♪ Narrator: For every plate of food we eat, a third was provided by an unseen army of workers... tiny but powerful pollinators.

Jessica: Pollinators are animals that move pollen from one plant to another.

Sometimes they do this in exchange for a reward from the plant, like nectar.

Sylvana: Pollinators come in all shapes and sizes-- bees, flies, butterflies, beetles.

Ummat: Pollinators are essential for flowering plants.

If flowers don't get pollen, they won't produce seeds or fruits or all of these substances that we enjoy but also that so many ecosystems depend on.

Narrator: Through foraging and feeding, pollinating insects bring the fields into flower, and life depends on the fruits of their labor.

Dino: Some of the most precious food items we can think of-- chocolate, coffee, all of the fruits and nuts-- some of the most nutritious food items we depend on all come about thanks to the insects.

Narrator: Over millions of years, pollinating insects have developed complex life cycles... [bat screeching] and clever defenses to survive.

But across the world, they're now facing unprecedented threats.

Dino: Butterflies, bees, the pollinators that we're so concerned about, we are seeing in some parts of Europe and some parts of the temperate Northern Hemisphere that certain groups of insects are just simply disappearing.

Gavin: If we lost all native pollinators, our food sources could be threatened.

We would be looking at a restructuring of the ecosystem at an unimaginable level.

Narrator: Pollinators are at risk of vanishing, and with them, all the color, food, and life they bring to the planet.

Sylvana: Without them, it'd be a very colorless and bland world.

If you love to eat and you love pretty things, we need pollinators.

[Insects buzzing] [Bird chirping, wind blowing] Narrator: Across the world, butterflies have long been prized as symbols of beauty and transformation.

But it's unclear whether these adaptable creatures will be able to keep pace as the planet itself transforms around them.

[Vehicle running] Akito: I've been collecting butterflies in this area for many, many years.

Every time I come back to Japan, I try to come here and see what's here and what's not, and get an idea of what's changing.

♪ I've been looking at butterflies and moths since I was a little kid growing up in Japan, and I've never really stopped.

My specialty is butterflies and moths.

There are over 160,000 species in the world, and I'm really fascinated by all of them.

They do practically everything.

They come in all kinds of different colors and sizes.

There's so many questions.

Every time I look at an insect, I wonder, What is it doing?

What is it thinking?

♪ So this one right here is a fritillary butterfly.

These butterflies pollinate nettle, which is a purplish flower that's very common here.

And when we're looking for butterflies, we try to focus on that plant, because it's a very good place to find butterflies.

This one is a species that's found in the Mount Fuji area and this particular kind of habitat.

It's really nice to see this here.

Narrator: Here in the shadow of Mount Fuji, the butterflies bring a message that something is changing.

While some familiar species are nowhere to be found, a few newcomers signal a change in the environment.

Akito: This is a northern kichou.

It's called kichou because it's a yellow butterfly.

It's a little worrisome because they are not really supposed to be here.

And what's happening is, most likely because of temperature change, these are southern species that are moving northward from the south.

It's surprising to see some butterflies that I had not seen here at all when I was a child.

Narrator: The intrusion of southern species points to how a warming climate is triggering a shift change in the environment.

As temperatures rise, hardy survivors move north, while some resident species die out.

Akito: Talking to some colleagues, they've told me that some species are declining by about 50% from the previous year, which is significant.

Just to think about that is, it's kind of eye-opening.

Narrator: In Japan, like the rest of the world, insects are in danger.

But unlike anywhere else, here, a deep appreciation for bugs has long made them a cornerstone of culture.

Akito: I grew up half my life in Tokyo in Japan and the other half in the United States.

And that childhood experience allowed me to be exposed to the culture of insects in Japan.

Insects are really loved in Japan in so many different ways.

You can buy beetles in department stores and just grow them yourself.

A lot of Japanese poetry, a lot of literature.

This is something that's been going on for a long time, and it's deeply rooted in the history.

Narrator: In a world where bugs are widely considered pests, Japan's culture of bug appreciation starts at an early age at places like an insect hotel, a retreat for insect enthusiasts.

Akito: We're at the Pension Suzuran, which is a special bug hotel in Yamanashi Prefecture in the central part of Japan.

My father brought me to this insect hotel because he was interested in making sure that I would learn about insects.

[Indistinct conversations in Japanese] [Akito speaking Japanese] Akito, voice-over: When I was a little kid, I actually really didn't like bugs, and my father thought that was a problem.

And to get me excited about nature and understanding what nature means, he thought it would be great to bring me to places like this.

[Boy shouts in Japanese] And it was really an amazing experience just seeing other children like myself looking at insects and just getting excited about it.

Akito: So right now, we're showing the kids these stag beetles, which are very popular in Japan.

These kids love it, and they're not scared of them at all, they're just picking them up.

They all want to keep them, actually.

They asked me if they can take them home.

♪ At this hotel, there's a lot of parents that show their kids what insects are.

It's really kind of magical and really interesting to see both the parents and the kids excited about it.

♪ [Speaking Japanese] [Akito laughing] So now I live in the United States and I have two kids, and it's very important for me to bring them back to Japan to show them this culture that exists.

Loving insects is a wonderful thing.

[Speaking Japanese] [Laughter] This is a...

The Chryso... Chrysozephyrus.

Chrysozephyrus.

I've never caught this butterfly in my life, so I'm very excited.

There's still things to find, even at my age.

[Laughter] It brings back so many memories.

When I was a kid, my dad and I used to go look for these butterflies.

[Laughs] Narrator: Not long ago, the seasonal abundance of butterflies was simply taken for granted.

There seemed to be little need to collect scientific data beyond appreciating their beauty.

Now even an amateur childhood collection is a treasure of detailed evidence, and an invaluable window into the past.

[Speaking Japanese] Akito: My collection that I have here in Japan is something that I started with my dad when I was about eight years old, right about the age of my daughter right now.

My dad and I would go collecting, and we'd come back, we'd look at all the specimens, and we'd try to identify them and so forth.

[Speaking Japanese] Akito, voice-over: The collection itself has grown quite a bit.

I don't know exactly how many specimens are in there, but it's probably around 10,000 specimens or so, I think.

[Speaking Japanese] Akito: National butterfly of Japan.

Akito, voice-over: My collection has a lot of scientific value, but it has more a personal memory, and it's more like a diary to me.

I can remember where I was, what I was doing, who I was with, what the weather was like.

[Speaking Japanese] Akito, voice-over: It's unfortunate that a lot of the insects that used to be very common have disappeared.

What's happening, essentially, is that for many different reasons, mostly human-driven, the insects are not what it used to be.

So I think about my children a lot, and what is their future going to look like.

And I think that this is something that we all should be thinking about, and how we can change this.

Narrator: The disappearance of butterflies isn't simply a cause for nostalgia.

It's the vanishing of a natural workforce critical for the survival of flowering plants and all life.

Gavin: Pollinating insects are one of the most important assemblages of insects out there.

Without these pollinators, many of the plants can't sexually reproduce, they can't produce seeds.

Narrator: Rooted in the ground, plants can't travel to find a mate.

Instead, they need tiny animal partners to move pollen, their genetic material, to fertilize other flowers.

[Buzzing] To enlist the pollinators, the plants offer a sweet reward of sugary nectar and protein-packed pollen.

Insects like butterflies and bees have evolved along with flowers to be perfectly engineered for the job.

Flowers developed nectar tubes to fit the probing proboscis of their insect partners.

Akito: What's important is that a lot of times the flower has evolved a particular morphological shape that is a lock-and-key system with that particular moth or butterfly.

And so if you lose that butterfly or moth, that plant can't actually be pollinated, because no other organism on the planet can fit into that particular flower shape.

Narrator: Other insects, like bees, are less particular.

And when bees are drawn to a flower, its sticky pollen is drawn to them.

A static charge in a bee's hairs causes pollen to jump onto the bee's body.

Of the 20,000 species of bees in the world, perhaps the most well-known is the premier pollinator, Apis mellifera, the honey bee.

The honey bee is what's called a social bee, and lives in large colonies.

A single hive can pollinate up to 250 million flowers in a day.

This hive structure makes honey bees easy to domesticate in transportable colonies to pollinate some of our most important crops and to produce their signature product.

♪ [Speaking Italian] Narrator: A honey bee society is made up of a single queen, a few males, and thousands of female workers.

To make honey, the workers deploy an array of extraordinary capabilities.

They can tell time, navigate long distances, and communicate complex concepts to their sisters through a unique form of language using only their bodies.

Sylvana: Honey bees have a great form of communication.

So a worker finds a great pollinator garden with lots of nectar and flower resources.

That worker bee will fly back to the colony and do something called a waggle dance.

Gavin: Based on a certain orientation, it positions its body on a particular angle and then waggles.

The waggle is the quality of the food source, and the amount of time and distance that it moves is the distance that the food source is.

And then the angle by which the bee positions its body is the vector that the sisters need to follow to go find that food source.

Sylvana: A worker bee will drink the nectar from a flower, which is basically sugar and a lot of water, and they'll bring it back to the hive.

And the honey bees will then pass that sugary, watery nectar from bee to bee.

And as they pass it from worker to worker, they dehydrate the nectar, and so they concentrate it into a really thick, viscous liquid, and that's honey.

It's just super concentrated nectar.

Narrator: The stored honey feeds the bees year-round and supports the colony through the winter months, when no flowers are blooming.

The texture and flavor depend on the flowers the bees are foraging, and one of the most prized varieties in the world is France's miel de lavande, "lavender honey."

♪ [Speaking Italian] Narrator: When it comes to the honey bee's output, honey is just a drop in the bucket.

No longer prized only for their sweet syrup, honey bees have now been harnessed as the pollinating work horses of Big Agriculture.

Gavin: I was driving on Interstate 80 in the United States, and I saw a truck, and it was full of honey bee colonies.

[Bees buzzing] That's when I learned about the industrialization of pollination.

Jessica: We have this fantasy that there's just plants that grow and bees go there to pollinate them, but a lot of agriculture relies on a volume of these domesticated bees that actually need to be purchased, rented, and shipped from one part of the country to the other.

Narrator: In the United States, honey bees now pollinate a whopping 80% of our food crops-- fruits, vegetables, nuts, a business worth more than $16 billion a year.

Jessica: Honey bees, let's say, from Alabama, are then trucked to California when the almond trees are in bloom, and then once those flowers are done being pollinated, those hives are then trucked to another farm to pollinate things like blueberries or cherries or avocados.

Narrator: Many of these crops are not native to North America.

They were brought from Europe along with honey bees hundreds of years ago.

But because honey bees live in large colonies and need to constantly forage for pollen, they provide a highly efficient workforce.

Commercial beekeepers divide and replicate transportable hives on a mass scale.

Every year, up to 2 million honey bee colonies follow the bloom one farm at a time, and our lifestyle has evolved to depend on them.

Sylvana: Without the honey bees that are pollinating all these crops, our food would be very, very expensive or very, very bland, because we wouldn't be able to grow enough to feed ourselves.

We've come on this reliance of honey bees to help feed us.

Gavin: There's a lot of risk in that, when you've industrialized another species like that at this scale.

Because if there is a collapse, then we don't really have alternatives.

Honey bees are an essential part of American food production, but now they are dying off at an alarming rate.

Nearly half of all colonies gone in the last year.

That is a sharp increase from years past.

Akito: Around 2006-2007, a lot of beekeepers started to discover that large portions of their colonies would simply disappear.

So the adult bees would leave the colonies and just vanish.

Reporter: Researchers are calling it Colony Collapse Disorder, and it's affecting billions of dollars' worth of crops.

Different reporter: There has been a nationwide research effort to find the mysterious cause of what's been called bee Colony Collapse Disorder, or CCD.

It has decimated honey bee colonies across the nation.

Sylvana: This massive decline in colonies during that winter was the first time we really saw insect declines in the headlines, and as a warning bell for something happening in our ecosystem that's impacting the insects that we really need.

Narrator: After a worldwide investigation, scientists determined there was no single cause of the collapse.

It appeared insecticides, mites, viruses, and stress from constant relocation all form a deadly combination.

Some governments responded by restricting industrial pesticides, and new antibiotic treatments and beekeeping practices have helped honey bees stabilize for now.

Jessica: I think Colony Collapse Disorder was a good wake-up, because even, if only for a moment, it made the average human think insects aren't fungible, they're not disposable, there's a chance that we could lose them, "And my food, my children's food will be affected."

And I think that was maybe a turning point to realize insects are animals, and maybe they do something behind the scenes that we've taken for granted.

[Bee buzzing] Narrator: The ability to mass produce new colonies means honey bees are unlikely to vanish anytime soon, but beekeepers still lose around 30% of their hives every year.

The threat of Colony Collapse Disorder still looms as a warning of a larger crisis, one that has no easy solution.

Akito: So honey bees went through this major scare of Colony Collapse Disorder, but the disappearance of bees was just the first step in this process of understanding what's happening to insects.

We also can't forget about the native bees.

They are critically important because they pollinate native plants.

And oftentimes native plants cannot be pollinated by honey bees.

Narrator: Native bees are wild bees that pollinate 80% of flowering plants around the world, and while honey bees make headlines, native bees have also been quietly disappearing.

[Buzzing] Ummat: We really pay attention to honey bees because they're so economically important to humans, but there are more than 20,000 other species of bees that are responsible for pollinating many native plants around the world.

And these are really important to maintain native ecosystems, and we're not really paying attention to those bees as much.

Narrator: Unlike honey bees, the majority of native bees nest alone in hollow trees or underground.

Sylvana: The majority of bees are actually solitary, and so it's just one female who provisions a nest for her young, provides pollen and nectar for them, closes off their nest, and doesn't see them anymore.

Narrator: The solitary lifestyle of native bees means they can't be mass produced in colonies like their honey-making cousins.

Saving native bees will require saving habitat... or even creating new ones.

♪ In the heart of Cincinnati, a narrow stretch of concrete was recently transformed into a green oasis.

Sylvana: Hey, Georgie!

Oh, my God.

Hey, what's up, man?

Narrator: Two years later, Sylvana Ross is working with a local organization, the Queen City Pollinator Project, to see if the newly wild strip of city is successfully drawing in insects.

The project recruits citizen scientists to help search for native pollinators.

Sylvana: Queen City Pollinator Project is a nonprofit.

Our goal was to help out our native pollinators and also make people more aware that everyone can contribute to helping save our pollinators that are declining.

We realize you don't have to be a fancy scientist with research experience to collect data on pollinators and contribute to the science that's helping preserve pollinators and biodiversity.

Sylvana: Hello, everybody.

Oh, my God.

I'm so excited.

Thank you so much for coming out today.

So you're gonna get a clipboard with a couple data sheets.

And then once you get to your square, we're looking for flowers that are blooming.

And so I like to say, if a pollinator can eat off of that flower, then we're going to count that as a blooming flower.

And then you can catch, like, a lot of insects that are on flowers.

It's really easy to catch them when they're eating.

I like to say you give them a little hug with the catch cup.

So you put one on one side, the lid on the other and give them a nice big hug.

OK, everybody feeling good?

All right!

Cool.

Let's do this.

Sylvana: We get all different types of people to come and count bugs.

Is that a carpenter bee?

It might be.

I think it's a carpenter bee.

Yeah, it's a carpenter bee.

Sylvana, voice-over: We got people who love insects, and have been entwined with nature throughout their whole lives, maybe have loved bugs their whole entire life and want to help contribute... Sylvana: A little, tiny bug on this one.

...and then we also get community members that live in that area that see a bunch of people with insect nets and their phones out and say, "Hey, what's going on?"

And you hand them an insect net and a little catch cup, and then now they've become a community scientist as well.

Is that a little moth?

We got three bees and a butterfly.

Three bees and a butter-- Look at our pollinators!

♪ Narrator: It turns out many of the insects attracted to the new park are native bees and the most recognizable for its plump body, the bumble bee.

Sylvana: Bumble bees are another type of social bee.

They're also really important to our ecosystems because they're native and have particular relationships with certain flowers and certain plants that they're able to pollinate on a great scale.

A bumble bee colony starts off with a queen bumble bee finding a location to start her colony.

[Bees buzzing] When the queen lays her egg, she makes a little round comb, and will put her eggs in those combs and close them off.

[Bees buzzing] The larvae take about a few weeks to go from egg to larva to pupa to adult.

♪ And then they'll use their mandibles to cut their way out of their little cell.

♪ Once they emerge, they're down to cleaning, and then they'll move on to becoming a forager and collecting pollen and nectar for their bumble bee hive.

♪ Narrator: The spring emergence of bumble bees coincides with the blooming of the flowers that feed them.

But with the warming planet, the ancient partnership that has allowed them to thrive has now put them in peril.

Sylvana: Because bumble bees have a mutualistic relationship with flowers, usually their timing is synced with when flowers are blooming.

But because of climate change, flowers are blooming a lot earlier in the year, and so when the bumble bees emerge, the flowers that they typically might visit might already be done blooming.

And so not only are the bumble bees losing out on a food resource, but now those flowers are losing out on finishing their reproductive cycle.

And so this mismatch of these two mutualistic partners is now falling apart because of climate change.

Narrator: Climate change isn't only threatening their food sources.

As temperatures rise, bees in mountainous areas move to higher altitudes to find cooler climates.

But there's a limit to how high the bees can go.

In the last few years, the American bumble bee population has plummeted by a staggering 90%.

The creation of new green spaces and planting flower-rich gardens provides habitat that can help give bumble bees and other native pollinators a fighting chance.

Sylvana: We really hope that the data we collect we can share with the city to show that green spaces like this that support native pollinators, with native plants, are supporting a whole ecosystem.

Having a diversity of native bees helps flowers become more diverse and have larger yields than just using honey bees.

Narrator: Around the world, the services pollinators provide are worth more than three trillion dollars.

But while bees get all the buzz, other insects, like butterflies, are also critical for pollination.

As essential links in the food web, they maintain the plant diversity the ecosystem needs to thrive.

And in Kenya's Arabuko Sokoke forest, butterflies and humans are so closely intertwined, their relationship sustains whole communities and the forest itself.

♪ Dino: Arabuko Sokoke is one of Kenya's most magnificent 420 square kilometers of coastal indigenous forest.

Over a third of Kenya's butterflies are found in this forest.

And butterflies have become a tool for the forest's conservation.

All around the forest for over 30 years, farmers and traditional communities have reared butterflies through the Kipepeo Project.

Kipepeo means butterfly in Kiswahili.

Butterflies are collected, the caterpillars are reared, and the pupae are sold to butterfly houses and museums and gardens around the world.

[Speaking Swahili] [Conversation in Swahili] [Speaking Swahili] Narrator: Once the butterflies are caught, they're released in an enclosure where they lay their eggs, setting off one of the most incredible life cycles in the natural world.

♪ Dino: The life cycle of a butterfly involves very distinct stages.

Female butterfly lays an egg, a single egg often, on a leaf of a plant that's very specific to that species.

All her hopes are going into that egg.

♪ Ummat: The caterpillar hatches from an egg, and it turns into a little tube.

[Chuckles] And most of its body is dedicated to its gut for digesting food.

And it's such an innovation because the larva is specialized for the thing it needs to do.

It needs to feed and grow.

Akito: The organism needs to consume as much as it can as fast as it can, because there's lots of predators out there that are also looking to eat caterpillars.

Dino: These are stages of growth within the caterpillar, shedding the skin and growing bigger.

♪ Eventually, it molts and forms a pupa.

♪ And now something truly remarkable happens... this entire insect that has all these systems-- a digestive system, an eating system, legs-- changes, and dissolves itself and reforms through metamorphosis, growing a digestive system, a reproductive system, growing legs and wings and eyes, and all this complexity, all this color.

And then, completely miraculously, the pupa splits open and out pops this adult butterfly.

♪ First looking completely monstrous and bedraggled, all crumpled up and yet, within a couple of minutes, from the abdomen, liquid is pumped into the wings.

These wings fold out.

And a few minutes later, in the sunshine, the butterfly takes flight.

♪ Narrator: Butterfly houses around the world showcase the beauty of these species, fostering a global appreciation and respect for butterflies.

And these creatures, beloved for their metamorphosis, have a transformative effect on the women who rear them.

[Conversations in Swahili] Number five.

Number five, huh?

[Continues in Swahili] [Speaking Swahili] Narrator: The project now employs over 800 families, and the butterflies give the community a reason to make sure their forest habitat stays intact.

Instead of cutting trees, they now conserve them.

[Speaking Swahili] Dino: Each of those pupae contributes directly back to the livelihood of a rural family here in Kenya around the forest, and provides an incentive to conserve this forest.

Narrator: The exported butterflies bring much-needed awareness to these embattled pollinators at a time when, in some parts of the world, up to 90% of butterflies have simply disappeared.

The scale of the crisis has recently become clear with one of the most extraordinary and closely watched insects on the planet, monarch butterflies.

♪ In the high-altitude forests of Michoacán, clouds of monarch butterflies find a winter retreat in the region's rare fir trees called oyamel.

Most individual monarchs only live for about six weeks.

But when spring arrives, they set off on a journey that takes four lifetimes.

Ummat: I really like the idea of the generation starship.

This is a science-fiction idea, where a ship takes people on a journey to a distant planet, but the journey takes so long, it takes multiple generations to get there.

And this really exists in the world of insects.

Monarch butterflies do this massive migration, and take three generations to get from Mexico to Eastern Canada.

And then on the final generation, they fly all the way back down to Mexico.

Narrator: Monarchs use air currents to fly up to 150 miles a day.

They'll stop to lay their eggs on milkweed, the only host plant their caterpillars can eat.

Once the next generation emerges, the young monarchs continue the journey north.

After spending the summer in Canada, the last generation lives a full eight months longer than its ancestors, and makes the return flight all the way to Mexico.

Sylvana: How does an organism that's less than a gram and less than four inches make it 2,000 miles in a couple of months to then arrive in a place that they've never been before?

In fact, that their parents have never been before, their great-grandparents have never been before.

Gavin: The fact that it makes this journey across generations every single year is one of the coolest animal stories on the planet.

Akito: We're trying to figure out, as entomologists, why and how they actually do that.

And there's still a lot of mysteries in this process.

Narrator: Scientists speculate that an internal clock, the position of the sun, and genetic hard wiring all help with navigation, but no one knows exactly how the monarchs find their way back to the site of their only overwintering trees in Mexico.

Homero: Esa cultura es la que decía que La Mariposa Monarca es el alma de los muertos que venian a visitar los vivos, entonces eso se fue pasando de generación a generación.

Y afortunadamente, esto coincide, porque La Mariposa Monarca empieza a llegar el primero, el 2 de Noviembre, que es en las fechas que nosotros estamos celebrando a nuestros difuntos.

[Man singing in Spanish, indistinct] ♪ Homero: Yo, en mi caso particular, El Dia de Muertos, pues yo honro la memoria de mi padre.

♪ Homero: Desde que el se fue a la Universidad, el se enfocó en proteger los bosques y en La Mariposa Monarca mas que nada, porque, pues, el siempre decia, si temenos mariposas monarcas, pues viene el turismo.

De alguna manera, la gente de la comunidad tiene una fuente mas de ingresos.

Los bosques que hoy en dia aqui nos rodean son importantes, porque gracias a ellos, La Mariposa Monarca visita año con año.

Narrator: Monarchs have been making this spectacular migration for as many as 10,000 years, but this ancient cycle appears on the verge of being broken, as fewer and fewer return home each year.

Ummat: One of the things that's been especially conspicuous is the decrease in the numbers of migrating monarchs.

Jessica: In the last several years, the numbers have been terrifying low.

You know, down to a few thousand individuals in some of the counts.

Narrator: Deforestation, climate change, and loss of milkweed have had catastrophic effects on this natural spectacle.

In recent years, the number of returning monarchs has plummeted by up to 60%.

It may be that these highly adaptable creatures are running out of time.

Throughout history, when new threats arose, insects evolved new behaviors to survive, and bodies honed over millions of years.

If there's one insect that shows how clever these hardy survivors can be, it's the butterfly's nocturnal cousin, moths.

Akito: When I was younger, I thought butterflies were really cool.

Like, I thought, "Wow, I like these swallowtail butterflies.

They're big, and they're gorgeous, flashy."

So now I study moths more, and I've actually come to find moths quite cute.

I've come to really like them a lot, just because they're kind of-- I don't know if adorable is the right word-- but they're really-- they're really wonderful.

[Laughs] Something that a lot of people don't know about moths is that they're important pollinators.

We know that there's lots of plants with flowers that bloom only during the nighttime.

And the major pollinator for most of those flowers is moths.

Narrator: They may be the forgotten pollinators, but when it comes to adaptation, moths are masters of survival.

For 240 million years, they ruled the night skies.

Then a new predator took to the wing-- bats.

[Bat screeching] This deadly aerial threat triggered an evolutionary arms race and an explosion in moth defenses.

Jesse: Bats use echolocation.

They scream out into the night and listen for the returning echoes, which shows them where big things are, like trees and cliffs, but also tiny insects that they hunt.

Akito: So we think that when bats came on the planet, moths have had to undergo so many different kinds of evolutionary changes to be able to survive against their predators.

Narrator: The appearance of bats pushed moths to evolve a whole arsenal of defense tactics-- hairy bodies to absorb sound, long tails to distract them, and the ability to hear and produce ultrasound.

Akito: This ability allows them to defend themselves in different kinds of ways.

Jesse: When moths hear bats coming, they can spiral, loop, and dive to get away.

[Bat screeches] But many do more than just use their motor behaviors to get away.

They answer with their own ultrasonic reply.

[Moth clicking] They can communicate and tell the bats that they're toxic, chemically defended.

[Moth clicking] [Bat screeches] Others have the ability to jam the sonar.

In other words, they're able to create a sound that's so loud that the bat can't actually find the moth in the night sky.

[Bat screeching] We don't know anything about this process, because everything is happening at night in this dark sky, but we have now the equipment to try to unravel this whole system.

♪ Sumaco, Ecuador, is a lowland mountain in the Amazonian rainforest in the Andes, and we're going there because there's a really high diversity of moths.

So we think that moths have been on the planet for more than 300 million years.

What's interesting is that bats have only been on the planet for, we think, about 60 million years.

So within the last 60 million years, these moths have had to evolve to survive, and it's allowed this incredible diversification of moths.

Akito: Most of these moths we haven't seen before.

Jesse: A lot of hawk moths, lot of Adhemarius, Xylophanes.

A lot of tiger moths, too.

Jesse, voice-over: The primary question we're driving at is what drives diversity of species on the planet.

And bats are the second most diverse group of mammals.

Moths and butterflies are one of the most diverse groups of insects.

Understanding their interactions, their battles in the night sky, is unlocking many of the drivers of this diversity.

This is a beautiful moth.

Both of these guys should reflex bleed.

Akito: Smells bad?

Did you smell it?

Yeah.

Oh, yeah, very strong smell.

Akito, voice-over: We are looking for particular moths.

Here's one that definitely makes sound which we know about, Bertholdia.

Oh, yeah.

It's a very loud moth.

The ones that we're interested in are the ones that we know produce ultrasound.

We're also trying to understand other species that might be producing sounds.

A lot of the moths have never been tested, so our goal is to understand what kinds of species are doing it, how they're doing it.

Akito: Yeah, look at this.

It's already damaged by a bat.

It's amazing.

Look how the windows on the wings, they're clear.

You can see through them.

Beautiful.

Being in Ecuador is amazing.

This makes me super happy.

I just love seeing this extraordinary diversity, and knowing that there are places on the planet which still harbor so many different kinds of insects.

♪ OK, we're doing Melese.

Jesse: OK. Rolling.

Jesse, voice-over: Part of what we do is play back recorded bat echolocation attack sequences to moths.

And we try to see if the moths respond.

[Moth clicks] Jesse: There it is.

[Moth clicks] That looks great, and it's making great sound.

[Moth clicks] Akito: That was 12, right?

That was number 12?

Jesse: File 40, sound 44, moth 12-- Sorry, sorry.

Moth number.

Yeah, correct.

Correct.

OK. Akito, voice-over: One of the things that we're trying to do is to discover how they actually produce the sounds, because we don't actually know that very well.

[Moth clicking] So through microscopes, we can look for the particular structures.

Jesse: She's using her chest, her thorax.

Well, kind of the back segment, actually.

One way to imagine it is to think of like pushing in the side of a pop can that pops in and then sort of passively pops back out.

And that's the way this works, too.

It requires muscles to pull in, and then it passively pops back out.

Akito, voice-over: We've discovered that some species will produce sounds by rubbing their genitals together, and this produces ultrasound.

[Moth clicking] And they shoot that sound at the bats while they're flying.

Others will rub different parts of their bodies.

They have clicking devices that produce sounds.

All these are important in terms of talking to the bats in the night sky.

Jesse, voice-over: I think of them as tiny, little monsters because of their uniqueness.

There's so much diversity, and you see incredible features doing some function that's helping that animal survive.

And that's just the anti-bat side.

They have really long tongues, and they're learning an entire landscape of different flowers to nectar from, they're incredibly important pollinators, and they underpin all ecosystems on land.

And that's why their ongoing declines are so critical to understand.

Because if we lose insects, we lose everything.

Narrator: For all their ingenuity, fast-adapting moths may be confronting new threats even they can't outwit.

Rising temperatures and habitat loss have reduced many moth populations by nearly 50%.

But their night battles with bats are a testament to the age-old will of insects to adapt and survive.

And while some bugs have devised clever ways to avoid predation, others have evolved to become better predators themselves.

♪ ♪ "Bugs That Rule the World" is available with PBS Passport and on Amazon Prime Video ♪