All language subtitles for Swarm Natures Incredible Invasions When Worlds Collide BBC 720p HDTV_Subtitles01.ENG

The bees' lives depend on teamwork.

Animals can sometimes reach such
numbers they defy our understanding.

They seem to rise up
and invade our lives.

They become super swarms,

so immense
they're impossible to ignore.

From the outside,
they can be the stuff of nightmares.

From the inside,
they're a thing of beauty.

As we enter the heart of the swarm,

we'll discover what happens
when they meet our world.

It's 1995 at a football match
between Costa Rica and Italy.

Killer bees stage a pitch
invasion of a different kind.

The players' panic
is understandable.

These bees have been known to kill.

To understand what the swarm was
thinking, we recreated the encounter

and slowed it down to match
the bees' reaction times.

In Costa Rica, pitch invasions by
killer bees are surprisingly common.

Swarms like to make a beeline
across open areas,

which can bring them
right into the field of play.

By showing the action
in slow motion,

it becomes clear
that the footballers

are making the situation worse.

Swiping at the bees is
a complete waste of time.

Their reactions are so fast, they
can easily swerve out of the way.

It's also a very bad idea.

Movement not only makes them
angrier,

it gives them a target
to aim for.

The bees' lives depend on teamwork.

Retaliation is swift
and devastating.

Although each bee can sting
only once,

the sting left behind pumps out
a pheromone,

that whips nearby bees
into a fighting frenzy.

They join the attack and each new
sting brings in more angry bees.

Unlike honey bees, killer
bees rarely give up a fight.

But this swarm has other
things on its mind.

It's house-hunting.

Swarms arise
when a hive gets too big.

They view the camera
as a possible new home.

Bees are sensitive
to electrical fields.

That seems to make
the camera even more desirable.

A killer bee sting is no worse
than that of a honey bee,

but hundreds will sting
at any one time

and it's this behaviour
that makes them dangerous.

Lying down is
a surprisingly good idea.

The players merge with the ground

and the bees simply fly over them,
unable to find a target.

SIRENS WAIL

Killer bees were accidentally
created in Brazil in 1957

by crossing honey bees
with aggressive African bees.

Since then, they've spread
northwards

as far as
the southern states of America.

But there is a swarm that has
created far more devastation

than any killer bees.

Morocco, December 2004.

One of the oldest swarms
on the planet is on the move.

One of the ten plagues of Egypt,
they still invade one fifth

of the world's land surface

and affect one tenth of the human
population.

Even today,
meeting a swarm is unnerving

as this home video footage shows.

Eurgh!

That's crazy. They're grasshoppers.

Why just now?

Mommy! This is crazy.

Oh, my God, there are going
to be millions of these
and they're all flying off.

There's so many of them
just swarming over here.

They're still just coming, across
the road on both sides of the car.

Oh, my God! ..Complete
infestation...

Argh! Mommy! Mommy!

Swarm locusts start life
as hoppers,

the offspring of a solitary locust,

forced together by a shortage of
food.

The hoppers crowd together
to create an insect army.

It's an army that
marches on its stomach,
eating everything in its path.

When they run out of food,
they march some more,

crossing open ground
in vast battalions,

travelling up to 1.5 miles each day.

They stay as a ground
army for four weeks,

before changing into an air force.

Now, they really chew up the miles.
An average swarm contains billions

of locusts and the biggest outbreaks
can infest half a continent.

They're almost impossible
to control.

Seen for the first time from inside
the swarm, it's easy to see why.

As they fly,
they synchronise their wing beats.

This reduces turbulence,
making their flying more efficient.

Like fighter pilots,
they fly in perfect formation.

But here, one billion locusts

are covering an area the size of
Heathrow.

It would be an air traffic
controller's nightmare,

but the locusts maintain formation

by keeping a set distance
from each other.

They even have anti-crash detectors,
to avoid mid-air collisions.

They react six times faster
than a human pilot,

so even in such crowded air space,

split-second manoeuvres
can get them out of trouble.

Such state of the art flight
systems make locusts
a force to be reckoned with.

When they reach the human world,

they're almost impossible
to control.

They eat their own weight in food
in a day.

A large swarm can get through
200,000 tonnes, enough to feed
half a billion people.

Locusts aren't the only ancient
swarm that still plagues us today.

The house mouse originated in Asia
and spread with human agriculture.

When conditions are right,
they can quickly become plagues.

In South Australia,

mice outbreaks happen
on average once every ten years.

They erupt after a period of wet
weather creates bumper harvests.

By the time they're discovered,
it's usually too late.

It's every farmer's
living nightmare.

One unfortunate farmer filmed the
actual moment she realised her pest
problem was out of control.

Oh! They're in my boots! Eugh!

Concerned for
the safety of her pigs,

she throws caution to the wind.

Yuk! Oh!

SHE SCREAMS

Among the pens, the mice found
a limitless supply of food
and safety from predators.

It didn't take long for their
numbers to go through the roof.

The secret of their success is
a rampant sex life

that turns breeding into a weapon.

A pair of mice
can have babies every three weeks.

These, in turn, can breed just five
weeks later and their offspring,
five weeks after that.

Unchecked,
the numbers just keep growing.

In theory, one mouse
and her offspring

can produce 3,000 mice a year.

With few predators to control them,
theory rapidly comes fact.

In one outbreak, 35 million mice
were killed in just one month.

Even this hardly dented
their numbers.

Eventually, stress and
disease take their toll
and the population crashes.

For every 1,000 mice,
just two will remain.

But they're breeding machines,

ready to surprise us
at any time in the future.

Some swarms are more predictable.

This eerie invasion
happens like clockwork

once a year
in the Midwest of America.

It can be so dense,
it slows traffic to a crawl.

The swarms can smother an area of
4,500 square miles

and even show up on radar.

These are mayflies.

They have emerged
from the Mississippi River,

where they lived as larvae
for the past year.

They will exist as adults
for only a day.

Their cue is a water temperature
of exactly 17.5 degrees centigrade.

They hardly have a chance to
try out their new body and wings

before it's all change again.

For some unknown reason,
the body splits

and an almost
identical mayfly emerges.

The previous form may have
existed for less than an hour.

They soon spread their second set of
wings, this time in a mating flight.

By emerging together,
there's safety in numbers.

Nothing could eat this many.

They soon return to the Mississippi
to lay their eggs.

Each female lays up to 8,000, making
up for the billions of mayflies

that never make it back
to the river.

It's easy to get lost. They navigate
using the moon as a reference point.

But near towns,

this ancient navigational system
is next to useless.

Artificial moons are everywhere
and these beckoning lights cause

mayflies to become
hopelessly confused.

The road also reflects light
like the river,

attracting the mayflies
down to lay their eggs.

As the mayflies are lured
further into town, they spread
their own haze of confusion.

This gas station is being attacked
by something.

I don't know what
those bugs could possibly be.

And that lady won't
even get out of her car.

That is really creepy.

But not everyone's so mystified.

The locals have seen it all before.

It's mayflies' breeding day...

in South Ballston Virginia.

I don't know if you can see this,
but this is mayflies, and they
come out in the gajillions!

And these things,
they come out like this

on certain days, all at once

and they cover the streets
of downtown South Ballston,

and probably just about anywhere
where the damn river runs through.

It sounds like the wind
is blowing out here,
because there's so many of them.

It's just amazing,
you just wouldn't believe it.

There are certainly huge numbers,

an estimated 18 trillion emerge
for one night only.

3,000 times
the world's human population.

Many fly straight to
the bright lights of the city,

10,000 may cover a single neon sign.

By extraordinary coincidence,
the invasion often coincides

with one of America's most
important celebrations -

Independence Day.

As crowds fill the streets
of La Crosse, Wisconsin,

they are outnumbered by mayflies
25 million to one.

Stand too close to a light and
you certainly know it's mayfly day.

Fortunately, the mayflies
are totally harmless.

They have no mouth parts, so they
can't even feed, let alone bite.

To us, they seem out of control,

but inside the swarm,
it's a different picture.

These angelic forms
easily avoid each other,

even in the thickest gathering.

As America celebrates
its independence,

the mayflies enjoy
the last day of their life.

Bird swarms invade our cities too,
a fact which many find unnerving.

There's some of them. Oh, my God!

It's like The Birds, it's like
the invasion of The Birds over here.

Look at this!

We're driving through them.

I have never in my life
experienced this.

Let's get out.
I don't know, Daddy can get out.

The birds are everywhere.

Is this a phenomenon, or...?
Ooh, my gosh!

I'm very shocked at this.

I don't understand
what's going on here.

I think this is like something
that happens

before like a big earthquake
or something.

In recent years, huge flocks of
roosting birds have become a common

sight in many cities, but nowhere do
they reach the numbers seen in Rome.

Here, they have become a super
swarm that gets bigger year on year.

Ten million starlings flock together

to create the most astonishing
aerial display in nature.

These spectacular aerial displays
are seen

between October and February,

when birds pour into Rome
from all over northern Europe.

To create such perfect synchrony,

it was once thought that the birds
might use telepathic communication.

But in reality, the birds react
13 times faster than any person.

They turn in exact synchrony
with their nearest neighbours,

but the tiniest delay in their
reflexes help create these
mesmerising waves in the sky.

Until recently, the spectacle
could only be seen from the ground.

Now it's possible to take cameras
into the swarms and fly among them.

This aerial ballet acts as a beacon
to others still entering the city.

Smaller parties join the bigger
flocks, increasing their numbers.

As they swirl in the sky,
they collectively make decisions on
where they should spend the night.

After an hour of pirouetting,
the birds dive downwards,

having decided together
where they will roost.

Birds are drawn to cities
because they're warmer than
the surrounding countryside.

Rome, with its balmy
Mediterranean climate,

is an especially popular
destination.

But the city pays a heavy price
for hosting this incredible air
show.

Each night, ten million birds
produce

seven tons of excrement, playing
havoc with the paintwork of cars.

As the birds settle down
for the night,

there is a constant rain
falling below.

Slippery roads and pavements
cause accidents too,

it's a health and safety nightmare.

But the starlings don't
have it all their own way.

They may look like extras
from a sci-fi B-movie,

but these people really are
wearing their work clothes.

They are starling busters,
hired to clear the streets
of this urban menace.

Their weapon of choice
is a loudspeaker.

BIRDS SCREECHING

It plays back a starling's
alarm call, amplified 100 times.

For these birds,
there is simply nothing scarier.

This roost of 100,000 starlings
will have to up sticks and
find somewhere else to roost.

This bizarre experiment has been
running for the last 12 years.

It certainly moves the starlings,

but Rome offers plenty of
alternative accommodation

and the number of winter visitors
keeps rising.

Some swarms only invade
our cities once in a generation.

It's July 2008,
and in the suburbs of Cincinnati,

an alien invasion is about to begin.

These periodic cicadas have lived
deep underground

for the last 17 years, but now,
under the cover of darkness,

they start to emerge.

Across vast areas of the state
of Ohio,

ten billion cicadas
join the alien invasion.

They have spent their subterranean
lives sucking the sap

from the roots of trees.

Now, in the 17th year,
when the ground warms

to 18 degrees centigrade,
they all come to the surface.

They make their way
towards the nearest tree
and immediately start to climb.

Their marching orders are
genetically programmed

and so is their sense of timing.

But genetics couldn't predict
the changes made by those
living in the world above.

These cicadas are the lucky ones.

Each year, more of the surface
becomes concreted over,
leaving millions trapped beneath.

It's Memorial Day.

In the 17 years the cicadas
have spent underground,

America has fought three wars
and had three Presidents.

And the human world
has been transformed.

With people absorbed
in the commemorations,

the cicadas go mostly unnoticed.

But all this is about to change.

The cicada nymphs break out
of their old body,

a miracle that can
take as little as ten minutes.

Soon, all the cicadas undergo the
same extraordinary transformation.

But before these crumpled wings
can fly,

they must be pumped full of blood,
a marvel of insect hydraulics.

Their gossamer wings
need time to harden.

While they wait,
they're often noticed by their
human neighbours for the first time.

See that tree right there?

It has lots and lots
of cicadas on it.

There's, like, a bunch of cicadas
on the floor too.

So I don't exactly
wanna, like, step on any of them.

Tons of them, like, tons.

On her flowers. Cicadas everywhere.

Cicada mania.

While some enjoy the novelty,
others are driven crazy by the
noise.

I am putting myself out
here in the middle of this
disgusting invasion of insects.

It's like I'm a journalist
in a war-zone.

I can hear these things inside,
with air-conditioning on high

and Metallica blasting.
I kid you not.

The combined racket
reaches 100 decibels, far louder
than a jet flying overhead.

The male makes the sound by
vibrating a drum-like organ
hidden in his body.

It's not a good time
for those with sensitive hearing.

Adults have seen and heard
it all before, but for kids
it's a totally new experience.

One they won't see again
for 17 years.

By appearing all together,
cicadas swamp predators
with too much food to eat,

but their trick of using such
an odd intervals of years
is a masterstroke.

It stops any predator
breeding to exploit the feast.

They count their 17 years below
ground by measuring seasonal changes
in the pressure of tree sap.

Although millions are eaten,
the majority manage
to find each other and mate.

After mating, they use
their egg-laying tube as a saw

to cut a slit under the bark,
laying 30 eggs in each incision.

Job done,
they drop dead in their millions.

Having spent the span of
a human childhood underground,

their adult life
is over in just three weeks.

Cincinnati is left
with a huge clean-up operation.

Hundreds of tons of
dead and dying carcasses

from this single emergence alone.

17 years is the longest
cycle of any breeding swarm.

Most occur once every year.

These Cuban land crabs have
spent the last 11 months

hidden in the rainforest.

Today, they begin a six-mile march
back to the sea.

Crossing open ground is dangerous.

They can soon become cooked
in the sun, but civilisation
soon stops them in their tracks.

For the crabs,
this is a shady paradise.

Cool air flowing through
the shutters makes thousands cluster
together to avoid drying out.

But it can only be a temporary
pit stop, as the urge to march
soon drives them on.

The crustacean army is 100 million
strong

and their cue to migrate
is triggered by the spring rains.

The hordes have to cross
a coast road

that forms a barrier
between land and sea.

It's hardly a motorway, but for the
crabs it's an accident black spot.

For unsuspecting drivers,
coming across the invasion

is a memorable experience,
making some reach for the camera.

Traffic comes to a standstill,
as cars try to find a way through.

TOOTING

Those that ignore
the crabs usually pay the price.

One garage mends
100 punctures a day.

Despite the carnage, the crabs
are distinctly unsentimental.

Seizing the chance
for a roadside snack.

Fortunately for the crabs'
ultimate survival,

most of the millions make it
to the other side,

then it's an easy sprint to the sea.

Land crabs came from the ocean.

They need to return here
to lay the eggs

that will secure the next
generation.

Crabs only swarm in the breeding
season, but some animals
live their entire life as a swarm.

It's May 2008
and the rains have arrived

in the mountains of East Africa.

One of the most organised swarms
on Earth has appeared above ground.

They're driver ants, an insect
with a fearsome reputation.

In the rainy season they form
these extraordinary hunting trails.

Large soldier ants line the trail,

protecting the smaller workers
inside.

Their massive jaws create
an impregnable barricade.

The soldiers create
these protective tunnels
whenever they cross open ground.

The trails radiate
from the nest in every direction,

some stretch 100 metres.

A worker running at full pelt
takes 45 minutes to run its length.

The soldiers protect the trail
at any cost.

Although blind, they're highly
sensitive

to vibrations and air currents

and become instantly
defensive when under attack.

Stress pheromones put
the whole task force on alert.

They're ready to take on anything,
including people.

They're programmed to keep
the trail moving or die trying.

Driver ants are the stuff of legend.

It is said that they kill
everything that crosses their path.

It is said that no animal is
safe when they're on the warpath.

It is even said that they'll enter
huts to attack people

or kill babies left unattended
in their cots.

BABY CRIES

The truth is somewhat different.

Although the bites are
painful, against people
they're purely defensive.

The jaws may slice through
human flesh like butter,
but it's simply a warning.

Despite the myths, driver ants are
still ruthless killers,

but in a way that often benefits
the villagers.

Dangerous pests like scorpions are
quickly set upon by the ants.

Even the scorpion's deadly sting
is powerless

against this invincible army.

Both workers and soldiers join
the attack, dividing up their
roles according to their size.

As some look for a chink in its
leg armour, others prise open
its body plates like a tin opener.

With its sting immobilised and
faced by such overwhelming odds,

the scorpion eventually
gives up the fight.

The dismembered body is hauled back
down the trail to feed the nest.

The farmers' fields provide
even more opportunities
for the attack force.

Pests disturbed by digging
are soon dispatched by
hundreds of razor-sharp jaws.

The ants make a clean sweep,

capturing up to 100,000 insects
in a single raid.

Despite the ants' formidable
reputation,

most farmers value
their role as pest controllers.

Their feelings about another African
swarm are equally surprising.

Once a month throughout
the rainy season,

mysterious clouds rise over Lake
Victoria, Africa's largest lake.

This smoke on the water
is not quite what it seems.

It's actually a living entity

comprised of trillions
of individuals.

They're lake flies, a kind of midge
that emerges from the water

in astronomical numbers
at the time of the new moon.

There have always been flies here,

but increased pollution
from fertilisers and sewage,

while damaging the lake,

is encouraging these huge columns
of flies.

In terms of sheer numbers, these
are now the biggest swarms on earth.

Eventually they make landfall

and people encounter
the flies for the first time.

On land, countless numbers swirl
around every physical feature

as they shimmy in courtship flights.

Although the air is choked
with billions of flies,

daily life continues.

It's rumoured that the flies can
suffocate people by sheer number.

In reality the lake villagers
are surprisingly blase

about this living smog.

Eventually the flies take a rest,
covering every available surface

as they break off
from their mating rituals.

Like many swarms, the midges emerge
together to swamp predators

with too much food to eat
at any one time.

Birds even migrate to the lake

to make the most of this monthly
free lunch.

But it's not only birds

that can't bear to see so much
protein go to waste.

Such incredible quantity of biomass
is equivalent to huge herds of game,

but far easier to catch.

A frying pan
makes the perfect weapon.

The flies are so valuable
the whole village joins in the hunt.

The saucepans have been dampened
first to make the flies stick
and then clump together.

These midges are so nutritious,

they're valued as a supplement
to the local diet.

Each patty contains
half a million flies

and has seven times more
protein than the average beefburger.

For people who have little protein
in their diet,

this burger bar
is a health food centre.

Each village has its own recipes,

but fly burgers always
go like hot cakes.

In times of famine, this traditional
method of dealing with the monthly
invasion becomes ever more relevant.

Both ants and flies are
swarms with a positive side,

but one African plague
has no such redeeming features.

It can be
heard long before it arrives.

These are the most numerous birds
on Earth with a growing population

that may now be more
than ten billion.

The largest flock on record
consisted of over 40 million birds

and took five hours to pass.

Sometimes known as the locust bird,

these are quelea, a type of weaver.

They follow the seasonal rains
in an endless search for food.

Water holes draw
huge numbers together.

They need to drink twice a day

and usually stay no more than
ten miles from the nearest water.

Being sociable allows them
to share information.

Each bird acts as a scout
and those that have found
food let their neighbours know.

This guarantees that the departing
flocks set off in the most
promising direction.

They eat grass seeds but,
unfortunately for African farmers,

they prefer the more succulent
domesticated varieties,

getting through 10,000 tonnes a day.

Smaller parties break off
from the main flock to make sneaky
raids on the farmers' fields.

Even a relatively small flock
will demolish

an acre of rice in less
than an hour.

SCREAMING

Subsistence farmers suffer the most.

It's a full-time occupation
keeping the crop raiders at bay.

HE SHOUTS

It's like trying to dam
an ever-flowing river.

As the flocks separate and reform,

predicting where they might land
is anyone's guess.

With their livelihood at stake,

the whole village creates
a taskforce

to try to stop them settling.

HE BANGS DRUM AND SHOUTS

A flock of one million quelea
consume 60 tonnes of food a day

but, as they're always on the move,

they're almost impossible
to control.

Only when the birds roost
do the farmers get some respite.

Eventually the birds have
to stop their endless travelling.

Nesting is their most vulnerable
time.

The red-billed males
do the main work,

weaving up to 20 of these intricate,

bowl-shaped nests to attract
different females.

He takes the greatest of care, as
his quality of work is being judged.

Only the finest weaving
passes the test.

If she approves, she moves inside.

But stopping to breed
has made them vulnerable.

A colony may cover four square miles
and hold 300,000 birds,

all breeding
a new generation of crop raiders.

As sunset draws the birds back
to the nest,

they pay the ultimate
price for feeding off our success.

COUNTDOWN IS SHOUTED

In the birds' world,
this is Armageddon.

Over 100,000 annihilated
in a single blast.

The inferno brings temporary relief
to nearby farmers but does nothing

to stop the ever-expanding growth
of Africa's quelea population.

We may unintentionally
encourage swarms

but we cannot control them.

It's August 2008.

In the Mississippi and its many
tributaries,

a purely man-made swarm
is on the rise.

In the 1970s,
silver carp were accidentally

introduced into these waters
after escaping from a fish farm.

They now outnumber local fish
by 10-1.

They have some truly
bizarre behaviour.

Some can clear
three metres in a single leap.

They say when fish are leaping,
it's good for anglers.

It's certainly the case
in this part of the river.

Here, fishermen don't
even need a rod and line.

Fish are only too willing
to do the job for them.

It's a phenomenon
that takes some getting used to.

Whoa!

I got him too! There's a guy.

Look out!
SQUEALING

Hey!
LAUGHTER

That could be cut bait.

That could be cut bait.

Hey! We don't even have to get
the fishing pole wet! Look out!

Damn it, let's eat that
thing, see what it tastes like!

But this kind of angling
has its dangers.

Oh! No!

Right in the mummy-daddy button!

It's not just anglers
who are affected.

Pleasure craft
have to run the gauntlet too.

Did you see that?

That would hurt!

My goodness! Holy toledo!

There's massive fish flying

out of the water behind them.
I mean, large.

That's insane!

Get us out of here!

The secret of this extraordinary
behaviour lies in the boats' motors.

The fish mistake pressure waves
from the propeller

for the movement of predators

and literally jump with fright.

They react in alarm
to every passing boat.

With numbers close to
bursting point,

each leaping fish scares
its neighbour,

creating a dangerous chain reaction.

As some weigh over 40 pounds,
collisions can be deadly.

In some parts of the river, 200 fish
missiles can launch at any one time.

They've already caused
serious injuries and,

as they spread to other rivers,
the danger increases by the day.

Silver carp are a swarm
that we accidentally created,

living proof that, as we interfere
with the balance of nature,

we create more swarms.

But there is one swarm that we have
been deliberately encouraging

for thousands of years.

The honey bee is the only swarm
we have ever domesticated,

but we're still unravelling
the mysteries

of much of their behaviour.

For those who understand
the swarm's inner mind,

it's possible to control them in
a way that is quite extraordinary.

The bees are being summoned
by a secret signal,

one that causes
them to act with a single mind.

Swarms are made
from thousands of organisms

but they work by acting as one.

By understanding the swarm's
secret language,

it's possible to make them
do the most extraordinary things.

100,000 bees cover his body,
creating a living suit.

He has such control over the bees
he rarely suffers a single sting.

He is a professor of entomology,

and has been studying bees and
their communication all his life.

By covering his body with
the pheromone that the queen bee

uses to control her hive,
he has them at his command.

They react by protecting
him with their bodies.

To them, he is the queen bee.

Using science, he has learnt
to control what most of us dread,

and the result is quite disturbing.

As he brings a swarm into our world,

people are forced
to confront their fears.

They also see that, with knowledge,

such an incredible force
of nature can be controlled.

When swarms invade,
we are inevitably separated

by an invisible barrier created

by our different senses
and perceptions.

Swarms may share our world but the
gulf between us couldn't be greater.

To control the swarm, we need to
understand how they see the world.

But swarms not only experience
things differently from us,

they think in a different way too.

The next programme will explore
the extraordinary alien intelligence

that controls the swarm.

Subtitles by Red Bee Media Ltd

E-mail subtitling@bbc.co.uk