North America the Mississippi river.
Its July and the afternoon is still very hot.
People here dread this kind of day at this time of year.
They brace themselves.
Because it is happening again.
All afternoon they've risen out of the water
mayflies invade the city in their millions in their billions.
For the last year
they existed ad grubs feeding in the mud at the bottom of the river
building up energy for this one day.
At dusk they take to the air.
This is a dance of life and death
there is only one reason to fly to mate.
And this is their only chance tomorrow the will all be dead.
They can't even eat
adult mayflies have no mouthparts.
With only enough energy to fly once and mate
they crash onto the water surface
pouring out their cargo of eggs as they die.
From this final act comes a stream of new life a continuing story
unbroken for nearly four hundred million years.
And in that four hundred million years
the biggest problem mayflies have face is a recent one.
Humans have built cities on their river.
Cities with bright lights that draw them away from the dance
so that they die without ever laying their eggs.
The night leaves a scene of devastation
their bodies litter the roads
and bridges and clog up machinery.
Less than a day after they emerged from the river
every single mayfly is dead.
They had only one reason for living and may of them failed.
It all seems so printless even tragic
but each mayfly was just an insect being an insect
its only purpose in life to make more insects.
More and more
And all insects are as dedicated to this cause as mayflies.
This is a moth.
At least mayflies get to fly
but a female vapourer moth doesn't even have wings
she's just a bag of eggs.
She mated once with a passing winged male
who then flew away leaving her to spend her whole adult life
in an area not much bigger than a postage stamp.
Most insects lay hundreds of eggs in the hope that a few will survive.
Every egg has its own fleeting moment maternal care and attention
but once in place the eggs
are left to hatch or not by themselves.
But even though their mother is probably dead by now
she has given them the best start she could
each egg is a microscopic survival capsule.
Most are smaller than a pinhead yet every different kind of insect egg
is a unique an intricate sculpture.
Vast numbers of eggs are an insurance against disaster
but if it weren't for these disasters insects would overwhelm the planet.
Flies for example breed every few week
if this pair were to breed
and all their descendents survived and bred for a year
the resulting ball of maggots would be as big as the Earth.
more than enough bait for a whole nation of fishermen.
But nature has a way of keeping things in check
predators competitors disease
flies die like flies.
Its only when human meddle with nature
that they unleash the real power of insects to make more insects.
If a fisherman say
put a tray of maggot in a fridge expecting the cold
to keep them subdued until he got back from holiday
and if just after he left for the airport a fuse blew.
the fridge would warm up nicely
and there would be nothing to stop all the maggots
turning into blue bottle flies.
In a matter of days each one of these
will produce a thousand new maggots an unpleasant welcome home
with such huge numbers mayflies and bluebottle flies
have no problem finding a mate but its now that simple for everyone.
A derelict warehouse in north America is a huge three dimensional space
so how can a lone silk moth hope to find a mate here?
Silk moths have been introduced from the rainforest of Asia
a place just as big and complicated.
And there they developed a system
that works however complex the surroundings.
She advertises herself with scent
a special chemical
a pheromone released from a gland on her abdomen.
The scent consists of long molecules with a particular shape.
These are only recognized by this kind of moth.
They fit like a key in a lock into special receptors
on the male moth's antennae.
His antennae are so sensitive
it only takes a dozen molecules to excite him
he could detect her a mile away.
By flying upwind and tacking across the waves of scent
he moves in her general direction.
As he gets closer
the scent gets stronger
and the waves turn into a flood.
She could be anywhere here
it seems like she is everywhere.
He's overwhelmed
he knows he is very close but he has to find her as best he can.
The do finally get to mate but scent is most effective over long distances.
At short ranges it can be confusing
which is why this polka dot moth in the deep south of the USA
has developed a separate short range system as well.
A male moth homes in on a female's scent
She avoids any last minute confusion
by switching to a finer signal a beam of sound.
Not that humans would recognize it as sound
the moth's music is pitched seven octaves
above human hearing moths hear in ultrasound.
She gives him precise directions with a medley of ultrasonic clicks.
As he closes in he clicks back
The problem with broadcasting sound though
is that some predators can also tune in.
These brightly coloured moths are very poisonous
they don't care who else hears their broadcast.
But more appetizing insects need a secure channel.
Leaf hopper are not poisonous
so when they use sound
it has to be as private as a phone call.
They transmit vibrations through their legs to the plant stems
and the sound is received by touch.
In other words leafhoppers hear with their feet.
The males move from plant to plant calling
and listening for females of their own kind.
They've not distracted by sounds in the human world
and humans are completely unaware
that their garden plants are alive with secret music.
Some insects are not as shy
they've songs are so amplified that humans cannot fail to hear them.
The world's loudest singers live in Australia.
Distant relatives of leafhoppers cicadas.
A cicada sings by clicking membranes in his absomen back and forth.
His song can be heard half a mile away.
But to a predator wanting to hunt him down
his song seems to come from a different bush.
Hes not only loud he's a ventriloquist.
Once they get going some cicadas can sing at 120 decibels
enough to drown out a pneumatic drill.
Double drummer cicadas are the loudest insects in the world
but not far behind are "greengrocers"
"yellow Mondays" "black princes" "cherry noses".
And they all live in Sydney.
No wonder that in the din of summer many people move away for the season.
Some insects use vision to find a mate they've attracted by simple good looks.
A female jewel beetles flaunts her golden dimpled wing casing
which is irresistible to a male.
It's also big with him is beautiful
But in recent years
males have discovered other distractions.
For a male jewel beetle it's the simple things
that are exciting if its orange and dimpled
then its just what he is looking for.
And enormous this must be a super female
a jewel beetle goddess.
Certain beer bottles have just the right colour and texture
all the males in the area are besotted.
The real females are ignored.
With so many males on the bottle the beetles were in danger of extinction
until the breweries began redesigning their bottles
hoping the males would spend some time with their females.
A male walnut fly also has a simple goal in life.
He has to hay claim to a blemish on the surface of a walnut.
Its not easy other males will challenge him.
Every male knows that a female fly needs to lay her eggs inside the hard shell
but she can only pierce the casing through a soft blemish.
The male that controls the blemish will be guaranteed a visit
from a female sooner or later there is no room for a rival.
These two males could just fight it out
but the bigger one would win.
So why not just take each other's measure
decide who's bigger
who would lose and avoid the intervening violence?
This dispute is settled and no-one gets hurt.
Real males in the insect world do resort to combat
and evolve nasty weapons just for fighting duels.
Outside a temple in Thailand deer horn stag beetles clash head on
for the honour of claiming a female
but the fight isn't just a brawl
it's a ritual every bit as formal as anything inside a temple.
There are rules to follow
The first to destroy the component is the winner
This fight is a female
and she gets to mate with the champion.
Females never have time for losers.
For most insects choosing the strongest male
and laying vast numbers of eggs is enough to win the game of survival
but some are much more inventive than that.
To an insect
even a computer is just somewhere warm and safe a carpet beetles grub
or woolly bear lives a peaceful life feeding on dust particles
but there is something else here as well.
This wasp has plans for the woolly bear.
It can run but it cant hide.
The wasp stings the woolly bear not to kill it but to stun it.
Once its paralysed she drags her still living trophy to a safe hideaway.
This wasp is a more caring mother than most insects
she lays one egg on the helpless body and leaves it to hatch.
Wasps have turned exploitation into a fine art
they nourish their young at someone else's expense.
This hawk moth caterpillar doesn't know it yet
but its about to become a walking incubator.
The females wasp hijacks the caterpillar resistance is useless
as soon as she finds somewhere soft enough
she will inject her precious eggs.
The inside of the caterpillar is mostly liquid
so her eggs will be cushioned and safe from the outside world.
She can leave them the caterpillar will take care of them from now on.
It gorges itself
trying to stockpile food reserves
for the time when it becomes a moth
but the wasp eggs have hatched into grubs
and they absorb all the nourishment the caterpillar can provide.
As fast as the caterpillar lays down fat
around its gut the wasp grubs devour it.
From then they take control they release a chemical
that imitates one of the caterpillars own hormones one that stops it
from beginning its transformation into a moth.
Instead, it keeps on eating and growing until it turns into a supergiant
a huge eating machine that just manages to keep up
with the ravenous appetites of the parasite inside.
Eventually when they've taken all they need
from the caterpillar they release chemicals to paralyse it
and they wriggle through the body wall.
Their first task in the outside world
is to spin their silken cocoons to begin their transformations into wasps.
The caterpillar will never complete its own transformation
but from one caterpillar's body hundreds of wasps have been given life.
Insects may be small and each individual seems vulnerable on its own
but they have one thing going for them.
Numbers Sheer quantity.
There are simply so many insects.
As each insect's purpose in life is to produce even more
whatever happens to the rest of the world
insects are here to stay.
There will always be lots of insects making more insects
making more insects...