Original subtitles

A tropical hill forest in East Africa.

A place where animal communities co-exist.

A natural balance between predators and prey.

It's always been this way.

But in this part of the forest, things are about to change.

An extraordinary predator is moving in...

..one that will ravage this forest,

probably the most formidable killer on Earth.

It's not an individual, but an entire army -

an army of ants.

This elite fighting force is a super-organism.

20 million sisters and a few males, acting as one -

the largest single family on the planet.

The head of the family is a new queen.

She'll produce the next generation

and the army must keep her offspring alive.

They must hunt successfully or the colony cannot grow.

Our story is set in a parallel world to our own,

a place where miniature monsters roam,

violence is the law and the most numerous and powerful survive.

This is the bug-eats-bug world of the dreaded siafu,

the African driver ant.

Driver ants don't have a permanent home. They're nomads.

Every 23 days or so, they move from one part of the forest to another,

and now they're here, somewhere,

exploring new hunting grounds and searching for a temporary home.

The neighbours from hell.

Yet despite their huge numbers, you'd hardly notice they were here at all.

They shun the light, operating down there,

mainly amongst the dead leaves on the forest floor.

They're swarm raiders, spreading through the forest,

searching relentlessly for anything that moves.

A super-predator with the mother of all appetites.

By hunting in such an enormous group,

the ants can bring down creatures much larger than themselves.

When one ant finds prey, she releases a chemical alarm signal

and within seconds hundreds of ants join the attack.

They vary considerably in size.

The largest is a soldier, half an inch long,

and, like all the workers, she has no eyes.

She's totally blind.

She finds her way about using her two antennae,

each covered in millions of hairs and sensory pits

alive to smells, vibrations and touch.

Her brain is minute. Instead, the large head is packed with muscles

that move her gigantic, razor-sharp jaws.

Her job is to protect the colony, for even driver ants have enemies.

And when heavy duty cutting is required,

her powerful jaws can slice through a victim's skin

like a knife through butter.

Most of the attacking and butchering is the job of the medium worker.

She's about half the size of a soldier, also blind,

and equipped with smaller, but tooth-studded, jaws.

Between them, soldiers and medium workers

can bring down almost anything,

including creatures as large and powerful as a grasshopper.

They rely on overwhelming numbers and sheer persistence

to capture their prey.

They also provide most of the transport.

Skittering about their feet is one of the smaller workers.

Blind like the others and just an eighth of an inch long,

she's a general helper,

who can do any job, from butchering, to building, to cleaning.

All three types co-operate to carry,

push or pull their prey along the supply lines

from the swarm's raiding front to their next home.

Day one in the new territory and the advance party has had some success.

The ant army, like any army, marches on its stomach

and the first provisions are being stashed away,

ready for the arrival of the rest of the colony.

Already, the first wave of workers is moving into the forest.

They follow chemical trails that last for about a day,

laid down by the ants ahead of them.

Their new home is in a hollow at the base of a fallen tree.

But the property is still only a building site.

Construction workers enlarge the area,

while ground workers shift debris from the main chamber.

These tiny creatures are strong.

Each is carrying a load that, in human terms,

would be more than enough for an Olympic weightlifter.

Together, they'll shift up to 80lb of soil in a couple of days.

And they'll have to work fast,

for the main colony is beginning to trickle in from the old nest site.

When they enter the new chamber, some of the workers link together,

to form long garlands of ants that join floor to ceiling.

They start to form a protective bivouac,

shaped like a large, round basket, inside the nest hollow.

And the whole structure will be made entirely of living ants.

All they are waiting for now is enough workers to fill the gaps.

Between the old nest and the new,

road gangs prepare the route on which the rest of the colony will trek.

They excavate...

..build embankments...

..and dig tunnels, always trying to keep themselves hidden from view.

They clear the highway of large pieces of soil

that might slow down the traffic. And a hungry workforce must eat.

Due to their enormous jaws, the larger ones can't feed themselves,

so smaller ants spoon-feed them.

But first, they must catch the food.

The advance party has uncovered earthworms under the leaf litter.

The ants search for weak points between segments,

their feelers constantly tasting and touching.

When they've found the right spot,

their jaws close with the equivalent force of a car-crushing machine,

and one worm becomes two.

It's being divided into handy chunks and then hauled back to camp.

All the meat is fast-tracked to the kitchen orderlies, deep in the nest.

Here it's chopped, chewed and distributed to the other ants.

And while the advance party ensures the larder is full,

the rest of the huge family prepares to leave the old nest site.

JUNGLE BIRDSONG

It's day two and the mass evacuation is underway.

The ants march along well-worn tracks,

originally foraging trails between the old nest and swarm front,

but now the main roads along which queen and colony will pass.

Their trek is about the length of two football pitches laid end to end.

They're not travelling empty-handed.

Each ant carries a larva or a pupa hung below her body -

the equivalent of us running a marathon carrying a sack of potatoes

and not stopping for a rest.

The entire emigration can take up to three days.

It seems chaotic, but every ant in this extraordinary melee

knows exactly what she's doing.

Giant soldiers, with their massive jaws, line the route,

so workers with their precious cargo travel safely along a living avenue.

They're passing at a rate of 250,000 ants an hour.

Some unwittingly carry infiltrators -

even tiny ants are host to even tinier mites.

The invading army is building in numbers.

Travelling with her subjects is the queen.

At two inches long, she is the largest ant in the world.

And she's a new queen.

When her mother's colony grew too large and divided,

half the workers switched their allegiance and now accompany her

on her first emigration.

Her enormous bulk has been coaxed along the trail

and now she takes her place at the heart of the nest.

The queen is in her palace - and what a palace it's become.

It's a living bivouac,

a nest made entirely of ants.

All its internal walls are made of ants, all its corridors

and chambers constructed of living bricks.

And when they're all assembled in their new stronghold,

they form one of the largest concentrations of ants on Earth.

Protected by these living walls are the nurseries,

where wave after wave of brood carriers deliver their load.

By the end of day three, they're packed with larvae and pupae.

In the royal chamber, the queen has yet to restart her normal duties.

Before her journey, she stopped egg production, in order to slim down

and make travelling easier.

Now, like a virgin queen,

she produces a special scent that attracts winged male ants

who fly in from other nests.

The male is also enormous, on a similar scale to the queen.

The scents she produces are irresistible.

Just a few molecules will grab a male's attention.

He searches for a way into the nest.

But a guard patrol has found him

and at first the other ants see him as food. He's in mortal danger.

The army smothers him as if he were prey,

but their intentions falter.

He produces scents to demonstrate his fitness to be consort.

If he passes muster, he'll be accepted. If he doesn't,

he'll be for the chop.

They try to clip his wings so he'll fit through the nest entrance,

but he cooperates - using spikes at the end of his abdomen,

he pulls one off himself.

Nothing is wasted. Even a wing has some nutritional value.

The rest of the workers take him into the nest.

He has their support, at least for the time being.

He's on probation.

Until he actually mates with the queen, he could still be attacked.

Another wing is removed.

He'll soon be presentable for his audience with the queen.

It's day five in the new territory.

There's no nuptial flight.

Instead, the queen's new consort is guided directly to the royal chamber.

He's not the first consort to the queen and probably won't be the last.

Driver ant queens are, for ants, unusually promiscuous.

He'll be one of many suitors she'll entertain during her lifetime.

His job done, he retires from the royal chamber and dies.

A short but productive life,

for he'll father several million new ants with hungry mouths.

The pressure is building for the colony to provide more and more food.

The raiders head west

and they don't stay on the ground.

There's plenty to eat up here in the trees.

A male hornbill cements his family into a hole in the trunk,

leaving a small gap through which he passes food.

It'll keep out tree snakes, but not ants.

Driver ants would strip the flesh from the female hornbill and chicks

in a matter of hours. He's understandably nervous.

The ants are as adept at climbing as they are at running.

As long as the forest is dark and humid,

they seem as at home in the trees as on the ground.

The army is close.

But not close enough.

If the ants climb too high and are too spread out,

there'll be too few to overwhelm prey.

This nest is out of reach.

The family is safe.

But there's plenty more prey up here.

Slugs are fair game for driver ants.

They don't run away.

The first ant makes contact.

And then another.

Others come running.

The slug tries to sit out the attack.

There are so many ants.

The victim uses the only escape route left to it.

The ants fall too.

They often use this unconventional way to get down from the trees.

But the unfortunate slug has fallen from the frying pan into the fire.

An awful lot of ants are milling about down here.

They smother their prey.

But the slug has a trick up its sleeve.

It may be slow, but it's well protected.

Its entire body is covered in a thick and noxious slime.

It's so glutinous that once their jaws are in

they can't get them out.

Other ants seem to give a helping hand.

But this one is firmly stuck.

Try as she might, she just can't get away.

For some, it's not just their jaws that are trapped.

She's almost free.

Then something remarkable happens.

Some of the workers begin to bring particles of soil

and place them on the slug. In this way,

the slime is soaked up like ink on blotting paper.

Gradually, the slug disappears under a writhing mass of earth and ants.

With its protective coat neutralised, the ants attack the slug underneath.

Slowly, the victim is sliced up.

Piece by piece, small chunks are pulled away.

As the flesh is removed,

the butchers switch roles and become transporters.

They carry the food along the foraging trails back to camp.

The larvae will be fed tonight.

By day ten, the queen resumes her primary role as super-mother,

the ultimate egg-laying machine.

Food is served to her at one end...

and eggs appear at the other.

She produces a staggering two million eggs a month.

The palace staff bustles around her,

collecting packages of eggs, grooming her constantly.

She's the colony's most valuable asset, a link to the future.

The ants around her are quite prepared to die for her,

not because of any love for a mother, but to protect the blueprint

that makes them what they are and what they do.

They pick up clumps of the precious eggs

and gently carry them to the nursery.

The already huge ant population is increasing exponentially

and the demand for food is growing astronomically.

There's a need for a greater than ever increase in rations.

Having raided to the north and west

and eliminated every living thing that slithers or crawls,

the columns head south.

The raid takes them into a wet and swampy area.

This is no deterrent.

Driver ants are proficient at crossing difficult terrain.

But a river is something even they can't manage.

They've reached the southern edge of their territory

and water and ants don't mix.

They head back inland and straight into another barrier.

But a shallow pond is no obstacle.

In order to cross, the ants simply build a bridge.

It's made out of leaves and the ants themselves -

a living bridge.

The swarm raiders stream across the pond, but the raid is failing.

They're carrying little food.

The ants retreat.

But fortunes change.

The raiding party has flushed out what seems an unassailable quarry.

Freshwater crabs are common in the forest

but a surprising targets for ants.

At first, the raiders do what's natural,

swarming over their intended victim. But there's no way their tiny jaws

will pierce the crab's thick outer skeleton.

Instinctively, they probe for its weak points.

One group examines the legs and claws for a way in.

This has its dangers.

They search for the vulnerable joints and hack their way into the leg.

Using knife-like mandibles,

they slice away the soft tissue

and as the joint is ripped and the tear widened,

the smaller workers are able to climb into the crab's legs

to reach the muscles inside.

Another group checks out the mouth.

They seem to work together.

The larger soldiers prise open the mouth parts so smaller workers can

squeeze through and attack the softer tissues behind.

The ants are dwarfed by the crab,

yet with so many attacking at one time, even a fully armoured crab

doesn't stand a chance.

Ants eat from inside out.

By day 22,

raiding parties have quartered almost every part of their territory

and in the brood chambers there are now four million more mouths to feed.

The larvae are voracious

and the raiders barely keep pace with their demand for food.

The family is at crisis point.

There's just one part of the forest left to explore

and here they stumble upon an unexpected prize,

a mound made by forest termites.

Termites have a permanent home, more a fortress than a nest.

Inside live two million residents.

Now winged termites are leaving the safety of the mound.

They're the future kings and queens

and they do go on a nuptial flight.

Late in the day, they emerge from the nest.

Just a few fail to fly very far.

They'll be easy pickings.

The reign of this young pretender will be cut short, as will its life.

The ants swarm over any termite that falls short.

The work detail

tries to control and snip off the unmanageable wings.

For a tiny ant, it's like wrestling with a gigantic sail.

Others anchor down their victim by holding onto its legs.

As the hauliers keep pulling and pushing, the butchers keep slicing.

The raiding party heads home with an almost headless victim,

but their haul of a few termites

is far less than the colony needs.

As the evening draws in and the temperature drops,

the ants become lethargic.

They head back to their nest for the night,

but in returning home they miss out on the biggest feast there's been

in this part of the forest for a long time.

The main exodus of winged termites is this night.

Tens of thousands emerge at the same time.

This would be such a glut of ant food

it would satisfy all 20 million for several days.

But the ants are not here.

The termites are on the wing. The feast is flying away.

And the ant brood is demanding increasingly more food.

If none is forthcoming, the new generation could be put on hold.

The next 24 hours are critical.

A new day

and for the ants a renewed challenge.

This has been their home for 23 days.

Successful hunting means their forest larder is almost bare.

The entire army is mobilising.

The raiding parties head out to the last place they'd found food,

where they had pinned down the few winged termites.

The bearing they've taken

is leading them straight towards the termite mound itself.

Ants and termites have been adversaries

for over 100 million years.

Now their armies of today are on a collision course.

But without any physical contact,

the blind army is as unaware of the termites ahead

as the termites are of the approaching ants.

They begin to swarm over the outside of the termite towers

that for the moment appear to them to be just mounds of dried mud.

Guards are posted

while others explore every crevice for any sign of food.

First contact.

The ants know there's something here

and change direction towards the alarm signal. They mass around,

the guards alert for any unpleasant surprises.

This is unknown territory.

Anything could be lying in wait down there.

A worker gingerly explores the gaping hole

and a scouting party lays a scent trail for others to follow.

Activity increases.

An assault is on.

Other ants have found the termites' foraging tunnels and scramble inside.

The tunnels are narrow and not like the open spaces driver ants prefer.

Termite soldiers with enormous jaws and heads

prepare to check the incursion.

A soldier termite confronts the invaders with a threat display,

but it's not going to impress a driver ant.

The ants penetrate deep into the nest

and the residents intensify their warning.

First blood is to the termites.

But the tunnel guards are in danger of being overrun.

The ants break through the first line of defence.

Another wave of ants advances unchallenged.

But the attack is not going to plan.

In the tunnels, the ants become embroiled in one-to-one duels.

The jaw-to-jaw combat is at stalemate.

Ants and termites seem locked in a lethal embrace.

The adversaries are well matched.

The ants are pulling out.

Their army will have to look elsewhere.

But not all are going home.

Those who can move out do so.

The termite mound has defeated them.

They must find food in another part of the forest.

For the ant army, a big change is inevitable.

The queen makes ready for a journey.

The lower ranks gather up all the larvae in the nursery

and move them to the nest entrance.

They've depleted the food supply in the vicinity of their nest

and must leave.

They've outstayed their welcome.

Swarm raiding parties have located a concentration of food

200 metres further on,

so the entire colony must relocate in order to exploit it.

They've wreaked havoc here,

so they're moving on to terrorise another part of the forest.

Yet the ants are important to the forest's well-being.

The culling of bugs and slugs

ensures that no one species dominates.

Driver ants help maintain the huge range of plants and animals.

Despite all the killing, driver ants are an essential part of forest life,

in many ways the good guys after all.