady
before attaching anything to it.

Rebecca showed me earlier,
so now it is my turn.

Here is your butterfly. Yeah.

Oh, no, no! Is that OK?

Oh, no. Come back!

Yeah, give it a go. Got it.

It's quite a lively butterfly.

Oh, now, you can do this. Behave.

There we go. Oh, no.

This is embarrassing.
I've made such a mess of it.

Yes! Yes, I've done it.

I handle insects all the time,

but I don't know why my hands
are completely shaking,

and I think because you did it
so professionally,

I'm so nervous about doing it badly.

If you think about it too much,
your hands definitely start shaking.

OK, brilliant.

'A gentle rub and my first
butterfly haircut is done.'

Once glued on, this tiny radio
antenna weighs almost nothing.

What it lacks in size,
it makes up for with what it can do.

This technology is the creation
of Dr Jason Lim,

one of the world's leading experts
in insect tracking devices.

Called a harmonic radar,

it is able to pick up the antenna
attached to the Painted Lady's back

using a specific wavelength.

It's then able to track
the Painted Lady as it flies.

So, does it come off eventually
or...?

It will just fall off
after a few days.

This may look heavy,

but it's extremely lightweight
and harmless,

and doesn't affect
the Painted Lady's ability to fly.

Butterflies require energy to fly,

so topping my one up beforehand
is a good idea.

Unravelling the proboscis
takes not only skill

but a willing participant.

The proboscis
is a long, narrow tube,

a feeding straw designed to get deep
into nectar-rich flowers.

In this instance,
sugar water on a cloth will do.

It takes a while,

but we do eventually
get the butterfly to eat something.

Having had its pre-flight meal,

my butterfly
is now ready for takeoff.

And we are heading out
to that release box. Yeah.

And then, if it's OK, if you could
just whip the string off... OK.

..and that lets the butterfly
go free.

Conditions are good.
Absolutely perfect,

particularly when the sun comes out.

Well, this one seems OK.

Perfectly happy, looks quite calm.

We put the pot
right down on the floor...

Yeah. Tip the butterfly out
and then I will close it.

Gosh, she's really active now,
isn't she?

Yes, that heat
has instantly brought her out.

As the sun comes out,
so do our Painted Lady's wings.

Acting like solar panels,

they absorb sunlight
to warm up flight muscles,

ready for action.

With my butterfly poised

and Jason Lim's tracking radar
spinning into action, we're ready.

DRAMATIC MUSIC PLAYS

OK, you can release
the butterfly now, over.

Excellent. OK, he's ready.
He's ready? Great. He's ready.

OK, stand back. Stand back.
Just so we don't shade it.

OK. And the sun is out.
How perfect is this?

Quick. And I just pull? Yeah. Pull.

MUSIC STOPS SUDDENLY

'I obviously peaked too early.

'Taking this chance to sunbathe
while it can,

'my Painted Lady
needs a little encouragement.'

Fly, come on!

The sun is out.
Oh, it's going away again!

Fly, come on!

And then she's off.

Jason, the butterfly is on the move.

OVER RADIO: 'OK, over.

'Butterfly is moving quite fast.

'It's now flying towards
the manor garden, over.'

My Painted Lady stops for a refuel.

Back in the van, Jason tracks it
as it moves around Rothamsted.

The radar can keep tabs on it
from up to a kilometre away.

So, where's our butterfly?

That is the butterfly
flying from here,

so it is moving slowly.

Yes, that's the one.

This is a 100-metre ring.

So we know the butterfly
is 100 metres away from us.

Away from us. Yeah? Yes.

So, here is our release point.

OK. So we can see
the butterfly has flown

about 50 metres away from there.

So it's on the move,
then, clearly? Yeah.

That's brilliant
that we're able to see this.

It's stopped now, though.
Yeah, so we just have to wait.

Maybe it's just foraging
below the radar, under the radar,

where the radar
couldn't pick up a signal from it.

OK. So the machine allows us
to track the position

of the butterflies
every three seconds.

So the butterfly could do
what they normally do -

sunbathing to warm up the body

and then they forage, flying around
different patches of flowers

and potentially
looking for a mate as well.

What a great piece of technology
this is,

allowing us to see into the life
of the Painted Lady butterfly.

And who knows what the future
might hold for this?

It might even allow us
to unlock even more secrets

of the Painted Lady
butterfly migration.

Tracking technology
will no doubt advance

and so too the distances
that can be covered.

You never know -
one day, we might be able to track

a Painted Lady all the way
from Morocco to here.

Our butterfly spotters
don't need tracking devices.

Now that it's July,
Painted Ladies are coming to them.

Dave Cook is back from Crete
and out doing what he loves best.

I've come here to the location,
Brixton Common,

with the specific intention
of finding the Painted Lady

that I found here this morning.

She's still here
and she's still nectaring.

It's great.
It's absolutely brilliant.

Result.

What it's all about.

And Darcia from Wiltshire is
equally pleased to be out and about

spotting her favourite butterfly.

I am Darcia Gingell and this is
Morgan's Hill nature reserve,

which is a Wiltshire
Wildlife Trust site

in North Wiltshire.

And it's a gorgeous morning
this morning,

and we're here to hopefully
try and find some Painted Ladies.

It's actually quite difficult to get
hold of a picture of a Painted Lady

unless they're actually still
and nectaring,

because a lot of the time,
they're quite fast flyers,

so they'll zoom into view,
maybe come around you,

circle round you, take a look at you
and then they're off.

Unless you find them,
as I've said, nectaring.

Once they're in one place,
maybe on a nice thistle,

they tend to stay there,
and you might even, you know,

get a chance to take a glimpse
of one for a few seconds,

and they're off again.

Quite a big butterfly there.

No, small Tortoiseshell.
Got my hopes up.

About a week ago, me and my partner

were at a place
called Ravensroost Wood.

Just walking along the track,
next minute, "Whizz!"

Round your head.

Really shocked and surprised to
actually see it was a Painted Lady.

Just came and landed and settled
on the floor in front of us.

It's a beautiful butterfly.

So, there we go.

It's just flown along behind us
and come and landed and settled.

It's quite fascinating

to think where this
beautiful butterfly has come from.

I think it's almost, like, magical
when you actually see one,

and I think it reminds you
of those fairy tales

when you were a child

and you're imagining what a fairy
really would be like,

and I think a butterfly
is the closest you can get to that.

With Painted Ladies now being seen
all over the country,

how do we know just how successful

the migration has been
this year overall?

'Richard Fox is part of
Butterfly Conservation,

'a definitive authority
on British butterflies.

'His migratory maps
tell a fascinating story.'

Your volunteers have been
looking out for the Painted Lady,

which, of course, we're following.

Yes, so we've got some maps here

of sightings of Painted Ladies
from this year.

So, each Painted Lady picture
represents a place

where members of the public have
reported seeing Painted Ladies.

And this is from...
January and February?

I'm amazed there are any
Painted Ladies at all!

Exactly. So, you often really
wouldn't see any Painted Ladies

in Britain at all over that January,
February period in a normal year.

But this year wasn't normal.

We had a very, very mild spell
over New Year

and winds from the south,

bringing Painted Ladies
from North Africa,

where they normally are
at that time of year.

These pioneering Painted Ladies

coming up into southwest England,
South Wales...

But not just the south,
I mean, there's Isle of Man,

Northern Ireland.

Some in Cumbria as well.

So really amazing influx
at that time of year.

Painted Ladies normally
start arriving here in May.

But a very warm January
meant one bucked the trend.

They react very quickly
to conditions around them.

Tropical air blowing in from Africa

saw Britain bask
in unseasonably warm weather

at the beginning of the year.

With the warm winds came
the first Painted Lady sighting,

in Somerset in south-west England,

as early as January 3rd this year.

It had flown the 2,500km
from where I was in Morocco

to here in a matter of days.

But that's not the earliest
on record.

Remarkably, one was spotted
on New Year's Day in 2013.

Painted Ladies that fly here early
in a single journey

are known as pioneers.

Unfortunately,
these pioneers will perish

once the weather turns cold again.

And then we come on to the spring,
a few more.

Yes, there were a few more,

but the weather
really wasn't very good this spring.

It was colder than usual,

it was very wet in some places.

So although we're seeing
more butterflies,

as you'd expect,
there's nothing very much going on.

So, we move on to the next one -
the summer.

And what a summer, albeit delayed.

In late June through July,

sightings erupted
across the country.

So, these are Painted Ladies

not coming direct from North Africa,

but coming up from Spain,
Portugal, southern France.

It's an explosion of Painted Ladies.

There's barely a part of the country
that doesn't have Painted Ladies.

That's right, and indeed,

even the places
where they haven't been recorded,

they may well have been there,
just not been spotted by people.

These Painted Ladies
aren't coming from North Africa,

as the ones in January
and February were -

these are moving up
from southern parts of Europe,

so they're kind of a generation on.

But, really, all over the country,
as you can see.

Yeah, the far north of Scotland -
out in the Hebrides.

Really good concentrations

down in the southwest.

We had people on the Isles of Scilly
and in west Cornwall

who saw, you know, 50 or even 100
Painted Ladies in a single day,

so there were some quite good
numbers around at this time.

So we hear so much
about the kind of problems,

the troubles that butterflies
are in.

What about Painted Ladies?

Well, Painted Ladies
are a very adaptable species.

They are obviously highly mobile,
they are nomadic,

they don't live
in particular places,

and most importantly, I guess,

the food
that their caterpillars need

is mainly thistles, in this country,

that's mainly what the caterpillars
are eating

and, of course,
they're very common and widespread.

So, actually, Painted Ladies
have done really well

in Britain over the past 40 years.

Oh, that's really good to hear.

To get here, Painted Ladies started
out from Morocco in late March.

Following the appearance
of the foods they feed on,

they arrived in Spain in April
to breed,

a new generation carrying out
the next stage of the journey

through France in May.

Few made it to Britain in May,

bad weather delaying their arrival
in significant numbers

until late June, early July.

The Painted Ladies we see now

are the grandchildren
of ones that left Morocco.

Generations born in this country

will then continue to push
further north towards the Arctic

before the summer is out.

Basking in the British sunshine
in July,

Painted Ladies are a welcome sight.

This is what our spotters
have been waiting for.

Like Dave and Agnes in Dorset,
who found a beauty.

It's very colourful. Yes!

You can see how fresh she is, she's
got that metallic glow on her.

Yeah, she's only been out a day.
If not this morning.

Fantastic.

THEY CHUCKLE

The numbers
are definitely starting to build.

She is warming up really nicely,
isn't she? Yeah. Brilliant.

Dave and Agnes
are just the tip of the iceberg.

Spotters from all over the country
are seeing our Ladies regularly now,

and the pictures are rolling in.

People have been sending
all sorts of pictures -
not all butterflies!

But this is a really good one.

And do you know what? This is a guy
called Adam Middleton,

and guess what.

He's only 14 years old. That's...

The image is so sharp. Isn't it?
You can really see the antennae.

It is absolutely brilliant.

You can see the eye here,
the antennae,

and it's got its proboscis out,

it was obviously trying to feed
on nectar there.

It's really hard
to get a picture like this

of a butterfly in the wild.

And he's 14 years old,

so not only is he a fantastic
butterfly spotter,

he's a pretty good photographer
as well.

Here's a young man who will be
after your job one of these days.

LAUGHING: Yeah, probably.

It's so important
that people do this.

You know, scientists are relying on
data from people that are, you know,

doing all of this,
taking pictures, sightings,

so that they can record them and see
what is happening with the migration

from a conservation point of view.

What I like is the way
that people have been doing it

in our country
for hundreds of years,

so we have the best biological data,
don't we?

That's right.
We've been doing it for so long.

We're a nation
of butterfly spotters.

All the Painted Ladies
our spotters are seeing

are this year's
Moroccan descendants.

When I joined the world's leading
Painted Lady expert,

Constanti Stefanescu,
earlier in the year,

he was piecing together the puzzle

of why Painted Ladies migrate
in the first place.

It's taken him ten years
of extensive research

to establish the facts
and reach a definitive conclusion.

After countless expeditions
to Morocco

and painstaking data analysis
in Spain,

what has he found out?

Well, the butterflies
are going absolutely crazy in here,

and it's rather perfect for us to be
able to welcome Doctor Constanti.

It seems a long time ago

since we were filming together
in Morocco, doesn't it?

Yeah, yeah, it's far away.

But they clearly found you
as a butterfly fan.

Now, tell me about your discovery

and all the work
that you've been doing,

which I was happy to be a part of.

Well, I started to collect
caterpillars of the Painted Lady,

to see which were its natural
enemies, many years ago,

maybe ten years ago.

Immediately I realised that these
wasps can be very, very important.

And then I thought that maybe
migration could be...

..a way to escape this mortality,
to these little wasps.

Constanti's research indicates
that Painted Ladies leave Morocco

at a specific time of year
to escape from their deadly enemy,

the Cotesia wasp.

If they don't, they die.

When I collected the caterpillars
in Morocco,

I was afraid that maybe the results
would not support the idea.

But when I brought back
these caterpillars to Catalonia,

immediately they started to die
because of this parasite.

So, yeah,
I am very happy about that.

So, how would you sum up
your discovery this year?

Well, I would say that the data
that we gathered this year

is the first clear demonstration

that natural enemies
is also one of the factors

that are important for migration.

Still analysing some data,
but the results are very clear,

so I am absolutely confident
about what we have found.

Constanti has cracked it.

'His ten-year investigation
has revealed astonishing new facts

'about the Painted Lady migration.'

Yes.

'Tiny wasps are the Painted Lady's
nemesis in Morocco,

'laying eggs inside caterpillars

'and subsequently killing them
on a grand scale.'

As Painted Ladies breed,

so too do the wasps,
in huge numbers.

At some point
during the breeding season,

Painted Ladies have to leave Morocco
to survive.

This is ground-breaking news,
a scientific first for Constanti.

His dedicated research has paid off

and added another reason
why Painted Ladies migrate

in the first place.

Not only do they move
to follow their food source,

as previously known...

..but they also migrate
because they are driven out.

Well, that's great that we are able
to break the news of your discovery

in our film.

You will appear in
the acknowledgements of this paper!

Oh! Well, I never thought I'd end up
as a footnote in a scientific paper!

That's fantastic.

But just as suddenly as they appear,
usually in May,

Painted Ladies disappear
in late October.

For years, it was thought
they simply hibernated,

like many other British butterflies,
but they don't.

In fact,
they don't stop doing anything.

Feeding and breeding
throughout the year,

albeit on different continents,
they are always on the move.

As northern Europe gets colder,
they seek warmer climes.

And where better
than where it all began - Morocco?

Incredibly, a final generation
makes the 2,500km journey

from Britain back to Morocco
in just a few days.

And it's not just from here -
they do so from wherever

they have travelled across Europe
each year.

In six generations,

Painted Ladies move up to 5,000km
in one direction,

towards the Arctic Circle,

and 5,000km back to Morocco.

In a truly remarkable voyage,

they return to Africa

to start their life cycle

and the extraordinary migration
all over again.

We've learned so much
about the Painted Lady,

and there couldn't be
more of a contrast

between the lush green gardens
here at Rothamsted

and those rocky deserts in Morocco.

But do you know,
I think it's about time

that we let these creatures go free.

And there's enough food plants
around here that they could breed

and maybe even send
a next generation of butterflies

going back all the way to Morocco.

Right, I think we should go for it,
set the butterflies free!

One, two, three, go!

Oh, look, they've been trying
to get out all day, I think.

Fantastic, there we go.

Morocco is that way, go!

Yes!

There we go. Oh, look, there we go.

Be free!

WINGS BEAT