♪♪ GIAMATTI: If you had never seen a butterfly, you might not believe they were real.

They are so colorful, they can't help but be noticed, and so fragile that being noticed should spell their doom.

Yet butterflies are truly among nature's most surprising survivors... taking on unique powers of flight.

From a dark and dangerous past... butterflies have triumphed in almost every place the planet.

They are masters of deception and seduction, and they're indispensable to much of life on Earth.

This is the story of how butterflies have become one of the great wonders of the world.

♪♪ ♪♪ ♪♪ GIAMATTI: We don't really know where the name 'butterfly' came from.

The origin of the word is lost to time... And in many respects, butterflies themselves are a mystery.

But we do know they are remarkable.

There are butterfly stories from every culture.

One Chinese legend turned two tragic lovers into butterflies some 1,600 years ago.

And that's what they've come to symbolize most -- transformation... metamorphosis... the ability to abandon an earthbound body... and take to the air on gossamer wings.

Squint into a midsummer meadow in bloom.

It's as though the flowers can fly.

♪♪ ♪♪ But what if we followed not our imaginations, but real butterflies into the worlds they actually live in?

What would we see then?

How did these incandescent creatures come to be?

♪♪ In the wilds of Mozambique, Africa, a team of scientists are tracking down the story of how butterflies began.

They've come to Gorongosa National Park, one of the world's great centers of biodiversity.

♪♪ Armed with the tried and true tools of the collection trade, the team tries to get a sense of all the butterflies that live here.

♪♪ MAN: Oh!

Ho ho ho.

♪♪ GIAMATTI: Akito Kawahara of the Florida Museum of Natural History studies the evolution and diversity of invertebrates.

Especially of moths and butterflies, a vast group called the Lepidoptera.

KAWAHARA: In Mozambique, we see all kinds of new species all the time and we're also sampling butterflies to try to get an idea of when butterflies evolved and came about.

We still don't know much about them at all.

♪♪ GIAMATTI: It's thought that the Lepidoptera arose as flowering plants began to flourish across the planet.

But there are so few traces of these delicate creatures in the fossil record, Akito can only discover their origins by looking at the ones alive today.

Yet, he can still step deep into the past... in the primal darkness of the African night.

♪♪ ♪♪ The very air is thick with life.

These are creatures from an ancient world.

♪♪ ♪♪ Akito and his team are attempting to reach back into the story of the butterfly's older cousins -- moths.

MAN: [ Chuckling ] A mantis. There's a mantis.

KAWAHARA: There's a mantis on the lens here.

MAN: I know.

KAWAHARA: 160,000 species of moths described so far and probably 500,000, maybe a million species in the world.

We are just, just beginning to understand what's happening.

This is a moth we want. We want to cup that.

This is a white pyralid. This is a white crambid.

GIAMATTI: From the astonishing gathering of insects drawn to the lights, he handpicks the characters he's interested in.

KAWAHARA: This is a noctuid... about 150 maybe, 200?

GIAMATTI: Moths are primarily creatures of the night.

The key to their connection with brightly colored butterflies may lie in the predators that are also drawn to this midnight swarm.

Bats.

BARBER: They're hunting up high.

WOMAN: Yeah.

GIAMATTI: The bats have brought Jesse Barber of Boise State University here tonight.

He's an expert on the ecology of sound.

Together, Jesse and Akito are investigating how a predator and its prey shape each other.

BARBER: We're trying to figure out how bats are driving moth evolution.

There's a bat. Is it in view?

WOMAN: Yep, Yep, right through the space.

BARBER: Nice!

GIAMATTI: As fast, insect hunting bats course through the air, Jesse and his team record what we cannot hear -- the sounds of bat sonar.

[ Bats squeaking ] The recordings are slowed down to a frequency within our range.

[ Bat squeaking ] Flying with mouths open, the bats generate high-speed sound signals from their larynx, 'seeing' with sound waves and echoes.

Pinpointing the moths' locations, the bats scoop them up in a catcher's mitt-like membrane that stretches between their feet.

♪♪ Then Jesse's ultrasonic microphones pick up something more surprising -- moths sending out their own signals pitched at the same frequencies as the bats' sonar.

♪♪ BARBER: To try and understand which moths are making ultrasound back at bats, we bring them into a lab setting in the field and play echolocation calls back at them and try and understand who makes sound.

[ Squeaking ] We then have to figure out why, and we know form lab work back at our universities in the States that part of the reason they make sound is to jam sonar.

Rolling.

GIAMATTI: Jesse and Akito are attempting to unravel millions of years of a sonic arms race we've never been able to hear.

Bats hunting with sonar, moths fighting back by jamming it.

BARBER: These moths are actually screaming at incredibly high intensities back at bats.

[ Squeaking ] Oh, my gosh!

Wow! Turning the gain down.

Lots of sound!

GIAMATTI: While there are still so many mysteries to solve, Akito and his team of collaborators have made an extraordinary breakthrough.

Using DNA sequencing, he is tracing the genetic origin of all the butterflies we've identified.

Remarkably, they all share a single ancestor -- a tiny brown moth that fled the night some 50 million years ago, driven, perhaps, by the rise of bats relentlessly hunting the dark skies.

In a world full of light, moths burst into color.

We call these daytime fliers butterflies, but they are really some 20,000 species of colorful moths that have spread across every continent except Antarctica.

♪♪ ♪♪ ♪♪ The most cosmopolitan of all is the painted lady.

♪♪ She can be found throughout Europe, from India to Asia, from North into South America, and all across Africa.

♪♪ With its bright splashes of orange, her body is both beautiful and alien... and it's equipped with keen butterfly senses.

The tips of her legs can 'taste' the leaf she stands on.

♪♪ Her eyes have more than 30,000 lenses.

Instead of a nose, she has antennae that catch the faintest scent.

And she hears with membranes in her wings.

Our painted lady isn't just resting with wings folded, she's listening for danger.

But one of her most remarkable features is what we think of as a tongue -- a proboscis.

It's made of two long strands that zip together to form a tube.

She usually carries it coiled, just below her head.

♪♪ [ Birds chirping ] ♪♪ To eat is to drink, so a butterfly simply uncoils her proboscis, and with the aid of a micro-pump inside her head, pumps liquid nourishment up into her body.

♪♪ And it's not just nectar they're drinking.

They can imbibe all kinds of beverages from lots of different surfaces.

Sap from tree bark and mineral-rich waters from sand banks and tidal edges.

Some even sip the blood, sweat, and tears of various hapless neighbors.

♪♪ Being able to mop up many liquids has helped butterflies thrive all around the world.

And what's been good for butterflies has been very good for all the plants they feed on.

♪♪ Flowers prepare for butterfly visits.

They make nectar to offer a meal, but it's actually a form of seduction.

The real takeaway is pollen, the agent of procreation.

Pollen resembles a sticky powder, and as the butterfly sips from the flower, its proboscis can't help but pick some up.

But the butterfly doesn't seem to mind... or even seem to notice that its proboscis is encrusted with pollen.

It coils it up in the usual way, and it's off to the next flower.

♪♪ ♪♪ The plant is counting on the butterfly to bring its pollen to flowers of the same kind, completing a sexual connection the plant needs.

♪♪ That's how the birds and the bees -- and butterflies, too -- have helped plants reproduce for a very long time.

♪♪ But then, there's the intriguing case of the flame azalea tree.

♪♪ Flame azaleas are native to the Appalachian Mountains of Virginia, and from late spring to midsummer, it's easy to see how they got their name.

All along the high ridges, bright yellow to blazing orange blossoms burst out like signal fires, unmistakable beacons to pollinators far and wide.

But while the flowers are showy and obvious, just how they are pollinated is not.

[ Birds chirping ] Mary Jane Epps of Mary Baldwin University reveals that the mystery lies in the flowers' unusual architecture.

EPPS: So, one of the really cool things about flame azalea flowers is the way the reproductive parts are situated.

So, you have the petals, which are fused into this long tube, and the nectar is actually born down at the bottom of that tube.

And here, we have the anthers, which are the pollen-bearing part of the plant.

And sticking even farther out of the flower -- and you'll notice it's sort of curved at a slightly different angle often -- is what's called the stigma, that's the female reproductive organ.

And so, for pollination to occur, which, of course, is required for fruit to set and seeds to form on a plant, you have to have pollen deposited on this stigma.

[ Buzzing ] There are lots and lots of different insects that come to flame azaleas -- various bees, butterflies, flies, even beetles.

Noticing a lot of these bees would gather lots of pollen but never make contact with that stigma.

So, we started wondering who actually does the pollination here.

♪♪ GIAMATTI: The flower's design foils even a large eastern tiger swallowtail as it comes for a drink of nectar.

EPPS: So here's a swallowtail... coming right in to this azalea.

GIAMATTI: Then Mary Jane discovered the telltale fingerprints a butterfly leaves behind.

EPPS: Wow. All of these have butterfly wing scales on them.

GIAMATTI: As the butterfly drinks, its wings constantly brush against the anthers.

The faintest touch pulls out a chain of pollen, like a party streamer... and with another wingbeat, deposits some on the sticky stigma.

Pollination has begun!

This discovery was a true surprise.

It's just the third case of wing pollination ever recorded.

But as the swallowtails flutter from tree to tree, it appears their wings have become an essential partner in the sex life of the flame azaleas.

♪♪ ♪♪ ♪♪ A painted lady has her own offspring to create... and lays dozens of tiny eggs of a surprising blue.

♪♪ ♪♪ Each egg is attached to a leaf with a special glue that keeps it in place at any angle.

♪♪ They are jewel-like and almost microscopically small.

She clusters them on leaves the babies will be able to eat when they hatch.

And that's the end of her motherly duties.

♪♪ But in just five days, a little caterpillar begins to break out of its shell.

♪♪ ♪♪ The eggs were only the size of a pinhead.

The baby caterpillars are smaller than a grain of rice.

♪♪ Even the plant hairs sprouting from the leaf are giant obstacles for them.

♪♪ Almost nothing about this little caterpillar resembles its parents.

With 8 pairs of legs, a black spiky suit, and no wings at all, it's an entirely different animal.

♪♪ And its whole world is confined to its host plant.

And so it eats.

The more it eats, the faster it grows, and thus begins a life of one transformation after another.

Little painted ladies will transition through 5 stages called instars, building a new body each time.

Every stage is a mini metamorphosis as hormones trigger ongoing changes in the caterpillar's body.

But unable to fly away, they're an easy target.

♪♪ A young blue jay, no longer being fed by its parents, can make a good start on its own with helpless little caterpillars.

♪♪ ♪♪ ♪♪ But some caterpillars are able to fight back.

A monarch is already set on an elaborate course of self-defense.

The milkweed it feeds on is full of noxious chemicals, and the caterpillar will store them up and become noxious, too.

Some caterpillars are so toxic, they can make their predators really sick.

These plump, juicy-looking characters are busy weaponizing black cherry leaves into a version of hydrogen cyanide.

♪♪ All across the butterfly kingdom, 20,000 species known so far, 20,00 different caterpillars parade.

♪♪ ♪♪ Some glow a leafy green... others wear elaborate disguises... or simply taste terrible.

♪♪ This one tries looking like a snake!

♪♪ Sometimes, it's hard to see what look they're going for.

♪♪ Others just look disgusting... like bird droppings... or even an unappetizing fur ball.

♪♪ ♪♪ It's all to give them a chance to eat and not be eaten.

It's a problem they face all their lives.

So if they carry their noxious chemicals into adulthood, they want their predators to know it.

♪♪ That foul-tasting monarch caterpillar passes its milkweed toxins on to its butterfly form.

Predators learn quickly not to eat it.

And so its cousin, the queen butterfly, has converged on the same look.

It, too, feeds on milkweed and tastes just as bad.

By looking so similar, it doubles down on the warning signal the monarch sends to predators.

But some butterflies get away with a bold-faced lie.

This highly toxic pipe-vine swallowtail is loaded with plant acids.

Its beautiful markings are copied by the black swallowtail... and a dark version of the eastern tiger swallowtail.

It's very hard to tell them all apart, and that's precisely the point.

Two of them are perfectly good to eat... but they're hoping to scare predators away simply by looking like their poisonous cousin, the pipe-vine.

But whether your colors are true or false, you can't fool all of the predators all of the time.

Butterflies are such an important prey for so many creatures, they live in constant danger in every field and forest.

♪♪ When you're surrounded by enemies, it good to have an ally.

From deep in the Peruvian Amazon, a report has surfaced of some strange behavior between a butterfly and one of the most formidable creatures in all the rainforest.

They're organized, disciplined, relentless, adaptable.

The collective power of ants is enough to intimidate anybody.

But Aaron Pomerantz, a PhD student at the University of California, has come to Peru to follow up on a startling account of a butterfly braving such an army.

POMERANTZ: So a collaborator of mine, his name is Phil Torres, he noticed that there were these butterflies that were sort of hanging out with ants on bamboo stalks, which was kind of odd because ants usually treat butterflies as they would anything else.

They'll attack them.

They'll, you know, use them as a food source.

GIAMATTI: The bamboo itself is an important part of the story.

POMERANTZ: From what I've been reading, not a lot of things eat bamboo.

It's really tough, you know, old, woody cellulose.

GIAMATTI: But Aaron began searching for just the right young stalks and made a fascinating discovery.

Tiny ants swarm all over the ends of the stalks, drinking a sugary nectar seeping from the tips of the shoots.

♪♪ POMERANTZ: At the base of the bamboo there are these leaves.

So, as I pulled one back... Oh, we got caterpillars!

...there were ants hovering over them, and I thought, oh, man, this might be the first time anyone has ever seen the larval stage for this butterfly.

GIAMATTI: Aaron had uncovered a story that was new to science.

He had discovered the unusual life cycle of a butterfly called Adelotypa annulifera.

Its tiny caterpillars are doted on by ferocious ants.

♪♪ POMERANTZ: Oh, very cool.

GIAMATTI: Then, Aaron noticed that the caterpillars, too, were drinking the bamboo sap, all the while under the protection of the ants.

POMERANTZ: if we actually tried to get in there and handle the caterpillar, the ants would attack us.

You know, whether you're a parasitoid wasp, or a bird, or a human, these ants are going to protect them until their last breath.

♪♪ GIAMATTI: The caterpillars earn this security service by producing a sweet nectar of their own from the bamboo sap.

It's highly nutritious and rich in energy, and the ants mob the caterpillars to gain access to this special brew.

♪♪ But what of the butterflies?

How does this story end?

Aaron sets up a time-lapse camera focused on the tip of a bamboo shoot.

POMERANTZ: The butterflies are very rare.

They're very skittish, so it could be that our presence is preventing them from coming by, but we're going to let this sit and take an image every set half hour or so.

And, if we're lucky, maybe the butterfly will come by.

♪♪ ♪♪ Ah, there we go!

GIAMATTI: Left undisturbed for hours in the rainforest, the camera has captured a glimpse of these most remarkable butterflies.

They, too, come to bamboo to sip the nectar in a rare instance of butterflies and their caterpillars relying on the same food.

The nectar appears to fuel their entire lives.

And amazingly, the ants allow it.

It's the only example we know of where ants and butterflies feed together.

And look closely at the butterfly's wings.

Red spots grouped in threes may be mimicking the ants and doubling the butterfly's defenses.

Instead of a butterfly, a bird might look down and see nasty, stinging insects, while the ants, looking up, see a reassuring version of themselves.

With or without bodyguards, a caterpillar's job is to store up enough energy to undergo one of the greatest rites of passage in all of nature.

♪♪ A painted lady has reached her last instar and finally stops eating.

She spins a bit of silk, attaches herself to a stem, and hangs head down.

Underneath her final caterpillar skin, she is once more creating a new body, but this time, it's stunningly different than the 5 bodies she has made before.

♪♪ ♪♪ When she finally wriggles free... she is no longer a caterpillar at all.

She has become a chrysalis, a butterfly pupa.

Her new shape is already a blueprint for the creature she will ultimately be.

But now she's in the midst of a transformation so radical, science is still attempting to decipher how she does it.

Her outer skin dries and hardens.

For most of the next two weeks, the dull casing of skin looks dormant.

But inside, special cells send out instructions that complete a miraculous metamorphosis.

♪♪ ♪♪ ♪♪ Then... suddenly... she splits that skin open and is born again as a fully formed butterfly!

♪♪ She seems surprised by her unfamiliar body.

How strange her new extended legs must feel.

♪♪ Her head now has large, complex eyes.

Her jaws have been replaced with a long proboscis.

Its two unruly strands must be zipped together, and she struggles to get them under control.

♪♪ And now she has the ultimate in new parts -- wings!

Slowly, they unfurl.

♪♪ ♪♪ ♪♪ Finally, she takes flight, joining a new cohort of butterflies trying out their wings for the very first time.

♪♪ And the way they fly is unique.

♪♪ Butterflies have such large wings for their size, they contract their entire bodies to move them.

♪♪ They lurch and flop around, big wings laboring through the air.

Their flight may look awkward, but none of it is a mistake.

They are so maneuverable, and their flight plan so erratic, they're very hard for predators to catch in the air.

Their large wings act like an enormous rudder, enabling a change in direction with almost every flap.

♪♪ They hover by stroking back through the swirling wake they just created.

♪♪ They often clap their wings behind their backs, squeezing out a jet of air to push themselves forward.

♪♪ Despite what it looks like, they fly with complete control.

♪♪ ♪♪ Now they can feed on nectar.

But a butterfly doesn't go through metamorphosis just for a new kind of food.

If caterpillars were made for eating, butterflies are made for mating.

Caterpillars are just juveniles, unable to breed, their lives limited to a leaf or two.

Now they are adults, and wings open up a world of possibilities.

They compete... and flirt... dancing in the air... circling skyward in a butterfly ballet.

♪♪ ♪♪ When they do mate, they join at the abdomen, facing away from each other.

♪♪ ♪♪ How long they stay together varies widely from couple to couple.

Incredibly, some partners stay joined for hours.

♪♪ But not long after they part, the female must find the right host plant on which to lay her eggs.

Painted ladies are able to choose among a hundred different plants their caterpillars will eat.

Adults can survive on nectar from thorny acacia trees.

And that brings their story here to the edge of the great Sahara Desert in North Africa.

♪♪ This harsh, remote landscape in the Anti-Atlas region of Morocco is more of a moonscape than a butterfly garden, but it's the starting point of a butterfly tale so astonishing, it's hard to believe.

STEFANESCU: [ Speaking foreign language ] Hey, hey, yes!

This is a...well, a very, very old painted lady.

When you see one butterfly like this, you have to think what happened during his life or her life.

Because you see all these wings that are so broken?

So it's really a mystery what happened to this butterfly.

GIAMATTI: Constanti Stefanescu of the Natural History Museum of Granollers has come from Spain to unravel the painted ladies' remarkable story.

Intriguingly, the first to appear here in the fall are already at the end of their lives.

They have to be coming from someplace else.

So Constanti analyzed stable isotopes of hydrogen in their wings to identify the region where the butterflies were born.

The results were a revelation.

These worn and torn painted ladies, he discovered, had undertaken an impossible journey, some arriving in Morocco from as far away as the Arctic Circle.

Their amazing feat of flying and endurance begins as the cool, wet winter in the desert turns to a hot, dry spring.

Host plants and nectar sources begin to wither.

Painted ladies suddenly depart, turning north with an urgent purpose, looking for fresh food for themselves and their caterpillars.

After crossing the Atlas Mountains, it's a short hop from Morocco to Spain.

But painted ladies even farther south departed months ago from the tropical edge of the Sahara, riding warm African winds all the way across the desert and the Mediterranean Sea.

They arrive in Rome, Marseille, and Barcelona, and seek out some much needed nectar.

Then they mate and lay eggs.

In six to eight weeks, a new generation picks up the baton and continues north.

They cross the Alps, fly up the Rhine, spreading all throughout Europe, stopping to create new generations all along the way.

By the end of summer, they finally reach high into Scandinavia... and then suddenly disappear!

What happens next has been one of the long-standing mysteries in natural history.

No one had ever witnessed the return flight south of the painted ladies.

They simply flew to the north and vanished.

It was long thought they all died in the autumn.

But Constanti Stefanescu knew that somehow they were returning to Africa.

So he turned to Jason Chapman of Rothamsted Research in the UK.

Jason studies the emerging field of aeroecology -- how animals travel up in the atmosphere.

♪♪ This green drum-like apparatus is Jason's Vertical Looking Radar.

It sends pulses of electromagnetic waves straight up, 4,000 feet into the sky.

♪♪ Any insect, bird, or bat that flies through its beam will bounce a signal back to the dish.

CHAPMAN: Okay.

GIAMATTI: But to interpret what the radar sees and physically confirm which animals are up in the atmosphere, Jason and his team send aloft a series of aerial nets attached to high-flying balloons.

CHAPMAN: Well, the really exciting thing about the new field of aeroecology is that we now have the tools that can allow us to figure out how insects are using wind currents or being affected by wind currents to carry out their migrations.

Are we up?

♪♪ ♪♪ GIAMATTI: The sampling goes on day and night, and as the nets go up, they recede into a sky so vast, it seems an impossible task to measure and understand what's going on up there.

But Jason and his radar and nets have revealed an unimagined global highway and solved the mystery of the vanishing butterflies.

At any given hour, thousands of feet above our heads, there are literally trillions of insects riding the winds.

Among them are millions of painted ladies.

As autumn arrives high in Northern Europe, and their resources are running out, painted ladies do disappear.

They launch themselves into prevailing winds 1,500 feet above the ground.

Guided by internal compasses set on the sun, they begin to stream south, flying at 30 miles per hour and up to 300 miles a day.

Though these butterflies have never been there before, they are returning to the land of their ancestors.

If conditions are good, this one generation will reach Africa in a week.

Millions will continue flying south, across the Sahara to the tropics.

From Africa to Scandinavia and back, painted ladies will have travelled some 9,000 miles, 3,000 miles farther than their famous cousins, the monarchs.

They are champions of distance and altitude, completing the longest migration of any insect ever discovered.

♪♪ Many are bound for Morocco, where Constanti Stefanescu and his team have been waiting for them.

He can only imagine what they've been through and how such a small, fragile creature has accomplished such an enormous feat.

♪♪ STEFANESCU: This is a very old painted lady that has been attacked by a bird, probably.

But she's still visiting the flowers and trying to obtain food.

Hmm.

That's a male, a migrant that has come probably from Europe.

In a one hour or so, he will start to defend territories and try to obtain a mate.

♪♪ GIAMATTI: And so, as one butterfly's story comes to an end, another's is just beginning.

Painted ladies pass their torch on in a never-ending journey... from butterfly... to egg... to caterpillar... to chrysalis... to butterfly... in a ceaseless cycle of transformation.

♪♪ They are both ephemeral and eternal.

And perhaps that's what we see when we look at real butterflies... delicate but enduring heroes in the long game of life.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪