Dragons & Damsels (2019) - full transcript
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(dramatic music)
Dragonflies and damselflies
have been around
for a very, very long time.
They watched our ancestors
crawl out of the water
and witnessed the rise
and fall of the dinosaurs.
They've flown over lakes and rivers
for the last 330 million years.
What is the secret of their
extraordinary success?
Perhaps it is because they're completely
at home in two worlds.
Below the surface their
larvae are deadly hunters.
And when they've eaten their fill
and grown to full size,
they crawl out of the lake,
change their shape and take to the air.
(body crinkling)
But that's only part of this story.
The real reason for their long reign
over Planet Earth can be
found in their daily lives,
in behavior as complex as that
of many birds and mammals,
yet normally unseen.
So let's spend the summer
by this particular lake and watch closely.
The little creatures really
do have the biggest stories
to tell in the world
of dragons and damsels.
(wings fluttering)
(water trickling)
(birds chirping)
(gentle music)
Late spring, and with the warming sun,
the lake is getting busy.
The reeds are alive with
dragonflies and damselflies.
A miniature soap opera is about to start.
And one if its brightest
stars is a little damselfly
with a big role to play
in the coming drama.
The common blue.
(pencil scraping)
(birds chirping)
(wings fluttering)
Common blues are both
very common and very blue.
(gentle music)
A color so intense it seems to
glow when it catches the sun.
And in the world of dragons and damsels,
common blues are real characters.
Damselflies are smaller and
daintier than dragonflies
but they have an attitude
way bigger than their size.
Common blues are always bickering
over the best lakeside viewpoints.
And their huge bulging
eyes enable them to hide
behind a single blade of grass
and still keep watch on the neighborhood.
A picture of peace and serenity.
But to survive here, a damselfly is going
to need more than those sharp eyes.
It needs equally sharp wits.
They may have brains less
than the size of a pinhead,
yet common blues lead a
surprisingly complex life.
(birds chirping)
Females are not such a brilliant blue,
but when one of them visits the
lake, she soon gets noticed.
There's no romance,
a male simply pounces on her
and with no ceremony, hooks up.
And this one has mated, just.
There's stiff competition
for any single lady.
And she doesn't stay single for long.
He clamps himself to her thorax
with claspers at the
very end of his abdomen.
So far, so good.
But now he has a problem.
His reproductive organs open
at the end of his abdomen
and so do hers.
So in this position,
he can't actually mate with her.
But he also has a second
set of reproductive organs.
A kind of holding pouch,
halfway up his body,
that he's already filled with sperm
from the main sex organs
at the tip of his tail.
But it will take some extraordinary agility
for the pair to consummate this union.
(gentle music)
The female now has to
swing her abdomen forward,
so that she can reach
up to collect the sperm
from his secondary organs.
And he tries to help her as much as he can.
There we are.
Now together, the mating couple
form a romantic heart shape.
But there's a ruthless
side to this tender moment.
(dramatic music)
The male's secondary sex organs are
not only storage pouches,
they also contain a device
unique to dragons and damsels.
(dramatic music)
It's a probe with two hooks on the end.
With this, he's able to scoop out any sperm
that she may have acquired
from her previous mating.
And so ensure that he will
be the father of her young.
And now, the male needs
her to lay her eggs quickly
before another male comes
along and scoops out his sperm.
He tries to lift off with
the female still attached.
But she seems reluctant to leave,
even with the male at full throttle.
(upbeat music)
(wings fluttering)
He tries to persuade her with
a sharp bite to the head.
But no, she's clearly not impressed
by him or his pickup technique.
And there are plenty of other males around.
All she has to do is to wait.
Here's another male.
(wings fluttering)
She nips her first partner's tail
and after all his effort, he gives up.
And she flies off with her new partner.
Males will jump on any female they spot.
But females are much more choosy.
Her former partner's sperm is scooped out
and the new couple fly off
together to lay their eggs.
(wings fluttering)
(birds chirping)
Undaunted, our lonely male sets out
to look for a more willing partner.
But he can't afford to be too preoccupied
with the opposite sex.
(dramatic music)
He really needs to watch where he's going.
It just isn't his day.
The wasp spider has built
her lethal trap in the reeds,
in an excellent spot to
ambush unwary damselflies.
And she wraps her victim
in a shroud of silk
to stop him struggling.
And his short life is over.
(birds chirping)
(spider munching)
A large lake like this is home
to more than 20 different kinds
of dragonflies and damselflies.
But not all of them will
spend their whole lives here.
Both dragons and damsels
are great travelers.
Fly high and covering long distance
in their search for water.
Their eyes can detect
polarized light reflected
by water surface, so they can spot a pond
from a long way off,
no matter how tiny it is.
This lily pond in a garden
might be small compared
to the lake, but it's been discovered
by these intrepid explorers.
A tiny realm,
reigned over by an emperor dragonfly.
(pencil scratching)
(gentle music)
Dragonflies are more powerful and agile
in the air than damselflies
and they defend their own territories
around lakes and ponds,
engaging rivals in aerial dogfights.
But this intruder is a female,
and the male dragonfly
finally realizes this.
So he now grabs her and hooks up in midair.
Now they must perform the same
gymnastics as damselflies.
They can even fly up together like this.
But after mating,
they separate and the female goes off
to find somewhere to lay eggs on her own.
(wings fluttering)
She lays her eggs inside ponds,
but she's very choosy about
picking exactly the right place.
The carefully tended lilies
in this ornamental pond are just right.
(wings fluttering)
Sometimes, in her quest
to give her eggs the
best chance of survival,
she decides that the
perfect place is a long way
below the surface of the water.
But she doesn't mind getting wet.
(birds chirping)
A dragonfly can tell a lot
about both water quality
and the submerged vegetation from the way
that polarized light is
reflected from the surface.
So although the whole
pond looks the same to us,
discerning emperors quickly hone in
on the most suitable spots.
And one egg-laying female
soon attracts others.
(upbeat music)
(wings fluttering)
The egg-laying emperor is noticed
by the local common blues
that also use the pond.
But why?
Are they just curious about
these lumbering monsters?
Possibly.
But back on the big lake,
where there are vast swarms of common blues
this behavior seems to be
much more than just curiosity.
(wings fluttering)
As soon as the female emperor lands
on floating vegetation to lay her eggs,
she's surrounded by clouds of common blues,
buzzing her, mobbing her, harassing her.
Even landing on her and biting.
Eventually it all gets too much
for the female emperor and she gives up.
Why do the common blues risk
their lives chasing a dragonfly
that is much bigger than them
and could easily kill them?
Probably because of what those
emperor eggs will become.
(water gurgling)
(somber music)
Eggs hatch into larvae and
emperor larvae are killers.
(dramatic music)
Lethal predators.
Damselflies larvae are right up there
at the top of their menu.
Those sharp eyes spot any movement.
And the emperor larva stalks
its lunch like a tiny cat.
Its are eyes are huge.
And both face forward.
So the larvae has a stereo vision.
It can judge its distance
from a target very precisely.
And when it's close enough,
it deploys its secret weapon,
jaws that can shoot out
an additional half length
of its body,
a long-range strike capability that,
for the damselfly larva
comes out of nowhere.
(dramatic music)
The jaw snap shut and
the damselfly is impaled
on sharp spines,
to be hauled in and chopped up
by a pair of serrated blades
before being swallowed.
(dramatic music)
It's hardly surprising that emperors
and common blues don't get
along with one another.
(water gurgling)
But don't feel too sorry for the damsels.
They also are killers
and use the same tricks
as the bigger dragons,
just on smaller prey.
Water hog lice, slow moving, abundant,
the perfect meal for a
growing damselfly larva.
(gentle music)
And damselfly larvae are just as stealthy
as their bigger relatives.
Softly, softly,
just waiting for the hog louse to move.
(louse crunching)
(gentle music)
(dramatic music)
The battlefield under the surface
of a tranquil pond is no
place for the fainthearted.
And there's something else
lurking down here too.
Something hidden in the
dead leaves on the lake bed.
(dramatic music)
The larvae of darter dragonflies.
Squat creatures that look
like bits of dead plants.
They are ambush predators
and well camouflaged.
But these larvae have stopped hunting.
They are about to join the emperors
and common blues in the air above.
(gentle music)
And even the ugliest larva
turns into a beautiful dragon.
A common darter dragonfly,
as elegant and colorful as any emperor.
(gentle music)
(birds chirping)
Like emperors, darters defend
territories around the lake.
But they do this in a different way.
Male emperors sometimes take
a rest on a convenient perch
but they spend most of
their lives on the wing.
They patrol their territories in the air,
hawking up and down, occasionally hovering,
to survey their domain
and check for intruders.
(dramatic music)
(wings fluttering)
(birds chirping)
Darters are less energetic.
They find a convenient perch to keep watch,
and every now and then fly off
to check out their territory,
often coming back to the very same spot.
(wings fluttering)
Sometimes they pick the
flimsiest of perches.
But they have the poise
and balance of a ballerina.
All dragonflies are
true masters of the air.
They can hover, rock steady.
(dramatic music)
They can fly backwards.
And turn on a dime.
(upbeat music)
All these extreme aerobatics depend
on very sophisticated wings.
Wings that have corrugations for strength
and complex patterns of
veins that allow each wing
to change its flapping angle
independently in flight.
But exactly how do dragonflies
achieve their aerial skill?
Ready when you are
Yep.
At the Royal Veterinary College in London,
scientists are trying to find out.
Here Richard Bomphrey uses smoke trails
to reveal the complex patterns
of airflow over the wings.
(wings fluttering)
(gentle music)
(lights clicking)
And he studies the way
wings move by filming them
from every angle with
multiple high-speed cameras
which slow down the action 80 times.
Well, that's a very nice
take-off sequence of this darter.
We can see that the wings twist
and they bend and they change in camber,
each of the four wings is
being driven independently.
So sometimes the fore
and the hind wings are
flapping together in phase.
And after a little while,
it switches to counter stroking,
that's flapping out of phase.
Now we have nine cameras here.
And what all those views allow us to do is
to make a three-dimensional
model of the dragonfly's body
and the wings as they undergo
all these shape changes,
the bending and the twisting
so we can begin to understand
how the dragonfly controls its flight.
(gentle music)
If we now understand
how dragonflies achieve
such mastery of the air,
can we do any better?
(wings fluttering)
Scientist at Festo in
Esslingen, Germany, have tried.
A team of engineers here
spent many years trying
to build a robotic dragonfly
that mimics the dragonfly's natural flight
as Elias Knubben explains.
We tried to come as close
as possible to the real dragonfly.
We did a lot of research,
how do they adjust to
different surroundings,
how do they steer?
And I think we came quite
close to the functions.
We are able to control the
movements really precisely.
It has to be adjusted in
really very short times,
it's only milliseconds actually,
that you have time to react.
(wings fluttering)
(gentle music)
Festo's robo dragonfly can fly.
But it takes a skillful pilot,
controlling it remotely
just to keep it in the air,
let alone make it turn and twist
as elegantly as the real thing.
(gentle music)
The pilot has to control
nine different aspects
of the wings at the same time.
Far more complex than flying a helicopter.
Yet real dragonflies do this
with a brain the size of a pinhead.
This robot dragonfly is
an amazing achievement,
but it still doesn't come close
to matching a real dragonfly.
To be honest real nature
is even much better.
It's not really only, pretty much smaller.
But it's also,
it has even much more functions
and there's so much more to learn.
We're looking forward to do this.
(wings whirring)
But to be fair to Festo's engineers,
real dragonflies have been
practicing the art of flight
for 330 millions longer than they have.
And in that time, nature has come up
with more uses for wings than just flying.
(gentle music)
These particularly beautiful wings,
with deep blue patches,
belong to a banded damoiselle.
(pencil scratching)
Banded damoiselles avoid the busy lake.
They prefer flowing water
and live on a nearby river.
(birds chirping)
Unlike most damselflies,
banded damoiselle males occupy
small territories strung out
along the banks of the river.
And they defend them in style,
(gentle music)
by flicking their wings,
showing off their colors
and so signaling ownership
of their exclusive riverside property.
Not all banded damoiselles
are created equal.
The wing spots vary in size.
This can be hard for us humans to spot,
even comparing museum
specimens side by side.
But the difference are quickly picked out
by those sharp damselfly eyes.
(wings fluttering)
(gentle music)
The fittest males have the biggest spots.
An arrival with smaller
spots soon realizes his place
and gives in gracefully.
But if a male with similar size spots tries
to take over the territory,
a different strategy is needed.
A fight with an equal could be dangerous.
It's better to just behave like gentlemen.
So each male shows off his spots
with exaggerated wing beats,
until one of them finally
accepts defeat and retreats.
(wings fluttering)
(gentle music)
Often, other males from
neighboring territories join in,
and they all sort out
the neighborhood hierarchy
between themselves.
For an insect,
this is really sophisticated behavior.
Each male is able to decide
the best strategy to follow,
based on his estimation of
the toughness of a rival.
(train whistling)
(birds chirping)
(wheels clacking)
(gentle music)
Summer is now reaching its height.
(birds chirping)
And back on the big lake,
more and more dragons and
damsels crowd into the reeds.
(wings fluttering)
These are four spotted chaser dragonflies
and they gather in huge
roosts every evening
to wake at dawn ready to find somewhere
to claim as their territory.
Not easy when there are so many rivals.
(wings fluttering)
(birds chirping)
Space in the reeds is now at a premium.
But that's not a problem
for another species
of damselfly that has
now joined the throng.
The common red-eye.
(upbeat music)
Red-eyes perch on anything floating
on the surface, not matter how small.
Each a captain of its own little ship
as it drifts over the surface of the lake.
(birds chirping)
(wings fluttering)
But they also sometimes get unwitting help
from bigger residents of the lake.
The feather from a swan
makes an excellent raft.
(birds chirping)
And the red-eyes defend their little boats
against the ever inquisitive common blues.
A flick of the wings, a warning,
there's no more room on board.
(wings fluttering)
(birds chirping)
And there's not much
more space in the reeds,
now crowded with males, just hanging out,
waiting for a female to turn up.
(gentle music)
And when one does,
she turns a lot of heads.
(wings fluttering)
With the season in full swing,
there's a lot of desperate males around.
A female common blue
and she seems available.
But this is an azure
damselfly, trying it on.
He might look like a common blue,
but he's a totally different species
and he simply can't hook up.
Now a red-eye tries his luck.
This is definitely not going to work.
Finally a genuine common blue
and her patience is rewarded.
(wings fluttering)
In these crowded skies,
a male has only one mission.
To attach himself to a
female and stay attached.
It's the best way
to avoid another male
mating with his partner.
But it looks like hard work for the female.
Though her male does have his uses.
(wings fluttering)
To find the best spot to lay her eggs,
a female damsel must sometimes
submerge herself completely.
(dramatic music)
Being smaller than dragonflies,
she can get trapped by the
surface tension of the water.
The male, however,
stays dry above the surface.
And that can be important.
He may be needed to haul
her out of the water
if she gets into difficulties.
(wings fluttering)
(dramatic music)
But if the female gets too wet,
even the male's assistance
may not be enough.
Males don't like getting wet.
And if a female submerges
particularly deeply,
her mate just abandons her to her fate.
(water gurgling)
Now, she's on her own.
Without a male to help,
it's a real struggle to
clamber back out of the water.
As long as a male stays
attached to his partner,
no other male can steal her
and he can be sure that he will
be the father of those eggs.
But all these single
males don't just give up.
They constantly hassle egg-laying pairs.
And if a pair crashes onto the surface,
the male might drop his
mate before he gets soaked,
and then one of the single
males can grab the female.
(wings fluttering)
But this time,
they've picked an unusually feisty male.
He hangs on, even though he's now stuck
on the surface film himself.
They're so busy fighting over the female
they're getting careless
and all this activity
attracts the attention
of monsters from the deep.
(dramatic music)
(water splashing)
Trout snatch up anything
edible trapped on the surface.
This male has somehow
avoided becoming fish food.
But that was his good
luck used up for the day.
(dramatic music)
His struggles create ripples
and for the creatures that
live on the surface film,
that is like sounding a dinner bell.
(dramatic music)
Pond skaters can detect these vibrations
and pinpoint their source precisely.
(dramatic music)
Swarms of then hone in
on the helpless damsel.
(wings fluttering)
They pierce the damselfly's skin
with their sharp mouthparts,
inject a digestive toxin
and then suck up nutritious dragonfly soup.
(pond skater slurping)
(dramatic music)
(wing fluttering)
Great flotillas of pond skaters
patrol the lake's surface.
(flies buzzing)
And they're never short of food.
For the female damsels have
to settle there if
they're to lay their eggs.
But both dragons and damsels spend
as little time as
possible near the surface.
(wings fluttering)
Darters, however,
manage to lay their eggs in flight,
just touching the water briefly.
Darters do this as a pair,
a display of precision flying
that human engineers can only dream of.
(gentle music)
With each dip,
the female releases a few eggs.
Eight wings and two
brains working together.
The slightest miscalculation
would end in disaster.
Damselflies have a different strategy
to avoid the dangers of the lake.
Egg-laying pairs,
like these azure damselflies,
often gather in large numbers.
So there's less chance of
being the unlucky couple
if a predator does show up.
(flies buzzing)
(wings fluttering)
This male has sensed something is wrong
and is desperately trying to
pull his mate from the water.
But however much he
flaps, he can't take off.
(dramatic music)
And this is why.
An underwater predator,
attracted by the crowds
of busy damselflies,
has bitten off her abdomen
and made a meal of it.
Her mate is still trying to rescue her
and fly her to safety.
But it's too late.
(gentle music)
(wings fluttering)
The others carry on egg laying
as if nothing has happened,
paying no attention to the unlucky female
who just manages to haul
herself onto a lily leaf.
Always on the lookout for a single lady,
a common blue thinks he's
found an opportunity.
But soon realizes his mistake.
She is mortally injured and beyond rescue.
(somber music)
(thunder rumbling)
(gentle music)
For these tiny creatures,
raindrops are as dangerous as cannonballs.
(rain dripping)
Time to find shelter.
(thunder rumbling)
But the season is nearly
over and time is precious.
As soon as the sun returns,
male damoiselles are back
on their territories.
It's now almost autumn,
and while other damsels
and dragons are winding down,
one kind of damselfly
is just getting started.
An unusual species that's
attracted a lot of attention
in recent years, the willow emerald.
In the last few decades,
this species has moved
steadily north through Europe
and has even made the hop
across the North Sea and invaded England.
The British Dragonfly Society
have been keeping a keen eye
on the spread of these invaders,
as Fiona McKenna explains.
The willow emerald damselfly
arrived in roughly 2007 is
when we got the first record
of a female in the UK.
Their rapid invasion
of Northern Europe is a
consequence of climate change
which is why it's important
for scientists and naturalists
to chart its spread.
It's a marker that can tell us
how a warmer climate might
effect the natural world.
And the spread of the
willow emerald is easy
to track because of
their strange lifestyle.
It's quite unusual,
it's different to other damselflies.
You have to look up in trees for it.
Traditionally it's associated with willow,
hence it being called willow emerald.
But it has been known to utilize
other types of trees as well.
And it also lays its eggs into bark,
so it's got very unusual
egg-laying behavior.
(gentle music)
The female has sharp blades at the tip
of her abdomen which she uses
to cut holes in the bark of trees.
They leave very distinctive
little oval scars
where they've laid their eggs into.
The scarred branches are easy to see.
So you don't even need
to identify the damselflies themselves
to follow the species spread northwards.
Of all the dragons and damsels,
willow emeralds are among
the last to take to the wing.
And they must work quickly
before the frost arrives.
(gentle music)
Autumn brings the stories
of all dragonflies and
damselflies to a close.
Lakes and rivers seem deserted.
But not so.
Below the surface, the next generation,
the legacy of those frantic
matings of summer are waiting,
ready to take to the air
when the weather warms again
as they have done for the
last 330 million years.
(upbeat music)
---
(dramatic music)
Dragonflies and damselflies
have been around
for a very, very long time.
They watched our ancestors
crawl out of the water
and witnessed the rise
and fall of the dinosaurs.
They've flown over lakes and rivers
for the last 330 million years.
What is the secret of their
extraordinary success?
Perhaps it is because they're completely
at home in two worlds.
Below the surface their
larvae are deadly hunters.
And when they've eaten their fill
and grown to full size,
they crawl out of the lake,
change their shape and take to the air.
(body crinkling)
But that's only part of this story.
The real reason for their long reign
over Planet Earth can be
found in their daily lives,
in behavior as complex as that
of many birds and mammals,
yet normally unseen.
So let's spend the summer
by this particular lake and watch closely.
The little creatures really
do have the biggest stories
to tell in the world
of dragons and damsels.
(wings fluttering)
(water trickling)
(birds chirping)
(gentle music)
Late spring, and with the warming sun,
the lake is getting busy.
The reeds are alive with
dragonflies and damselflies.
A miniature soap opera is about to start.
And one if its brightest
stars is a little damselfly
with a big role to play
in the coming drama.
The common blue.
(pencil scraping)
(birds chirping)
(wings fluttering)
Common blues are both
very common and very blue.
(gentle music)
A color so intense it seems to
glow when it catches the sun.
And in the world of dragons and damsels,
common blues are real characters.
Damselflies are smaller and
daintier than dragonflies
but they have an attitude
way bigger than their size.
Common blues are always bickering
over the best lakeside viewpoints.
And their huge bulging
eyes enable them to hide
behind a single blade of grass
and still keep watch on the neighborhood.
A picture of peace and serenity.
But to survive here, a damselfly is going
to need more than those sharp eyes.
It needs equally sharp wits.
They may have brains less
than the size of a pinhead,
yet common blues lead a
surprisingly complex life.
(birds chirping)
Females are not such a brilliant blue,
but when one of them visits the
lake, she soon gets noticed.
There's no romance,
a male simply pounces on her
and with no ceremony, hooks up.
And this one has mated, just.
There's stiff competition
for any single lady.
And she doesn't stay single for long.
He clamps himself to her thorax
with claspers at the
very end of his abdomen.
So far, so good.
But now he has a problem.
His reproductive organs open
at the end of his abdomen
and so do hers.
So in this position,
he can't actually mate with her.
But he also has a second
set of reproductive organs.
A kind of holding pouch,
halfway up his body,
that he's already filled with sperm
from the main sex organs
at the tip of his tail.
But it will take some extraordinary agility
for the pair to consummate this union.
(gentle music)
The female now has to
swing her abdomen forward,
so that she can reach
up to collect the sperm
from his secondary organs.
And he tries to help her as much as he can.
There we are.
Now together, the mating couple
form a romantic heart shape.
But there's a ruthless
side to this tender moment.
(dramatic music)
The male's secondary sex organs are
not only storage pouches,
they also contain a device
unique to dragons and damsels.
(dramatic music)
It's a probe with two hooks on the end.
With this, he's able to scoop out any sperm
that she may have acquired
from her previous mating.
And so ensure that he will
be the father of her young.
And now, the male needs
her to lay her eggs quickly
before another male comes
along and scoops out his sperm.
He tries to lift off with
the female still attached.
But she seems reluctant to leave,
even with the male at full throttle.
(upbeat music)
(wings fluttering)
He tries to persuade her with
a sharp bite to the head.
But no, she's clearly not impressed
by him or his pickup technique.
And there are plenty of other males around.
All she has to do is to wait.
Here's another male.
(wings fluttering)
She nips her first partner's tail
and after all his effort, he gives up.
And she flies off with her new partner.
Males will jump on any female they spot.
But females are much more choosy.
Her former partner's sperm is scooped out
and the new couple fly off
together to lay their eggs.
(wings fluttering)
(birds chirping)
Undaunted, our lonely male sets out
to look for a more willing partner.
But he can't afford to be too preoccupied
with the opposite sex.
(dramatic music)
He really needs to watch where he's going.
It just isn't his day.
The wasp spider has built
her lethal trap in the reeds,
in an excellent spot to
ambush unwary damselflies.
And she wraps her victim
in a shroud of silk
to stop him struggling.
And his short life is over.
(birds chirping)
(spider munching)
A large lake like this is home
to more than 20 different kinds
of dragonflies and damselflies.
But not all of them will
spend their whole lives here.
Both dragons and damsels
are great travelers.
Fly high and covering long distance
in their search for water.
Their eyes can detect
polarized light reflected
by water surface, so they can spot a pond
from a long way off,
no matter how tiny it is.
This lily pond in a garden
might be small compared
to the lake, but it's been discovered
by these intrepid explorers.
A tiny realm,
reigned over by an emperor dragonfly.
(pencil scratching)
(gentle music)
Dragonflies are more powerful and agile
in the air than damselflies
and they defend their own territories
around lakes and ponds,
engaging rivals in aerial dogfights.
But this intruder is a female,
and the male dragonfly
finally realizes this.
So he now grabs her and hooks up in midair.
Now they must perform the same
gymnastics as damselflies.
They can even fly up together like this.
But after mating,
they separate and the female goes off
to find somewhere to lay eggs on her own.
(wings fluttering)
She lays her eggs inside ponds,
but she's very choosy about
picking exactly the right place.
The carefully tended lilies
in this ornamental pond are just right.
(wings fluttering)
Sometimes, in her quest
to give her eggs the
best chance of survival,
she decides that the
perfect place is a long way
below the surface of the water.
But she doesn't mind getting wet.
(birds chirping)
A dragonfly can tell a lot
about both water quality
and the submerged vegetation from the way
that polarized light is
reflected from the surface.
So although the whole
pond looks the same to us,
discerning emperors quickly hone in
on the most suitable spots.
And one egg-laying female
soon attracts others.
(upbeat music)
(wings fluttering)
The egg-laying emperor is noticed
by the local common blues
that also use the pond.
But why?
Are they just curious about
these lumbering monsters?
Possibly.
But back on the big lake,
where there are vast swarms of common blues
this behavior seems to be
much more than just curiosity.
(wings fluttering)
As soon as the female emperor lands
on floating vegetation to lay her eggs,
she's surrounded by clouds of common blues,
buzzing her, mobbing her, harassing her.
Even landing on her and biting.
Eventually it all gets too much
for the female emperor and she gives up.
Why do the common blues risk
their lives chasing a dragonfly
that is much bigger than them
and could easily kill them?
Probably because of what those
emperor eggs will become.
(water gurgling)
(somber music)
Eggs hatch into larvae and
emperor larvae are killers.
(dramatic music)
Lethal predators.
Damselflies larvae are right up there
at the top of their menu.
Those sharp eyes spot any movement.
And the emperor larva stalks
its lunch like a tiny cat.
Its are eyes are huge.
And both face forward.
So the larvae has a stereo vision.
It can judge its distance
from a target very precisely.
And when it's close enough,
it deploys its secret weapon,
jaws that can shoot out
an additional half length
of its body,
a long-range strike capability that,
for the damselfly larva
comes out of nowhere.
(dramatic music)
The jaw snap shut and
the damselfly is impaled
on sharp spines,
to be hauled in and chopped up
by a pair of serrated blades
before being swallowed.
(dramatic music)
It's hardly surprising that emperors
and common blues don't get
along with one another.
(water gurgling)
But don't feel too sorry for the damsels.
They also are killers
and use the same tricks
as the bigger dragons,
just on smaller prey.
Water hog lice, slow moving, abundant,
the perfect meal for a
growing damselfly larva.
(gentle music)
And damselfly larvae are just as stealthy
as their bigger relatives.
Softly, softly,
just waiting for the hog louse to move.
(louse crunching)
(gentle music)
(dramatic music)
The battlefield under the surface
of a tranquil pond is no
place for the fainthearted.
And there's something else
lurking down here too.
Something hidden in the
dead leaves on the lake bed.
(dramatic music)
The larvae of darter dragonflies.
Squat creatures that look
like bits of dead plants.
They are ambush predators
and well camouflaged.
But these larvae have stopped hunting.
They are about to join the emperors
and common blues in the air above.
(gentle music)
And even the ugliest larva
turns into a beautiful dragon.
A common darter dragonfly,
as elegant and colorful as any emperor.
(gentle music)
(birds chirping)
Like emperors, darters defend
territories around the lake.
But they do this in a different way.
Male emperors sometimes take
a rest on a convenient perch
but they spend most of
their lives on the wing.
They patrol their territories in the air,
hawking up and down, occasionally hovering,
to survey their domain
and check for intruders.
(dramatic music)
(wings fluttering)
(birds chirping)
Darters are less energetic.
They find a convenient perch to keep watch,
and every now and then fly off
to check out their territory,
often coming back to the very same spot.
(wings fluttering)
Sometimes they pick the
flimsiest of perches.
But they have the poise
and balance of a ballerina.
All dragonflies are
true masters of the air.
They can hover, rock steady.
(dramatic music)
They can fly backwards.
And turn on a dime.
(upbeat music)
All these extreme aerobatics depend
on very sophisticated wings.
Wings that have corrugations for strength
and complex patterns of
veins that allow each wing
to change its flapping angle
independently in flight.
But exactly how do dragonflies
achieve their aerial skill?
Ready when you are
Yep.
At the Royal Veterinary College in London,
scientists are trying to find out.
Here Richard Bomphrey uses smoke trails
to reveal the complex patterns
of airflow over the wings.
(wings fluttering)
(gentle music)
(lights clicking)
And he studies the way
wings move by filming them
from every angle with
multiple high-speed cameras
which slow down the action 80 times.
Well, that's a very nice
take-off sequence of this darter.
We can see that the wings twist
and they bend and they change in camber,
each of the four wings is
being driven independently.
So sometimes the fore
and the hind wings are
flapping together in phase.
And after a little while,
it switches to counter stroking,
that's flapping out of phase.
Now we have nine cameras here.
And what all those views allow us to do is
to make a three-dimensional
model of the dragonfly's body
and the wings as they undergo
all these shape changes,
the bending and the twisting
so we can begin to understand
how the dragonfly controls its flight.
(gentle music)
If we now understand
how dragonflies achieve
such mastery of the air,
can we do any better?
(wings fluttering)
Scientist at Festo in
Esslingen, Germany, have tried.
A team of engineers here
spent many years trying
to build a robotic dragonfly
that mimics the dragonfly's natural flight
as Elias Knubben explains.
We tried to come as close
as possible to the real dragonfly.
We did a lot of research,
how do they adjust to
different surroundings,
how do they steer?
And I think we came quite
close to the functions.
We are able to control the
movements really precisely.
It has to be adjusted in
really very short times,
it's only milliseconds actually,
that you have time to react.
(wings fluttering)
(gentle music)
Festo's robo dragonfly can fly.
But it takes a skillful pilot,
controlling it remotely
just to keep it in the air,
let alone make it turn and twist
as elegantly as the real thing.
(gentle music)
The pilot has to control
nine different aspects
of the wings at the same time.
Far more complex than flying a helicopter.
Yet real dragonflies do this
with a brain the size of a pinhead.
This robot dragonfly is
an amazing achievement,
but it still doesn't come close
to matching a real dragonfly.
To be honest real nature
is even much better.
It's not really only, pretty much smaller.
But it's also,
it has even much more functions
and there's so much more to learn.
We're looking forward to do this.
(wings whirring)
But to be fair to Festo's engineers,
real dragonflies have been
practicing the art of flight
for 330 millions longer than they have.
And in that time, nature has come up
with more uses for wings than just flying.
(gentle music)
These particularly beautiful wings,
with deep blue patches,
belong to a banded damoiselle.
(pencil scratching)
Banded damoiselles avoid the busy lake.
They prefer flowing water
and live on a nearby river.
(birds chirping)
Unlike most damselflies,
banded damoiselle males occupy
small territories strung out
along the banks of the river.
And they defend them in style,
(gentle music)
by flicking their wings,
showing off their colors
and so signaling ownership
of their exclusive riverside property.
Not all banded damoiselles
are created equal.
The wing spots vary in size.
This can be hard for us humans to spot,
even comparing museum
specimens side by side.
But the difference are quickly picked out
by those sharp damselfly eyes.
(wings fluttering)
(gentle music)
The fittest males have the biggest spots.
An arrival with smaller
spots soon realizes his place
and gives in gracefully.
But if a male with similar size spots tries
to take over the territory,
a different strategy is needed.
A fight with an equal could be dangerous.
It's better to just behave like gentlemen.
So each male shows off his spots
with exaggerated wing beats,
until one of them finally
accepts defeat and retreats.
(wings fluttering)
(gentle music)
Often, other males from
neighboring territories join in,
and they all sort out
the neighborhood hierarchy
between themselves.
For an insect,
this is really sophisticated behavior.
Each male is able to decide
the best strategy to follow,
based on his estimation of
the toughness of a rival.
(train whistling)
(birds chirping)
(wheels clacking)
(gentle music)
Summer is now reaching its height.
(birds chirping)
And back on the big lake,
more and more dragons and
damsels crowd into the reeds.
(wings fluttering)
These are four spotted chaser dragonflies
and they gather in huge
roosts every evening
to wake at dawn ready to find somewhere
to claim as their territory.
Not easy when there are so many rivals.
(wings fluttering)
(birds chirping)
Space in the reeds is now at a premium.
But that's not a problem
for another species
of damselfly that has
now joined the throng.
The common red-eye.
(upbeat music)
Red-eyes perch on anything floating
on the surface, not matter how small.
Each a captain of its own little ship
as it drifts over the surface of the lake.
(birds chirping)
(wings fluttering)
But they also sometimes get unwitting help
from bigger residents of the lake.
The feather from a swan
makes an excellent raft.
(birds chirping)
And the red-eyes defend their little boats
against the ever inquisitive common blues.
A flick of the wings, a warning,
there's no more room on board.
(wings fluttering)
(birds chirping)
And there's not much
more space in the reeds,
now crowded with males, just hanging out,
waiting for a female to turn up.
(gentle music)
And when one does,
she turns a lot of heads.
(wings fluttering)
With the season in full swing,
there's a lot of desperate males around.
A female common blue
and she seems available.
But this is an azure
damselfly, trying it on.
He might look like a common blue,
but he's a totally different species
and he simply can't hook up.
Now a red-eye tries his luck.
This is definitely not going to work.
Finally a genuine common blue
and her patience is rewarded.
(wings fluttering)
In these crowded skies,
a male has only one mission.
To attach himself to a
female and stay attached.
It's the best way
to avoid another male
mating with his partner.
But it looks like hard work for the female.
Though her male does have his uses.
(wings fluttering)
To find the best spot to lay her eggs,
a female damsel must sometimes
submerge herself completely.
(dramatic music)
Being smaller than dragonflies,
she can get trapped by the
surface tension of the water.
The male, however,
stays dry above the surface.
And that can be important.
He may be needed to haul
her out of the water
if she gets into difficulties.
(wings fluttering)
(dramatic music)
But if the female gets too wet,
even the male's assistance
may not be enough.
Males don't like getting wet.
And if a female submerges
particularly deeply,
her mate just abandons her to her fate.
(water gurgling)
Now, she's on her own.
Without a male to help,
it's a real struggle to
clamber back out of the water.
As long as a male stays
attached to his partner,
no other male can steal her
and he can be sure that he will
be the father of those eggs.
But all these single
males don't just give up.
They constantly hassle egg-laying pairs.
And if a pair crashes onto the surface,
the male might drop his
mate before he gets soaked,
and then one of the single
males can grab the female.
(wings fluttering)
But this time,
they've picked an unusually feisty male.
He hangs on, even though he's now stuck
on the surface film himself.
They're so busy fighting over the female
they're getting careless
and all this activity
attracts the attention
of monsters from the deep.
(dramatic music)
(water splashing)
Trout snatch up anything
edible trapped on the surface.
This male has somehow
avoided becoming fish food.
But that was his good
luck used up for the day.
(dramatic music)
His struggles create ripples
and for the creatures that
live on the surface film,
that is like sounding a dinner bell.
(dramatic music)
Pond skaters can detect these vibrations
and pinpoint their source precisely.
(dramatic music)
Swarms of then hone in
on the helpless damsel.
(wings fluttering)
They pierce the damselfly's skin
with their sharp mouthparts,
inject a digestive toxin
and then suck up nutritious dragonfly soup.
(pond skater slurping)
(dramatic music)
(wing fluttering)
Great flotillas of pond skaters
patrol the lake's surface.
(flies buzzing)
And they're never short of food.
For the female damsels have
to settle there if
they're to lay their eggs.
But both dragons and damsels spend
as little time as
possible near the surface.
(wings fluttering)
Darters, however,
manage to lay their eggs in flight,
just touching the water briefly.
Darters do this as a pair,
a display of precision flying
that human engineers can only dream of.
(gentle music)
With each dip,
the female releases a few eggs.
Eight wings and two
brains working together.
The slightest miscalculation
would end in disaster.
Damselflies have a different strategy
to avoid the dangers of the lake.
Egg-laying pairs,
like these azure damselflies,
often gather in large numbers.
So there's less chance of
being the unlucky couple
if a predator does show up.
(flies buzzing)
(wings fluttering)
This male has sensed something is wrong
and is desperately trying to
pull his mate from the water.
But however much he
flaps, he can't take off.
(dramatic music)
And this is why.
An underwater predator,
attracted by the crowds
of busy damselflies,
has bitten off her abdomen
and made a meal of it.
Her mate is still trying to rescue her
and fly her to safety.
But it's too late.
(gentle music)
(wings fluttering)
The others carry on egg laying
as if nothing has happened,
paying no attention to the unlucky female
who just manages to haul
herself onto a lily leaf.
Always on the lookout for a single lady,
a common blue thinks he's
found an opportunity.
But soon realizes his mistake.
She is mortally injured and beyond rescue.
(somber music)
(thunder rumbling)
(gentle music)
For these tiny creatures,
raindrops are as dangerous as cannonballs.
(rain dripping)
Time to find shelter.
(thunder rumbling)
But the season is nearly
over and time is precious.
As soon as the sun returns,
male damoiselles are back
on their territories.
It's now almost autumn,
and while other damsels
and dragons are winding down,
one kind of damselfly
is just getting started.
An unusual species that's
attracted a lot of attention
in recent years, the willow emerald.
In the last few decades,
this species has moved
steadily north through Europe
and has even made the hop
across the North Sea and invaded England.
The British Dragonfly Society
have been keeping a keen eye
on the spread of these invaders,
as Fiona McKenna explains.
The willow emerald damselfly
arrived in roughly 2007 is
when we got the first record
of a female in the UK.
Their rapid invasion
of Northern Europe is a
consequence of climate change
which is why it's important
for scientists and naturalists
to chart its spread.
It's a marker that can tell us
how a warmer climate might
effect the natural world.
And the spread of the
willow emerald is easy
to track because of
their strange lifestyle.
It's quite unusual,
it's different to other damselflies.
You have to look up in trees for it.
Traditionally it's associated with willow,
hence it being called willow emerald.
But it has been known to utilize
other types of trees as well.
And it also lays its eggs into bark,
so it's got very unusual
egg-laying behavior.
(gentle music)
The female has sharp blades at the tip
of her abdomen which she uses
to cut holes in the bark of trees.
They leave very distinctive
little oval scars
where they've laid their eggs into.
The scarred branches are easy to see.
So you don't even need
to identify the damselflies themselves
to follow the species spread northwards.
Of all the dragons and damsels,
willow emeralds are among
the last to take to the wing.
And they must work quickly
before the frost arrives.
(gentle music)
Autumn brings the stories
of all dragonflies and
damselflies to a close.
Lakes and rivers seem deserted.
But not so.
Below the surface, the next generation,
the legacy of those frantic
matings of summer are waiting,
ready to take to the air
when the weather warms again
as they have done for the
last 330 million years.
(upbeat music)