Leafcutter ants cleaning the refuse out of their nest.
Every single one of these tiny creatures knows where it's going
and what it's got to do when it gets there.
And furthermore, there are about 10 million more of them
in this huge underground nest beneath me.
They're all members of one highly organised society.
But they're not the blindly mechanical robotic slaves that we once thought they were.
Indeed, we now know that every insect society
is full of conflict, power struggles and mutinies.
Social insects construct the tallest of all non-human buildings.
Like these huge termite hills here in Australia.
They protect their colonies with great ferocity.
They increase the size of their societies at an alarming rate.
And they're capable of mobilising huge armies to make wars on their neighbours.
But how did these great communities develop?
Most insects, like this little sand wasp here in the deserts of Arizona,
live solitary lives.
This one has just dug a hole in which she is going to lay her eggs.
But then she does something else.
She will cater for her as yet unhatched young
by putting a caterpillar inside that hole on which they can feed.
And that is a very important stage in the development of the social life.
In fact, it's the very basis on which all the great insect societies are built.
This species of wasp, however, is still at the stage of working alone.
After stocking each nest with a caterpillar, she blocks the entrance to deter thieves.
Her burrow may be several centimetres deep.
At the bottom, lies the paralysed caterpillar.
And on its back there is now a wasp grub feeding on it.
The female wasp makes several of these nests a few feet apart
and stocks each of them with living food for her young.
Can there be a more hardworking mother?
Despite all her attempts at parental care,
the vast majority of her young will not survive.
She's too busy hunting for more caterpillars
to be able to guard all her nest sites.
Back in the distant evolutionary past,
other wasps started to build their nests alongside one another.
And here on the coast of Panama, paper wasps still do so.
Grouping their cells together
means that even though you have to leave your eggs to collect food,
there will always be someone around on guard.
The wasps are all sisters.
But, as often happens, one tends to dominate the rest.
She starts to bite her sisters with great brutality.
She is the boss, the queen.
The others may build cells, but only she will lay eggs in them.
Many of the genes in these eggs are the same as those carried by her sisters,
and the sisters look after the eggs as if they were their own.
And now, because the nest is so well-guarded, the family rears more young
than if each female were to nest alone.
So, as each egg is laid, the sisters take steps to protect it.
To do that, they need building material.
They chew wood into pulp
and then use it to build a protective wall around each egg, a cell.
So a colonial nest begins to grow.
With more and more young females needing to be fed,
the adults go hunting.
Each returning wasp bringing prey is greeted by the other workers.
They squabble over food. The queen takes the lion's share.
Those of her sisters and daughters who are high up on the social scale
also get big helpings because they bully the junior females.
In fact, the food isn't eaten by the adult who wins it.
She feeds it to her developing younger sisters.
This grouping, an enormous single sex family,
was the first step towards the development of insect societies
containing millions of individuals, and it's still their basic structure.
The forests in which the first wasps hunted
were dominated by horsetails and conifers.
They relied upon the wind to distribute their pollen.
But then about 100 million years ago,
a new kind of plant appeared which recruited insects to do the job.
And they did it with nectar-loaded flowers.
Some of these recruits then abandoned hunting and concentrated instead on this new food.
They became bees.
Today, there are about 20,000 different species of them.
This queen bumblebee mated at the end of last summer
before she hibernated.
But now she's gone off to look for a new home
because she's ready, at last, to lay those eggs.
She may take some time to find just the right place.
A deserted mouse hole.
Ideal.
First, she makes a little wax pot in which she lays a group of fertilised eggs.
In due time, these hatch into young females.
The queen now has her subjects. A colony has been established.
From now on, she does little building herself.
Her daughters take on that job
and they use a material that no wasp ever had.
It oozes from between their body segments.
It's wax.
The queen also produces a chemical substance that permeates the nest
and keeps her daughters' sexuality in check.
Their job is not to produce eggs, but to look after their younger sisters.
More and more young workers are hauling themselves out of their cells.
They don't have to travel far to find their first adult meal.
In fact, to begin with, they stay inside the nest helping with nest duties,
feeding the young, keeping the place clean, building more cells.
After a few days, they begin to venture outside the nest to help in collecting food.
If the colony is to be properly nourished, they must gather not only nectar, but pollen.
Nectar, they transport in their crops
but pollen is held in a tiny ball by a brush of stiff hairs on their two hind legs.
A worker can carry a lump weighing half as much as she does herself.
Each bundle is carefully unloaded into one of the storage cells.
The pollen isn't eaten by workers.
They unselfishly bring it back for the larvae,
for it's rich in protein and essential food for their development.
By the late summer, there may be more than 200 workers in the nest.
Although the colony is now close to its maximum size,
the queen is still laying.
But these batches of eggs are different.
She's now stopped producing the chemical substance
that repressed the sexual development of her daughters,
so these eggs will develop into new queens.
The change affects not just her eggs but her existing daughters, the workers.
No longer restrained by the queers chemical control,
some workers have started laying their own eggs.
This doesn't suit the queen and she destroys them.
The workers haven't mated,
but their eggs can develop nonetheless, and become males.
The queen eats as many of these eggs as she can find
because as well as queen eggs, she's also producing male eggs
and can't tolerate the competition.
She keeps such a close watch
that she manages to destroy the workers' eggs almost as soon as they're laid.
The end of summer approaches.
There's now anarchy in the colony. The social order has collapsed.
Many of the workers whose eggs are being destroyed by the queen
start to attack her.
The onslaught is brutal. No quarter is given.
Eventually, they sting her to death.
The end of the colony has come.
None of the workers will survive the winter...
but the young queens will have left the nest and found males.
It's they who will establish new colonies next spring.
Bumblebees have a particular problem.
In any given area,
there's only a limited number of holes that are suitable for nests.
European honeybees, which in the wild, nest in holes in trees,
have similar difficulty.
But some bees have adopted a very radical solution.
A very brave solution to that difficulty.
They nest out in the open but at the top of tall trees.
Sometimes very tall trees.
These are the giant Asiatic bees, the biggest of all honeybees.
They are found from the Himalayas all the way down to Southeast Asia.
These colonies are in Malaysia.
They defend themselves with stings. Very, very powerful stings,
which is why I have to wear a bee suit.
And it's not just against one bee that you have to guard yourself.
Because if one bee attacks you, it releases a pheromone,
a chemical signal, which is detected by the others in the comb,
and within seconds there will be hundreds,
indeed probably thousands, of them all around you
launching a mass attack and stinging you.
And some of those stings can actually go through a bee suit.
So, something to be avoided.
Stinging is a very expensive form of defence
because when a bee loses its sting, it dies.
So it's better for the colony to warn predators off before they have to fight them off.
And they warn them with some dramatic displays.
I've got a reproduction of a hornet, which is one of the main enemies of bees.
I'll see if I can get them to do it.
Just watch. There.
See, there's a moving wave which passes over the surface of the colony.
And that not only produces an impressive pattern,
but it also makes it very difficult for any aggressor,
like perhaps a hornet which eats bees,
to actually land on that moving carpet of wings.
The colony's great treasure, of course, is its huge store of honey.
This is produced from nectar which the bees industriously collect from flowers.
They systematically expose it to the air so that the water it contains evaporates
and the nectar becomes sweeter and thicker.
Eventually it turns into honey.
The combs in which they store it are continuously guarded by the covering of bees.
They cling so thickly that it might seem that nothing could get past them.
But some thieves know how to do so, particularly at night.
A death's-head hawk moth flies over the surface of the colony
and goes so close to it
that the bees are alarmed enough to wave their warning.
But the moth is not put off. It wants honey.
Amazingly, it manages to land on the carpet of bees
and quickly pushes its way through them.
A quick sip of honey and it's off.
It succeeds because, although it looks nothing like a bee to our eyes,
it has camouflaged itself with a smell,
a pheromone that convinces the bees that it's one of them.
But in spite of such raids,
bees, thanks to their stings, retain their precious honey.
Precious because it is that that enables them to survive a season without flowers.
While some descendants of the wasps became flower-foraging bees,
others remained hunters but went down to the ground to search for their prey.
There, wings were more of a hindrance than a help
and these insects lost their wings for most of their lives.
They're the ants.
These are wood ants
and they build nests even bigger than those of the giant bees.
This one is in the pine forests of the Alps.
Hunting parties go out from the nest along well-established trails to search for prey.
Anything their own size is quickly overpowered.
But by working together,
wood ants can tackle prey much bigger than themselves.
Some caterpillars are covered with stinging hairs but the ants cut these off one by one.
And they can slice right through a beetle's hard armour.
Now they are attacking another hunter, a spider.
Everything they catch is taken back to the colony
to be shared by those workers that stayed at home, looking after the young.
The disadvantage of building a huge nest like this
is that you're very obvious to predators.
But these ants have a very effective way of defending themselves. Watch.
Hm!
The unmistakable acrid smell of formic acid.
Most ants, like their wasp ancestors, have stings.
But not these wood ants.
Instead of injecting poison, they squirt it, and very accurately, too.
They don't eat just meat.
They also visit aphids that sit in the branches above,
drinking the pine tree's sap.
This contains more sugar than the aphids need, so the ants drink the excess.
And they collect it just as fast as the aphids excrete it.
They carry it back to the nest
but in this case they transport it inside their swollen stomachs.
In fact, this liquid, honeydew, makes up more than two thirds of the colony's diet.
All these wood ant nests are connected to one another by trails.
And, indeed, they're also genetically related to one another.
There are some 1,200 of them in this one patch of forest
and that makes this what is thought to be
the biggest supercolony of ants in the whole world.
By mid June, the supercolony is ready to reproduce.
Out of every nest, among the workers, come individuals with wings.
Some nests produce only males.
They take off in droves.
Other nests produce only females.
Both sexes, now that they are winged, look remarkably like wasps.
A reminder of their ancestry.
Unlike wasps, however,
these flyers are not very confident about getting into the air.
Males and females assemble in the nearby meadows.
The queens lay down chemical trails
so that the males may quickly discover exactly where they are.
And the males are quick to take the hint.
The males only live for a few days
and they mate as quickly and as frequently as they can.
A queen, on the other hand, may live for as long as 10 years
and a single mating will provide her with enough sperm to last for her entire life.
For a female, mating is often a bit of a battle.
Sometimes she has to bite a male to make him release her.
Sometimes she has to hang on to him because he's impatient and wants to move on.
The newly-mated queens gather together in the undergrowth.
Here, they shed their wings.
They've found their males so their travelling is over.
Now, each must find an existing nest in which to lay her eggs.
This one encounters a column of workers.
A wood ant nest may contain as many as 1,000 queens.
But will these workers allow her to be one of them?
If they don't, they will bite her to death.
She's been accepted.
The workers have detected chemical clues on her body
that tells them that she is originally from one of the nests in their supercolony.
She's large and fat. Walking is not easy for her.
A single worker carries her along the trail back home.
Perhaps even to the same nest in which she started life.
Ants live almost everywhere.
The water falling in this mangrove swamp in Australia
exposes in the wet mud an ant's nest.
Every time the tide recedes,
the ants must repair any damage the water may have caused.
Collapsed entrances must be reopened and blocked tunnels cleared.
Now that the mud flats are exposed,
the ants hurry to collect what food the tide might have delivered.
But there are still some stretches of water to be crossed.
The surface tension of the water supports them as they dance across it.
Sometimes they actually swim.
And there has indeed been a new delivery of food.
But the tide has also created a problem.
It has washed away the chemical trails that mark the frontiers of their territory,
so there's now no clear boundary between them
and ants belonging to a neighbouring colony.
The interrogation of a stranger is complex and detailed.
Who are you? Where do you come from?
Answers are readily given and accepted.
But every now and then, they have to fight to settle the question.
They may have sorted out their disagreement but now there is a bigger threat to both of them.
The tide is turning again.
They must get back to the safety of their nests.
While the tide has been out,
larvae and pupae have been moved around the nest
to keep them at the temperature needed for their proper development.
Now, they must be moved again for the nest is not watertight.
Many of the tunnels and chambers are flooded with every tide.
There's no time to waste.
But the water doesn't reach every part of the nest,
for the ants have constructed bell-shaped chambers
that trap pockets of air and so create refuges
where the adults and the young can sit out the high tide.
Here in Arizona, the problem for an ant
is not too much water, but too little.
The rainfall is so low
that there's hardly any vegetation and very little to eat,
so an ant has to be prepared to eat whatever it can find.
There are seeds, but seeds are very tough
and you need very powerful jaws to crack them.
But then, that's exactly what these harvester ants have got.
They make an intensive search of the sand.
Almost any seed will be collected.
Food around here is very scarce. They can't afford to be fussy.
They carry their gleanings back to the nest to store it in larders,
many of which are several metres below ground.
But, like the mangrove ants, they must work fast.
The desert warms quickly and before long the heat will be intolerable.
By nightfall, the harvesters are back inside the nest.
But there's still a lot going on out in the desert.
There's another ant here, too. The night ant.
This is one of their nests in front of me.
They normally only come out after dark and they're generalists.
They'll eat pretty well anything.
But they have a particular taste for seeds.
The trouble is that the harvester ants
will have gathered all the seeds during the day
unless the night ants can do something about it.
Just after dark,
the night ants start a major spoiling operation against their rivals.
They start to shift stones and fragments of plants
to block up some holes near their nest.
By morning, it's clear what they've done.
They've trapped the harvesters inside their own nests.
The harvesters now have a lot of work to do
before they can get out to collect more seeds.
They clear away the rubble as quickly as they can.
But this takes time.
If they are seriously delayed, the day will be too hot
for them to spend time out in the open.
So today, they can't collect as much as they normally do.
And that means that by nightfall,
there will still be seeds on the ground for the night ants to collect.
Not all ants live in permanent nests.
In the tropical forests of Africa and South America,
there are some that are nomads.
These army ants in the rain forests of Central America
are camped in the base of a tree.
They've been there for three weeks.
During this time the queen has been laying eggs, several thousand a day.
The army has also been ransacking the surrounding forest for prey.
But now it's time for them to find new hunting grounds.
So once more, they start to march.
The site for the new bivouac
has not been picked by the queen, but by the workers.
Scouts have been exploring the neighbourhood and they've decided on a new place.
And now their chemical trails are leading the whole colony
from the old bivouac to the new one.
As in an army, the soldiers are prepared to risk their lives for the common good.
A group of them interlock their bodies to form a safety barrier
that will catch any of their companions that might slip off this sloping trunk.
They take everything with them.
Larvae, food, and in this case and very rarely seen, winged males.
By the time daylight comes, the army has established a new bivouac.
Its walls and tunnels
are formed by the interlinked bodies of hundreds and thousands of individuals.
But this is only a temporary camp.
They still haven't reached fresh hunting grounds.
Even so, they must eat and the workers set off to find food.
There are probably a million individual ants in this one colony
and together, they are collaborating and cooperating
so that the colony has become one great superorganism.
There's no central controlling intelligence as such.
Instead, the behaviour of the superorganism is the cumulative result
of thousands upon thousands of tiny mini-decisions by individual ants.
A worker moves forward into new territory leaving a chemical trail behind it
and then another, following in its trail, advances still a little further.
So, the superorganism as a whole
is moving through the forest, searching for food.
These hunters can subdue almost any other creature in the undergrowth.
Some predators may be armed with virulent poisons
but their attackers are too small to sting.
A lizard has no defence at all.
A special caste of workers with particularly large jaws
protect the smaller workers as they sting their prey and butcher it.
The venom in their stings liquefies the tissues of their victims
so that the bodies are more easily cut up into smaller pieces for transport.
The chemical trails laid down by the first scouts
have now been strengthened and broadened by the passage of many, many more workers.
And now those trails are serving as highways
along which booty is being brought back to the bivouac to feed the young brood.
Remarkably, almost as soon as these workers return with food,
scouts begin to search for a new bivouac site.
The colony will move again tonight, and every night for the next few weeks
until the queen is ready to lay more eggs.
When it comes to creating a permanent home for the colony,
the champions by far are these tiny creatures.
Termites.
Unlike ants, all termites are vegetarians.
They are in fact descended not from wasps, but from cockroaches.
And their huge nests act not only as their fortresses
but their food stores.
They build with nothing but mud and their own excrement
yet their nests are gigantic.
If termites were our size,
some of their homes would be four times as tall as New York's skyscrapers
and measure up to five miles across at their base.
These are not quite so tall
but they are particularly remarkable for another reason.
Every one of these termite hills points in the same direction,
north and south.
It's as though they were needles in a compass.
And, indeed, they're called magnetic termites.
They in fact take their cue for building
from the magnetism of the earth.
But the benefit of doing so comes not from that,
but from the daily movement of the sun.
In the morning, the rays of the rising sun
strike the eastern face of the mound foursquare.
And the termites, after the cold of the night, need warming up
and are gathered in galleries immediately below the surface.
But as the day continues, it warms up, but the termites don't overheat
because the rays of the sun only strike the surface glancingly.
And by midday,
the full force of the sun is felt only on the top edge.
As the sun moves towards the west,
so this face becomes roastingly hot.
But the eastern face falls into shadow
and remains relatively cool
and the termites stay at the temperature that suits them best.
Other termites escape the heat of the day
by retreating to deep cellars below their mounds.
But these magnetic termites colonise areas that flood during the rainy season
and the ground beneath them is regularly waterlogged.
So their compass-like mounds
are a response not just to the movement of the sun,
but to badly drained sites.
Here in South Africa, it can also get very hot
but there's no danger of flooding
so termites can take refuge from the heat below ground
where it's cool and relatively stable.
But two million insects living below ground
create a different kind of problem.
The air around them gets stale.
So termites need to have a way of linking the underground air
with the fresh air above, a ventilation system.
And they do that with this.
And to see how it works, you've got to look inside.
Using the latest scanning techniques,
we can create a picture of the mound's interior.
An intricate network of passages lead to a central chimney.
Hot, stale air from the insect population below
rises up through the chimney.
But the top of the mound is sealed.
So how does this stale air escape?
The mound may look as though it has strong defensive walls like a fortress.
But in fact these walls are porous.
And their primary purpose is to harness the wind.
Fresh air blowing against the side of the mound
is forced through the tiny holes in these walls.
From there, it travels through the smaller tunnels
until it reaches the central chimney.
Here, the cooler, fresh air mixes with the hot, stale air
rising from the insect community below.
Meanwhile, some air is blown around the side of the mound.
This creates a suction that pulls the stale air out of the chimney
and out through the outer walls.
So an internal air current is created and the whole mound ventilated.
The mound's inhabitants spend most of their time close to or below ground level.
Beneath their living quarters, there are garden chambers
where the termites cultivate a fungus that rots the wood and vegetation they collect
and make it digestible.
Farther down still, the queen lies in her own chamber.
Her huge body is a gigantic egg-producing factory.
She's so swollen that she can't look after herself.
The workers must constantly clean her
and feed her with food from their own crops.
Her partner, with whom she founded the colony maybe 20 years ago,
is still with her and mates with her throughout her life.
She lays eggs at an extraordinary rate,
as many as 30,000 a day.
As she produces them, so workers remove them from the royal chamber
and take them to nurseries.
There they'll be fed on compost from the fungus gardens until they turn into adults.
The superorganism that lives in this great castle
crops the surrounding vegetation just about as severely as an antelope.
The density of individual termites around here is extraordinary.
Over 100,000 per square metre.
And just as there are lions and leopard that hunt antelope,
so in the undergrowth, there are insect hunters
which prey on the tiny herbivores.
The ants, the termites' ancient enemy.
Matabele ants, specialist termite hunters.
A scout has laid down a clear chemical trail
and this battalion of workers have picked it up and are following it.
There may be only a few hundred of them
but they are going to severely test the defences of a termite colony.
The mound has formidable guards, soldier termites.
The ants have a special technique for dealing with these soldiers.
They grab the termite's jaw
and then sting it in the only vulnerable place on its head,
in its mouth.
The ants' front line breaks into the colony.
Reinforcements for the termite soldiers arrive quickly.
Already there are casualties on both sides.
But the invaders overwhelm the defenders.
It's not to the ants' advantage to kill an entire termite colony
any more than it would be sensible for farmers to exterminate their cattle.
Better to let most survive so that they can be regularly raided.
So, although there are millions of termites in the colony,
the Matabele ants rarely go deep into the nest to press home their victory.
The raid lasts less than 15 minutes.
Nonetheless, the spoils are impressive.
Termite bodies are now being piled in dumps outside the nest.
Many of the casualties are still alive but paralysed by the ants' stings.
Now the raiders have the considerable task
of carrying their victims back to their nest.
They will have to take all their booty with them.
If any termite bodies are left behind, they will be collected by scavengers.
The termite soldiers certainly fought hard.
One of their dead still grips a Matabele soldier in its jaws,
which it killed before it was itself slaughtered.
Well, it's been a successful raid.
Many of the bigger ones have got mouthfuls of termites.
How they manage to hold all of them in one mouthful, I don't know.
But, obviously, they've got a little way to go now
and soon the young ones back at the nest will be getting good food.
The Matabele ants will use their plunder to raise more workers.
Ironically, the raid will have the same effect on the termites.
The queen will detect the loss of her soldiers and workers
and will increase her output of eggs to repopulate the colony.
So there will be just as much food for the Matabeles the next time they raid.
The tiny creatures of the undergrowth
were the first animals of any kind to colonise the land.
They established the foundations of the land's ecosystems.
Ultimately they were able to transcend
any limitations of their small size
by banding together in huge communities of millions
and putting up buildings like this one.
If we and the rest of the backboned animals were to disappear overnight,
the rest of the world would get on pretty well.
But if they were to disappear,
the land's ecosystems would collapse.
The soil would lose its fertility.
Many of the plants would no longer be pollinated.
Lots of animals, amphibians, reptiles, birds, mammals
would have nothing to eat.
And our fields and pastures would be covered with dung and carrion.
These small creatures are within a few inches of our feet
wherever we go on land
but often, they're disregarded.
We would do very well to remember them.