All language subtitles for BBC.Life.In.The.Undergrowth.2005.Part2.DualAudio.DVDRip.XviD-EaGlE

A Summer evening on the Korus river
in central Europe.

Its waters are mirror- smooth -
but on this particular day of the year,

all that is about to change.

Giant mayflies - Europe's largest -

are starting to rise to the surface
and struggle out of

the skins in
which they lived as larvae.

At first they come in ones and twos.

Soon there will be millions.

For two years, they've lived underwater.

Now they must fly - to find a mate.

This should be the climax
of their lives.

The first to appear are quickly taken
by predators.

But soon the swarms are so huge

that neither fish nor birds can
make any impact on them.

The first mayflies to emerge
in this mass hatching

on this river in Hungary are all males.

As soon as they free themselves
from the larval skin on the surface,

they take off and seek safety
in the banks

and there they hang on trees
and bushes -

or indeed on my finger and the reason
they have to rest like this is

because they still have
to make one final molt.

Their wings that were transparent now
have a handsome blue tinge;

and the elegant filaments
at the end of

their abdomens are even longer
than before.

They're looking for mates -
but they have a problem.

They can't feed
for they have neither mouth nor stomach.

They have to fuel their flight entirely

from the reserves of fat
that they built up

when they were larvae feeding
in the river.

But that fat will only last them for
about half an hour of flight time.

So the race to mate now
becomes a frantic one.

The females begin to rise
to the surface

and the males fly up and down
the river searching for them.

As soon as they find one,
they all pounce on her,

competing to be the one to
fertilize her eggs.

But the struggle of doing
so saps their limited energy.

Before long they begin
to run out of fuel

and though they flutter despairingly,

they can't maintain themselves
in the air.

Win or lose,
their lives are almost over

and dead bodies start to litter
the surface of the water.

But the females are still in the air.

They're flying up-stream,

judging the depth of the river
and the currents in it,

to find a place
where they can lay their eggs

so that they will float back down-river
to the same sort of place

where the adults themselves lived
as larvae.

The ancestral mayflies were among
the first creatures

of any kind to take to the air
about three hundred

and twenty million years ago.

For them,
as for their living descendants,

flight was a brief but invaluable way
of finding a mate

and expanding
their breeding territories.

The river has also been the home
of another kind of insect

with an equally ancient ancestry

and it too is beginning to emerge
from the water.

Bigger and more ferocious
than the mayfly larvae,

it has been feeding on tadpoles
and even small fish.

But that phase of its life is over.

Now each one has to haul itself
out of the water

and into the air.

On the top of its thorax it carries
a bulging back-pack.

It hunches itself
and its outer skin splits.

A very different creature begins
to appear.

White threads are drawn out of
its flanks.

They are the linings of thin tubes
that penetrate deep into its body -

air tubes that will enable
the insect to breathe,

now that it is out of water.

It gulps air - inflating its body,

forcing fluid into the bundle
on its back.

Its wings begin to unfurl.

Ten minutes later - the wings open.
They'll never close again.

Next, the huge muscles
within its thorax

must be exercised
to prepare them for action.

And it's away.

Dragonflies, like mayflies,

belong to the most ancient group
of insects

that flew over the land
and here in the Museum

in Harvard there are fossils of them
that are 150 million years old.

They're almost identical with species
that are still flying today.

However they are
by no means the oldest.

We know that there were other
dragonflies even earlier -

225 million years ago -

that were flying through
the Coal Measure swamps.

We don't have complete specimens
of any of those

but there are some tantalizing
and amazing fragments -

and here's one.

This marvelously preserved wing
has very much

the same pattern of veins supporting
panels of membrane as living species.

The thing that makes it
different is its size.

From base to tip it
measures twelve inches -

30 centimeters.

Little imagination is needed to replace
the membrane that must have been there.

This insect must have had a wing-span
as big as a seagull's.

Vibrating these wings,
preparing for flight,

must have been a formidable business.

A creature this size must have been
at least ten times heavier

than the largest insect flying today.

How did it manage to get into the air?

One suggestion is that
in those far-off times

there was much more oxygen in the air -

and that would have given
the extra power

needed to beat these huge wings.

But it's a fair guess that this ancient
pioneer of the skies flew

with much the same technique
as dragonflies do today.

Living dragonflies can reach speeds
of nearly 40 miles

an hour and fly several miles
in their search for new territory.

They're all aerial hunters,

relying on their supreme
aeronautical skills

to snatch their prey from the sky.

Their great agility in the air comes

from being able to beat each of
their two pairs

of wings quite independently.

You can see clearly that they do this,

when the camera slows down the action
four hundred times.

This one is coming in to its perch.

Perfect control is essential to make
all the tiny adjustments needed

for an accurate pin-point touch-down.

All dragonflies, when they perch,
hold their wings outstretched.

But they have close relations -
damselflies -

and they perch with their wings
closed above their backs.

Mosquitoes stand little chance
when damsels go hunting.

But flight for damsels,
as for dragonflies and mayflies,

is primarily the means to find a mate
and to breed -

and to do that they, like the others,
need water.

Flight is itself an important element
in their courtship.

These blue males must first establish
a territory

for themselves above open water -

and that involves aerial jousts
that can last for hours.

Mature females -

whose wings in this species
are not blue but golden brown -

are attracted to those males
who control good places for egg-laying.

But the males must nonetheless display
the correct wing signals.

This one, patrolling his territory,

is using a special flight
to flaunt his handsome wings,

inviting females to join him.

A female signals her willingness

to consider doing so with a flick
of her wings.

So now he treats her to his full display.

The female's tail-up posture
is apparently a signal

that declares that she's not yet
sufficiently impressed.

Now, it seems, he's got it right -
her tail is pointing downwards.

He grabs the back of her neck

with the claspers
at the end of his abdomen.

She brings her abdomen forward to reach

a chamber under his thorax
where he stores his sperm.

His first action, though,

is to scour out her genital
tract to remove any sperm

that might be there
from a previous mating.

Only when he's done that,
will he inject his own sperm.

And now he must show her the best places
in his territory for laying eggs.

He flies up and down,
with his tail curled

and lands on a suitable piece
of vegetation.

The female settles down to lay,

cutting slits in the plant stems
with her ovipositor

and inserting an egg into each one.

She may lay as many as thirty.

And all the time,

the male keeps guard lest rival males
should try to mate with her.

In other damsel species,

the males make sure that no other male
can reach their partners

by keeping hold of them
throughout the whole process.

The young that hatch from the eggs
of these insects -

the larvae -
look very unlike their parents.

This is a dragonfly larva -

and it's in this form that dragonflies
spend most of their lives.

The larvae of both dragonfly
and damselfly are savage predators.

They'll even feed on their own kind
if they get the chance.

This particular larva
has a very special problem.

It's a cascade damsel and it has
to snatch prey that is swept past it

by the rushing water.

Cascade damsels are very rare
and live around

just a few central American waterfalls,

like this one
in the mountains of Costa Rica.

The adult male has to perform

his courtship flight
under very difficult conditions indeed.

Somehow, he's able to fly even
when he's dripping wet

and he shows off to the females

by actually flying through
the cascades of water.

To be a good breeding territory,

the vertical rock surface
has to be covered

by just the right amount of water.

Too deep and prey may be
out of reach;

too shallow and the larvae
could be picked off by birds.

A female will only mate with a male

if she approves of his choice
of territory.

And this one, it seems, does.

This is it - and she carefully fixes
her eggs to the rocks.

But not all damsels need great areas
of open water for breeding.

In the rain forests of Central America,

like this one here in Costa Rica,

there's a damselfly that has managed
to break the link

with open expanses
of water like rivers and ponds.

It's also one of the most spectacular
members of the entire family.

The helicopter damselfly,

the largest in the world with
a wing-span of up to 20 centimeters.

The males tend
to frequent sunlit patches

where the females can see them easily

and they have a special lazy flapping
way of flying that is,

in itself, an invitation.

But although helicopter damsels can
live away from rivers and streams,

the females nonetheless require
a little water

in which to lay their eggs
and there is just enough

in this little hollow here -
and with luck she'll come down.

And into the water they go.

But these eggs have water-tight casings,

so they can be laid in air.

They are butterfly eggs.

The link with water has been broken.

Butterflies fly in a very different way
from dragonflies.

They overlap their two pairs of wings
so that they flap as a single pair.

They can't fly as fast
or as aerobatically

as dragonflies but they nonetheless
are tireless in their search

for the particular food
that will suit their young -

and in the case of the cabbage white -
that's cabbage.

Now on the surface of this cabbage leaf
there's a patch

of tiny little pill-box-shaped eggs.

And when they hatch,

the baby caterpillars will emerge
and make an instant meal of the greenery.

And they are already stirring.

But the first dish on the menu
is not vegetables.

It's the shells
of their own egg capsules -

protein-rich and far too nourishing
to be wasted.

That first course, however,
doesn't last long.

Now for the main dish -
cabbage leaves.

When cabbage plants are damaged,

their leaves release a smell
and that quite often attracts

the attention
of a rather different insect.

It's a tiny wasp called Cotesia.

She too is trying to make sure

that her young have food
immediately available -

but they like living flesh.

So she injects her eggs
into the butterfly's caterpillars.

She does this
with such surgical precision

that her victims
are not mortally injured

and they continue feeding as if nothing
had happened to them.

But now much of what the caterpillars

so laboriously gather
goes to nourish the wasp grubs

that are developing within them.

As the caterpillars grow,
they shed their skins.

They do so five times until ultimately

they are eight hundred times heavier

than they were
when they first hatched.

This fully-grown caterpillar
must now find shelter.

A strand of silk
of silk trails behind it -

silk with which it ties itself
to a twig.

And here, over a couple of days,
it changes into a chrysalis.

Those caterpillars that were injected

by the Cotesia wasp don't
get that chance.

The grubs within them are now emerging.

They too spin silk which hardens to

form a cocoon beneath
the caterpillar's empty skin.

Inside, the wasp grubs are
transforming themselves

and two weeks later -
out come the adult wasps.

A different future awaits
the chrysalis.

Within its shell
and over a similar two weeks,

the caterpillar's body has been
broken down and reassembled -

and now the adult is ready to emerge.

Its wings, like those of
a newly-emerged dragonfly,

need pumping up with liquid.

The creature that was once an egg,
then a caterpillar,

then a chrysalis has attained
its final incarnation.

So another generation
of cabbage whites set off

to find good places for their young.

With their fragile- looking wings
and apparently erratic flight,

butterflies might not seem
to be the most powerful of flyers,

but in fact
they are extremely accomplished aeronauts

and they can fly hundreds of miles

if necessary to find
the food they need.

Some butterflies use the power
of flight for another purpose -

to escape bad weather.

These lush sub-tropical valleys
in southern Taiwan are warm

and green all year round
and in winter,

they're filled by literally millions
of butterflies.

They've all come from the north
of this great island,

five hundred miles away,

for there the cold weather
has killed off the plants

on which they fed during the summer.

In the mornings they take off
from their roosts

and head for the forest canopy,

to warm themselves
in the rays of the rising sun.

They have to conserve
as much energy as they can,

so instead of using their stores
of fat to warm themselves,

they absorb the sun's heat.

There are four species
of crow butterflies here

as well as two species
of blue tiger butterflies -

and all find enough food
to sustain themselves

in these warm and fertile valleys.

Butterflies feed on liquid -

nectar and the juices
of rotting fruit -

and to suck it up they have,
instead of jaws,

an extraordinarily long
but extremely thin tube.

In a newly-emerged butterfly
this tube is in two pieces,

for it is in fact a highly modified
pair of mouthparts.

Each half has its own muscles
and nerve supply

so that the whole unit is fully
movable and controllable.

As the young butterfly prepares
for adult life,

these two sections
are zipped together to

form a tube like
a miniature drinking straw.

A special fluid cements
the two halves together.

The tube is largely made of
a material called resilin which,

when distorted,

springs back to its original shape -

in this case a spiral
like a watch spring.

When the muscles within it contract,

it straightens into a long probe
that the butterfly can

then insert deep into a flower.

Butterflies and moths have the largest
of all insect wings

and their great size means
that they can be used very effectively

as bill boards on which
to display patterns proclaiming

the species of their owner.

The patterns are produced
by tiny scales

that cover the wings
like tiles on a roof.

Some have a microscopic structure
that refracts

the light and gives the wing
a brilliant iridescent shimmer.

Others contain chemical pigments.

With these lovely advertisements,

a male butterfly displays to females
and warns off rivals.

Vivid patterns and bright colors

are used to a much lesser degree
by moths -

for many are only active
at night when colors,

of course, are not easily seen.

Moths also feed primarily
on nectar which they suck up

in the same way as butterflies do.

But one moth manages to tap a food
source no butterfly has yet exploited.

It comes from lantern bugs
which feed by drilling

into the bark of a tree

with their proboscis
and sucking out the sap.

This contains a little protein,
which the bug wants,

but a lot of sugar,
most of which it doesn't want.

So it squirts out the sweet excess

and to make sure that this doesn't
attract ants that might attack it,

it fires the droplets well away
from the tree trunk

with a tiny spring-
loaded spatula at the end of its abdomen.

One enterprising species

of moth regularly sits behind
the bug all night

with the curled tip of
its proboscis delicately placed

in the stream of droplets.

As sugar water accumulates,
so the moth sucks it up.

Most moths, however,

feed by the rather
more laborious method

of flying from flower to flower.

A few - the busiest -

do so not only at night
but during the day as well.

These are the hawk moths
and there are several species

of them gathering nectar

from this buddleia bush
in the south of France.

This hawk moth can fly very fast indeed
when it wants to but it can also hover,

as it's doing now, to sip nectar
from each one of these small flowers.

Beating its wings as fast as this,
of course, takes a great deal of energy,

so these hawk moths have
to spend much of their day going

from flower to flower sipping
the nectar which is so rich

in the carbohydrates
they need to power their flight.

They have huge forward-
pointing eyes that enable them

to aim their proboscis
with such accuracy

that it slips into the exact center
of each tiny flower.

With so many minute flowers
so closely bunched together,

it would be easy
for the moth to visit some twice.

But that would waste energy
and if we mark each flower

as the moth drinks from it,
it's clear that the moth,

somehow or other, never does this.

Hummingbird hawk moths have
no difficulty in hovering.

Bee hawks however,

have heavier bodies and
they sometimes use their legs

to help support themselves as they work.

Their need to keep drinking
is so pressing

that a female will continue
to do that even

when the male with whom she
is mating seems

to be trying to fly
in the opposite direction.

The Buddleia plant may be
a particular favorite

of hawk moths but it is,
of course, a foreigner,

introduced into our gardens
from China in the nineteenth century.

The hawk moth's original supplies
of nectar came

from the flowers of the meadows.

And they still feed there,

alongside many other insects.

This is a carpenter bee.

Bees also have two pairs of wings
but they are hooked together so,

like those of butterflies,
they operate as one.

Bumblebees have particularly large
and heavy bodies and flight,

for them, can be a real effort.

That's particularly so in spring
when the mornings are cold

and queen bumblebees are just emerging
from their winter sleep.

It's only a few degrees above freezing,

but a queen needs to get started early
to look for food.

The thick furry hairs
on her body help to conserve

what heat she manages to generate.

At the moment she's only
a few degrees warmer

than the surrounding vegetation -
as a thermal camera clearly shows.

Her body is only marginally more pink

than the blue leaves
and moss around her.

But she has a special way
of warming up for flight.

She can put her wings
out of gear so that,

without moving them,

she can revv up
the wing muscles inside -

and that raises the temperature
within her thorax

by twenty degrees centigrade
or even more -

as the expanding yellow image
on the thermal camera indicates.

Her body temperature
is now over 30 degrees centigrade.

At last, she has a chance of lift-off.

She will now be able to visit
the spring flowers

while it's still too cold
for others to do so.

The long trumpets of the daffodils
retain heat very well

and they're still warm even after
their hot-bodied visitors have left.

Flies, back in their distant
evolutionary past,

also had two pairs of wings,

but their back pair have been reduced
to simple knob-ended rods.

These are particularly long
on crane flies.

They're part of the fly's
flight instrumentation.

Microscopic sensors on their upper
and lower surfaces tell their owner

about the air currents around its body
and so help in flight control.

They start up even before take-off.

Flies are such accomplished flyers

that they can land upside-down
on a ceiling -

or, in this case,
the underside of a twig.

Only when you slow down
a fly's flight -

here by a hundred times -

can you fully appreciate
what superb aerial control they have.

Some species,
like these long-legged flies,

flaunt their wings in courtship,
just as damselflies do.

These dance flies are voracious hunters

and it's particularly important
for them

that they perform
their dance correctly.

If one doesn't get it right
its partner might well eat it.

This performance, however,
seems to have been up to standard.

For hoverflies -

arguably the most accomplished
of all insect aviators -

immaculate aerial control is
what makes a male attractive to a female.

A male lays claim to a mating territory
by trying to stay

in exactly the same position
in space for as long as possible.

That's not easy
when there are others all around you,

trying to do precisely the same thing.

It might seem
that he's absolutely motionless,

but in fact he's having
to make continual changes

to adjust for slight currents
in the air.

It's an amazing piece of acrobatics -

far better than anything
that we could do in a helicopter.

And it's all done in order
to impress the female -

to show her that he is superb
at holding his territory.

Having to chase away rivals that come
too close is an exhausting business -

and when you're trying to maintain your
hold on a particular point in mid-air,

even a small midge
has to be chased away.

After a morning spent doing this,

a male hoverfly may have lost
as much as a third of his body weight.

Little wonder that he takes a break
at mid-day in order to rest and refuel.

He dabs up nectar with mouth-parts
that are shaped like a pad.

Having refilled his fuel tank,

the male returns to his territory for
the afternoon's session of hovering,

in the hope of attracting yet
another female and mating with her.

Once again, with his superb eyesight,

he's ready to spot anything
that might whiz by him

at high speed that could be a female.

And I might just be able to
fool him with a pea-shooter.

Although there may seem to be
an extraordinarily large number

of different flies in the world,

it's actually the beetles that are
the most varied of all insect groups.

There are 300,000 species of them.

Most find their food by crawling
and burrowing on the ground

and to prevent their wings
from being damaged in the process,

they've turned the front pair
into protective shields.

Some, like weevils,

keep their wing-covers
permanently closed

and before take-off push their
functional wings out of special slits.

Ladybirds, like most other beetles,

raise their wing covers
and hold them clear

of the hind wings
throughout their flight.

The result could hardly
be called aerodynamic

and consequently their flight
is rather lumbering.

Blister beetles are scarcely
any better.

When a flight is over,

the hind wings have to be packed away
beneath the covers - a process

that can be so complex
that it demands all the skills

of a Japanese master of origami.

With flight playing a relatively
small part in their lives,

many beetles have grown very large.

This one, the titan beetle that lives
in the forests of the Amazon,

is almost certainly the biggest
of all insects.

I have to handle him
with considerable care

because those huge mandibles
at the front are,

powerful enough it's said,

to be able to cut straight
through a pencil.

He can fly, but he can't get
into the air from the ground.

He's too heavy to do that,
so he has to climb trees

and launch himself
into the air that way,

and that's why he's got
such powerful legs,

armed with sharp claws.

The titan is now known to be
the biggest of all beetles.

The champion is seven inches long
from the tip of

the mandibles to the tip of
its abdomen.

The larva of this great monster
has not yet been found

but it must be at least twice
as big as the beetle -

a really huge grub.

Beetles and many other
insects spend so much

of their lives as flightless larvae
that it'd be more accurate

to think of them as creatures
of the earth rather than the sky.

Flight for them -
as it is for the mayflies -

is a relatively brief episode
at the end of their lives.

These cicadas
in the eastern United States,

spend seventeen whole years
below ground,

sucking sap from tree roots.

And then - within a few days -
a whole population emerges.

There may be millions of them
in a single acre of land.

They clamber up the trees
whose roots have provided them

with sap for all
of those seventeen years.

And here they change
into their adult costume.

Now they have the wings
they need to search for a partner.

Empty larval cases cover
the tree trunks and the ground beneath.

And above, in the branches,
the millions have started to sing.

The noise is ear-splitting.

After seventeen years
of living underground,

the cicadas are now approaching
the climax of their lives,

and for the males, that means this.

The call is his way
of attracting a female.

The females reply
with a quite different sound.

A click made by flicking her wings -

so that's what the males are
listening out for.

I can imitate the female's wing flick
with a snap of my fingers -

and that causes them
to follow me anywhere;

because they're so determined
to find a female.

Now can I bring you back.

How about coming this way.

Oh! The noise is awful.
Come this way. Come on.

Yes, I can hear you.

Ooo. - Quite right.

At last, a male finds his partner
and as he does his call alters.

He's indicating to her
that after seventeen years

the time has come to get down
to business.

How do these cicadas
all emerge simultaneously

after seventeen long years?

Well, we know that they can appreciate
changes in the contents of tree sap,

so they're able to detect
the passing of a year.

But how do they count up to seventeen?
We have no idea.

But even if we did,

this surely would remain one of
the most astonishing,

amazing events in the insect world -

and it'll all be over in a couple of
weeks for another seventeen years.