Supersocieties Life in the Undergrowth


Supersocieties

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Leaf-cutter ants cleaning the refuse out of their nest.

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Every single one of these tiny creatures knows where it's going

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and what it's got to do when it gets there.

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And, furthermore, there are about ten million more of them in this huge underground nest beneath me.

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They are all members of one highly organised society.

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But they're not the blindly mechanical, robotic slaves that we once thought they were.

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Indeed, we now know that every insect society is full of conflict,

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power struggles and mutinies.

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Social insects construct the tallest of all non-human buildings.

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Like these huge termite hills here in Australia.

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They protect their colonies with great ferocity.

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They increase the size of their societies at an alarming rate.

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And they're capable of mobilising huge armies to make wars on their neighbours.

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But how did these great communities develop?

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Most insects, like this little sand wasp here in the deserts of Arizona,

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live solitary lives.

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This one has just dug a hole in which she is going to lay her eggs.

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But then she does something else.

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She will cater for her as yet unhatched young

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by putting a caterpillar inside that hole on which they can feed.

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And that is a very important stage in the development of the social life.

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In fact, it's the very basis on which all the great insect societies are built.

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This species of wasp, however, is still at the stage of working alone.

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After stocking each nest with a caterpillar,

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she blocks the entrance to deter thieves.

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Her burrow may be several centimetres deep.

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At the bottom lies the paralysed caterpillar.

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And on its back, there is now a wasp grub, feeding on it.

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The female wasp makes several of these nests a few feet apart

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and stocks each of them with living food for her young.

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Can there be a more hard-working mother?

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Despite all her attempts at parental care,

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the vast majority of her young will not survive.

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She's too busy hunting for more caterpillars

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to be able to guard all her nest sites.

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Back in the distant evolutionary past,

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other wasps started to build their nests alongside one another.

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And here on the coast of Panama, paper wasps still do so.

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Grouping their cells together means that even though you have

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to leave your eggs to collect food,

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there will always be someone around on guard.

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The wasps are all sisters.

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But, as often happens, one tends to dominate the rest.

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She starts to bite her sisters with great brutality.

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She is the boss, the queen.

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The others may build cells, but only she will lay eggs in them.

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Many of the genes in these eggs are the same as those carried by her

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sisters, and the sisters look after the eggs as if they were their own.

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And now, because the nest is so well guarded,

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the family rears more young than if each female were to nest alone.

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So as each egg is laid, the sisters take steps to protect it.

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To do that they need building material.

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They chew wood into pulp and then use it to build a protective

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wall around each egg, a cell, so a colonial nest begins to grow.

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With more and more young females needing to be fed, the adults go hunting.

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Each returning wasp bringing prey is greeted by the other workers.

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They squabble over food.

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The queen takes the lion's share.

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Those of her sisters and daughters who are high up on the social scale

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also get big helpings, because they bully the junior females.

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In fact, the food isn't eaten by the adult who wins it.

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She feeds it to her developing younger sisters.

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This grouping, an enormous single-sex family,

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was the first step towards the development of

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insect societies containing millions of individuals, and it's still their basic structure.

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The forests in which the first wasps hunted

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were dominated by horsetails and conifers.

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They relied upon the wind to distribute their pollen.

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But then, about a hundred million years ago,

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a new kind of plant appeared which recruited insects to do the job.

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And they did it with nectar-loaded flowers.

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Some of these recruits then abandoned hunting

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and concentrated instead on this new food.

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They became bees.

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Today there are about 20,000 different species of them.

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This queen bumblebee mated at the end of last summer, before she hibernated.

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But now she has gone off to look for a new home, because she's ready at last to lay those eggs.

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She may take some time to find just the right place.

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A deserted mouse hole.

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Ideal!

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First she makes a little wax pot in which she lays a group of fertilised eggs.

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In due time, these hatch into young females.

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The queen now has her subjects.

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A colony has been established.

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From now on she does little building herself.

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Her daughters take on that job

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and they use a material that no wasp ever had.

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It oozes from between their body segments. It's wax.

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The queen also produces a chemical substance

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that permeates the nest and keeps her daughters' sexuality in check.

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Their job is not to produce eggs but to look after their younger sisters.

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More and more young workers are hauling themselves out of their cells.

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They don't have to travel far to find their first adult meal.

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In fact, to begin with, they stay inside the nest,

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helping with nest duties, feeding the young, keeping the place clean, building more cells.

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After a few days, they begin to venture outside the nest,

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to help in collecting food.

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If the colony is to be properly nourished,

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they must gather not only nectar but pollen.

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Nectar they transport in their crops, but pollen is held in a tiny

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ball by a brush of stiff hairs on their two hind legs.

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A worker can carry a lump weighing half as much as she does herself.

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Each bundle is carefully unloaded into one of the storage cells.

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The pollen isn't eaten by workers.

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They unselfishly bring it back for the larvae,

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for it's rich in protein and essential food for their development.

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By the late summer, there may be more than 200 workers in the nest.

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Although the colony is now close to its maximum size,

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the queen is still laying, but these batches of eggs are different.

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She's now stopped producing the chemical substance that

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repressed the sexual development of her daughters, so these eggs will develop into new queens.

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The change affects not just her eggs but her existing daughters, the workers.

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No longer restrained by the queen's chemical control,

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some workers have started laying their own eggs.

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This doesn't suit the queen, and she destroys them.

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The workers haven't mated,

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but their eggs can develop nonetheless and become males.

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The queen eats as many of these eggs as she can find,

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because, as well as queen eggs,

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she's also producing male eggs and can't tolerate the competition.

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She keeps such a close watch that she manages to destroy the workers' eggs almost as soon as they're laid.

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The end of summer approaches.

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There's now anarchy in the colony.

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The social order has collapsed.

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Many of the workers whose eggs are being destroyed by the queen start to attack her.

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The onslaught is brutal.

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No quarter is given.

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Eventually, they sting her to death.

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The end of the colony has come.

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None of the workers will survive the winter,

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but the young queens will have left the nest and found males.

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It's they who will establish new colonies next spring.

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Bumblebees have a particular problem.

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In any given area, there is only a limited number of holes that are suitable for nests.

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European honeybees, which in the wild nest in holes in trees, have similar difficulty.

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But some bees have adopted a very radical solution, a very brave solution, to that difficulty.

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They nest out in the open,

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but at the top of tall trees, sometimes VERY tall trees.

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These are the giant Asiatic bees, the biggest of all honeybees.

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They are found from the Himalayas all the way down to southeast Asia.

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These colonies are in Malaysia.

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They defend themselves with stings, very, very powerful stings, which is why I have to wear a bee suit.

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And it's not just against one bee that you have to guard yourself,

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because if one bee attacks you, it releases a pheromone,

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a chemical signal, which is detected by the others in the comb,

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and within seconds there will be hundreds, indeed, probably thousands, of them

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all around you, launching a mass attack and stinging you.

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And some of those stings can actually go through a bee suit.

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So it's something to be avoided.

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Stinging is a very expensive form of defence,

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because when a bee loses its sting, it dies.

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So it's better for the colony to warn predators off before they have to fight them off.

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And they warn them with some dramatic displays.

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I've got a reproduction of a hornet,

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which is one of the main enemies of bees.

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I'll see if I can get them to do it.

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Just watch.

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There!

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See? There's a moving wave which passes over the surface of the colony,

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and that not only produces an impressive pattern, but it also makes it very difficult for any

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aggressor, like, perhaps, a hornet, which eats bees, to actually land on that moving carpet of wings.

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The colony's great treasure, of course, is its huge store of honey.

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This is produced from nectar, which the bees industriously collect from flowers.

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They systematically expose it to the air so that the water it contains

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evaporates and the nectar becomes sweeter and thicker.

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Eventually it turns into honey.

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The combs in which they store it are continuously guarded by the covering of bees.

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They cling so thickly that it might seem that nothing could get past them.

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But some thieves know how to do so, particularly at night.

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A death's-head hawk moth flies over the surface of

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the colony, and goes so close to it that the bees are alarmed enough to wave their warning.

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But the moth is not put off.

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It wants honey.

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Amazingly, it manages to land on the carpet of bees and quickly pushes its way through them.

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A quick sip of honey, and it's off.

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It succeeds because, although it looks nothing like a bee to our eyes,

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it has camouflaged itself with a smell, a pheromone,

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that convinces the bees that it's one of them.

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But in spite of such raids, bees, thanks to their stings, retain their precious honey, precious

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because it is that that enables them to survive a season without flowers.

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While some descendants of the wasps became flower-foraging bees, others

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remained hunters but went down to the ground to search for their prey.

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There, wings were more of a hindrance than a help,

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and these insects lost their wings for most of their lives.

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They're the ants.

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These are wood ants and they build nests even bigger than those of the giant bees.

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This one is in the pine forests of the Alps.

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Hunting parties go out from the nest along well-established trails to search for prey.

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Anything their own size is quickly overpowered.

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But by working together, wood ants can tackle prey much bigger than themselves.

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Some caterpillars are covered with stinging hairs, but the ants cut these off, one by one.

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And they can slice right through a beetle's hard armour.

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Now they are attacking another hunter, a spider.

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Everything they catch is taken back to the colony to be shared by those workers

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that stayed at home, looking after the young.

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The disadvantage of building a huge nest like this

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is that you're very obvious to predators.

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But these ants have a very effective way of defending themselves. Watch.

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Mmm, the unmistakable, acrid smell of formic acid.

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Most ants, like their wasp ancestors, have stings.

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But not these wood ants.

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Instead of injecting poison, they squirt it, and very accurately too.

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They don't eat just meat.

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They also visit aphids that sit in the branches above drinking the pine tree's sap.

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This contains more sugar than the aphids need, so the ants drink the excess.

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And they collect it just as fast as the aphids excrete it.

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They carry it back to the nest,

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but in this case they transport it inside their swollen stomachs.

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In fact, this liquid, honeydew, makes up more than two thirds of the colony's diet.

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All these wood-ant nests are connected to one another by trails.

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And indeed, they're also genetically related to one another.

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There's some 1,200 of them in this one patch of forest,

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and that makes this what is thought to be the biggest super-colony of ants in the whole world.

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By mid-June the super-colony is ready to reproduce.

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Out of every nest, among the workers, come individuals with wings.

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Some nests produce only males.

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They take off in droves.

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Other nests produce only females.

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Both sexes, now that they're winged, look remarkably like wasps,

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a reminder of their ancestry.

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Unlike wasps, however,

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these flyers are not very confident about getting into the air.

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Males and females assemble in the nearby meadows.

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The queens lay down chemical trails,

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so that the males may quickly discover exactly where they are,

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and the males are quick to take the hint.

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The males only live for a few days,

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and they mate as quickly and as frequently as they can.

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A queen, on the other hand, may live for as long as ten years,

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and a single mating will provide her with enough sperm to last for her entire life.

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For a female, mating is often a bit of a battle.

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Sometimes she has to bite a male to make him release her, sometimes

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she has to hang on to him because he's impatient and wants to move on.

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The newly mated queens gather together in the undergrowth.

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Here they shed their wings.

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They've found their males, so their travelling is over.

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Now each must find an existing nest in which to lay her eggs.

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This one encounters a column of workers.

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A wood-ant nest may contain as many as a thousand queens.

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But will these workers allow her to be one of them?

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If they don't, they will bite her to death.

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She's been accepted.

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The workers have detected chemical clues on her body that tells them

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that she's originally from one of the nests in their super-colony.

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She's large and fat.

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Walking is not easy for her.

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A single worker carries her along the trail back home,

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perhaps even to the same nest in which she started life.

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Ants live almost everywhere.

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The water falling in this mangrove swamp in Australia exposes in the wet mud...

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an ants' nest!

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Every time the tide recedes,

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the ants must repair any damage the water may have caused.

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Collapsed entrances must be re-opened

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and blocked tunnels cleared.

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Now that the mud flats are exposed,

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the ants hurry to collect what food the tide might have delivered.

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But there are still some stretches of water to be crossed.

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The surface tension of the water supports them

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as they dance across it.

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Sometimes they actually swim.

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And there has indeed been a new delivery of food.

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But the tide has also created a problem.

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It has washed away the chemical trails

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that mark the frontiers of their territory,

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so there's now no clear boundary

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between them and ants belonging to a neighbouring colony.

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The interrogation of a stranger is complex and detailed.

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Who are you? Where do you come from?

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Answers are readily given and accepted.

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But every now and then, they have to fight to settle the question.

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They may have sorted out their disagreement,

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but now there is a bigger threat to both of them.

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The tide is turning again.

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They must get back to the safety of their nests.

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While the tide has been out,

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larvae and pupae have been moved around the nest

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to keep them at the temperature needed for their proper development.

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Now they must be moved again, for the nest is not watertight.

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Many of the tunnels and chambers are flooded with every tide.

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There's no time to waste.

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But the water doesn't reach every part of the nest,

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for the ants have constructed bell-shaped chambers

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that trap pockets of air and so create refuges where the adults and the young can sit out the high tide.

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Here in Arizona,

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the problem for an ant is not too much water but too little.

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The rainfall is so low that there's hardly any vegetation and very little to eat,

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so an ant has to be prepared to eat whatever it can find.

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There are seeds, but seeds are very tough and you need very powerful jaws to crack them.

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But then, that's exactly what these harvester ants have got.

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They make an intensive search of the sand.

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Almost any seed will be collected.

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Food around here is very scarce.

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They can't afford to be fussy.

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They carry their gleanings back to the nest to store it in larders,

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many of which are several metres below ground.

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But, like the mangrove ants, they must work fast.

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The desert warms quickly and before long the heat will be intolerable.

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By nightfall, the harvesters are back inside the nest.

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But there's still a lot going on out in the desert.

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There's another ant here too, the night ant.

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This is one of their nests in front of me.

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They normally only come out after dark and they're generalists, they'll eat pretty well anything.

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But they have a particular taste for seeds.

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The trouble is that the harvester ants will have gathered all the seeds during the day,

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unless the night ants can do something about it.

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Just after dark, the night ants start a major spoiling operation against their rivals.

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They start to shift stones and fragments of plants

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to block up some holes near their nest.

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By morning, it's clear what they've done.

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They've trapped the harvesters inside their own nests.

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The harvesters now have a lot of work to do

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before they can get out to collect more seeds.

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They clear away the rubble as quickly as they can.

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But this takes time.

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If they're seriously delayed,

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the day will be too hot for them to spend time out in the open.

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So today, they can't collect as much as they normally do.

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That means that by nightfall there will still be seeds on the ground

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for the night ants to collect.

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Not all ants live in permanent nests.

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In the tropical forests of Africa and South America,

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there are some that are nomads.

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These army ants in the rainforests of central America are camped in the base of a tree.

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They've been there for three weeks.

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During this time, the queen has been laying eggs, several thousand a day.

0:31:510:31:55

The army has also been ransacking the surrounding forest for prey.

0:31:550:32:00

But now it's time for them to find new hunting grounds,

0:32:000:32:04

so once more they start to march.

0:32:040:32:06

The site for the new bivouac has not been picked by the queen but by the workers.

0:32:180:32:24

Scouts have been exploring the neighbourhood,

0:32:240:32:27

and they've decided on a new place.

0:32:270:32:29

And now their chemical trails are leading the whole colony

0:32:290:32:33

from the old bivouac to the new one.

0:32:330:32:35

As in an army,

0:32:390:32:40

the soldiers are prepared to risk their lives for the common good.

0:32:400:32:44

A group of them interlock their bodies to form a safety barrier

0:32:440:32:48

that will catch any of their companions that might slip off this sloping trunk.

0:32:480:32:53

They take everything with them -

0:32:530:32:55

larvae, food and in this case, and very rarely seen, winged males.

0:32:550:32:59

By the time daylight comes, the army has established a new bivouac.

0:33:140:33:19

Its walls and tunnels are formed by the interlinked bodies

0:33:190:33:22

of hundreds and thousands of individuals.

0:33:220:33:25

But this is only a temporary camp.

0:33:330:33:35

They still haven't reached fresh hunting grounds.

0:33:350:33:38

Even so, they must eat, and the workers set off to find food.

0:33:380:33:42

There are probably a million individual ants in this one colony,

0:34:120:34:16

and together they are collaborating and cooperating so that the colony has become one great super-organism.

0:34:160:34:22

There's no central controlling intelligence as such.

0:34:220:34:26

Instead, the behaviour of the super-organism is the cumulative result

0:34:260:34:31

of thousands upon thousands of tiny mini-decisions by individual ants.

0:34:310:34:35

A worker moves forward into new territory, leaving a chemical trail

0:34:350:34:39

behind it, and then another, following in its trail, advances still a little further.

0:34:390:34:44

So the super-organism as a whole is moving through the forest searching for food.

0:34:440:34:50

These hunters can subdue almost any other creature in the undergrowth.

0:34:560:35:01

Some predators may be armed with virulent poisons, but their attackers are too small to sting.

0:35:010:35:06

A lizard has no defence at all.

0:35:090:35:11

A special caste of workers with particularly large jaws

0:35:310:35:36

protect the smaller workers as they sting their prey and butcher it.

0:35:360:35:40

The venom in their stings liquefies the tissues of their victims so that

0:35:510:35:56

the bodies are more easily cut up into smaller pieces to transport.

0:35:560:36:00

The chemical trails laid down by the first scouts have now been

0:36:190:36:24

strengthened and broadened by the passage of many, many more workers.

0:36:240:36:28

And now those trails are serving as highways along which booty

0:36:280:36:32

is being brought back to the bivouac to feed the young brood.

0:36:320:36:37

Remarkably, almost as soon as these workers return with food,

0:36:560:37:01

scouts begin to search for a new bivouac site.

0:37:010:37:04

The colony will move again tonight and every night

0:37:050:37:09

for the next few weeks until the queen is ready to lay more eggs.

0:37:090:37:13

When it comes to creating a permanent home for the colony,

0:37:160:37:20

the champions by far are these tiny creatures, termites.

0:37:200:37:25

Unlike ants, all termites are vegetarians.

0:37:260:37:30

They are, in fact, descended not from wasps but from cockroaches,

0:37:300:37:34

and their huge nests act not only as their fortresses but their food stores.

0:37:340:37:39

They build with nothing but mud and their own excrement, yet their nests are gigantic.

0:37:410:37:46

If termites were our size, some of their homes would be

0:37:460:37:49

four times as tall as New York skyscrapers

0:37:490:37:52

and measure up to five miles across at their base.

0:37:520:37:56

These are not quite so tall, but they are particularly remarkable for another reason.

0:37:560:38:00

Every one of these termite hills points in the same direction, north and south.

0:38:030:38:09

It's as though they were needles in a compass.

0:38:090:38:13

And indeed, they are called magnetic termites.

0:38:130:38:17

They in fact take their cue for building from the magnetism of the earth, but the benefit of

0:38:170:38:25

doing so comes not from that but from the daily movement of the sun.

0:38:250:38:30

In the morning, the rays of the rising sun strike the eastern face of the mound foursquare.

0:38:410:38:49

And the termites, after the cold of the night, need warming up

0:38:490:38:52

and are gathered in galleries immediately below this surface.

0:38:520:38:57

But as the day continues, it warms up, but the termites don't overheat because the rays of the sun only

0:38:570:39:02

strike the surface glancingly

0:39:020:39:05

and by midday the full force of the sun is felt only on the top edge.

0:39:050:39:10

As the sun moves towards the west,

0:39:200:39:23

so this face becomes roastingly hot.

0:39:230:39:26

But the eastern face falls into shadow and remains relatively cool

0:39:260:39:32

and the termites stay at the temperature that suits them best.

0:39:320:39:37

Other termites escape the heat of the day

0:39:370:39:40

by retreating to deep cellars below their mounds.

0:39:400:39:43

But these magnetic termites colonise areas that flood during the

0:39:430:39:47

rainy season, and the ground beneath them is regularly waterlogged.

0:39:470:39:52

So their compass-like mounds are a response not just to the movement of the sun but to badly drained sites.

0:39:520:39:59

Here in South Africa, it can also get very hot, but there's no danger of flooding,

0:40:010:40:07

so termites can take refuge from the heat below ground, where it's cool and relatively stable.

0:40:070:40:14

But two million insects living below ground create a different kind of problem.

0:40:140:40:20

The air around them gets stale.

0:40:200:40:23

So termites need to have a way of linking the underground air

0:40:230:40:28

with the fresh air above, a ventilation system.

0:40:280:40:31

And they do that with this.

0:40:310:40:34

And to see how it works, you've got to look inside.

0:40:340:40:39

Using the latest scanning techniques, we can create a picture of the mound's interior.

0:40:410:40:48

An intricate network of passages lead to a central chimney.

0:40:480:40:52

Hot, stale air from the insect population below rises up through the chimney.

0:40:540:41:00

But the top of the mound is sealed, so how does this stale air escape?

0:41:030:41:09

The mound may look as though it has strong defensive walls like a fortress,

0:41:100:41:15

but in fact these walls are porous

0:41:150:41:18

and their primary purpose is to harness the wind.

0:41:180:41:22

Fresh air, blowing against the side of the mound, is forced through the tiny holes in these walls.

0:41:220:41:27

From there, it travels through the smaller tunnels until it reaches the central chimney.

0:41:270:41:34

Here, the cooler, fresh air mixes with the hot, stale air

0:41:340:41:39

rising from the insect community below.

0:41:390:41:42

Meanwhile, some air is blown around the side of the mound.

0:41:420:41:46

This creates a suction that pulls the stale air out of the chimney and out through the outer walls.

0:41:460:41:54

So an internal air current is created and the whole mound ventilated.

0:41:540:41:58

The mound's inhabitants spend most of their time close to or below ground level.

0:42:000:42:05

Beneath their living quarters,

0:42:070:42:09

there are garden chambers, where the termites cultivate a fungus

0:42:090:42:13

that rots the wood and vegetation they collect and make it digestible.

0:42:130:42:17

Farther down still, the queen lies in her own chamber.

0:42:180:42:23

Her huge body is a gigantic egg-producing factory.

0:42:250:42:29

She is so swollen that she can't look after herself.

0:42:290:42:33

The workers must constantly clean her and feed her with food from their own crops.

0:42:330:42:40

Her partner, with whom she founded the colony maybe 20 years ago,

0:42:400:42:44

is still with her and mates with her throughout her life.

0:42:440:42:47

She lays eggs at an extraordinary rate, as many as 30,000 a day.

0:42:500:42:55

As she produces them, so workers remove them from the royal chamber and take them to nurseries.

0:42:570:43:03

There they'll be fed on compost from the fungus gardens until they turn into adults.

0:43:030:43:09

The super-organism that lives in this great castle

0:43:140:43:19

crops the surrounding vegetation just about as severely as an antelope.

0:43:190:43:24

The density of individual termites around here is extraordinary, over 100,000 per square metre.

0:43:240:43:32

And just as there are lions and leopard that hunt antelope, so in the undergrowth

0:43:320:43:39

there are insect hunters which prey on the tiny herbivores -

0:43:390:43:44

the ants, the termites' ancient enemy.

0:43:440:43:47

Matabele ants, specialist termite hunters.

0:43:490:43:53

A scout has laid down a clear chemical trail,

0:43:590:44:04

and this battalion of workers have picked it up and are following it.

0:44:040:44:09

There may be only a few hundred of them, but they're going to severely

0:44:090:44:13

test the defences of a termite colony.

0:44:130:44:16

The mound has formidable guards, soldier termites.

0:44:230:44:26

The ants have a special technique for dealing with these soldiers.

0:44:390:44:43

They grab the termite's jaw

0:44:430:44:44

and then sting it in the only vulnerable place on its head, in its mouth.

0:44:440:44:49

The ants' front line breaks into the colony.

0:44:570:45:00

Reinforcements for the termite soldiers arrive quickly.

0:45:000:45:04

Already there are casualties on both sides.

0:45:040:45:07

But the invaders overwhelm the defenders.

0:45:100:45:13

It's not to the ants' advantage to kill an entire termite colony,

0:45:190:45:23

any more than it would be sensible for farmers to exterminate their cattle.

0:45:230:45:28

Better to let most survive, so that they can be regularly raided.

0:45:280:45:32

So although there are millions of termites in the colony, the Matabele

0:45:320:45:36

ants rarely go deep into the nest to press home their victory.

0:45:360:45:39

The raid lasts less than 15 minutes.

0:45:580:46:00

Nonetheless, the spoils are impressive.

0:46:010:46:05

Termite bodies are now being piled in dumps outside the nest.

0:46:140:46:18

Many of the casualties are still alive

0:46:280:46:30

but paralysed by the ants' stings.

0:46:300:46:33

Now the raiders have the considerable task of carrying their victims back to their nest.

0:46:330:46:39

They will have to take all their booty with them.

0:46:410:46:45

If any termite bodies are left behind they will be collected by scavengers.

0:46:450:46:49

The termite soldiers certainly fought hard.

0:46:530:46:56

One of their dead still grips a Matabele soldier in its jaws,

0:46:560:47:00

which it killed before it was itself slaughtered.

0:47:000:47:04

Well, it's been a successful raid.

0:47:120:47:15

Many of the bigger ones have got mouthfuls of termites.

0:47:150:47:19

How they manage to hold all of them in one mouthful I don't know,

0:47:190:47:23

but obviously they have got a little way to go now,

0:47:230:47:26

and soon the young ones back in the nest will be getting good food.

0:47:260:47:32

The Matabele ants will use their plunder to raise more workers.

0:47:340:47:38

Ironically, the raid will have the same effect on the termites.

0:47:380:47:42

The queen will detect the loss of her soldiers and workers

0:47:420:47:45

and will increase her output of eggs to repopulate the colony.

0:47:450:47:49

So there will be just as much food for the Matabeles the next time they raid.

0:47:490:47:54

The tiny creatures of the undergrowth

0:47:590:48:01

were the first animals of any kind to colonise the land.

0:48:010:48:06

They established the foundations of the land's ecosystems.

0:48:070:48:12

Ultimately they were able to transcend any limitations of their

0:48:120:48:16

small size by banding together in huge communities of millions

0:48:160:48:21

and putting up buildings like this one.

0:48:210:48:24

If we and the rest of the backboned animals were to disappear overnight,

0:48:240:48:29

the rest of the world would get on pretty well.

0:48:290:48:33

But if THEY were to disappear,

0:48:330:48:35

the land's ecosystems would collapse.

0:48:350:48:39

The soil would lose its fertility.

0:48:390:48:41

Many of the plants would no longer be pollinated.

0:48:410:48:45

Lots of animals - amphibians, reptiles, birds, mammals - would have nothing to eat,

0:48:450:48:50

and our fields and pastures would be covered with dung and carrion.

0:48:500:48:56

These small creatures are within a few inches of our feet

0:48:560:49:00

wherever we go on land, but often they're disregarded.

0:49:000:49:06

We would do very well to remember them.

0:49:060:49:09

Everyone ready?

0:49:200:49:22

Action.

0:49:240:49:26

Throughout Life In The Undergrowth, we've seen the most extraordinary creatures

0:49:280:49:32

living the most remarkable lives right under our noses.

0:49:320:49:36

But what's most remarkable

0:49:410:49:42

is that they are just the tip of the iceberg.

0:49:420:49:45

Of all the animals on the planet,

0:49:450:49:46

land-living invertebrates are the most numerous,

0:49:460:49:50

both in kinds and absolute numbers,

0:49:500:49:53

but, incredibly, we still know the least about them.

0:49:530:49:57

Thankfully, as we've found out in Fly On The Wall,

0:49:590:50:02

behind the scenes there are people out there every day

0:50:020:50:05

pushing the boundaries of our knowledge.

0:50:050:50:08

You might be surprised to hear

0:50:120:50:14

that even the world's largest insect is still almost unknown.

0:50:140:50:19

But in the depths of the Amazon, one man is trying to piece together a picture of its life.

0:50:190:50:25

Scientist Frank Hovore is on the trail of Titanus, the titan beetle.

0:50:280:50:35

Titanus isn't spectacular because of its beautiful colours or ornate structures.

0:50:350:50:39

It's spectacular because it's the size of your shoe.

0:50:390:50:42

There's a magic to that to those people who still have a little child inside them alive at all times

0:50:420:50:49

and are fascinated, moreover thrilled, at the prospect of seeing something like this in the wild.

0:50:490:50:57

But how do you find one particular beetle in the Amazon?

0:50:570:51:02

Frank's answer is light.

0:51:020:51:05

A bright light and a white sheet in a forest clearing is all you need.

0:51:050:51:09

The hope, that if you wait long enough, the titan will be lured into the light and will find YOU.

0:51:090:51:16

But it's not only titans that are attracted to light.

0:51:160:51:21

Frank is a world authority on the insects of the Amazon,

0:51:210:51:25

and so for him this is all part of the thrill of a titan hunt.

0:51:250:51:29

Every night there is something different.

0:51:310:51:34

Among these creatures

0:51:340:51:37

there may well be a dozen or so that no scientist has seen before,

0:51:370:51:42

let alone understood.

0:51:420:51:44

Ten inches...something...

0:51:450:51:49

That's an amazing nectar-gathering tube.

0:51:490:51:53

You would guess there must be a flower out here,

0:51:530:51:55

probably a tree, maybe a big acer,

0:51:550:51:57

something that has an enormous corolla to the flower. Now watch.

0:51:570:52:02

It'll just curl it right back up...

0:52:020:52:04

unharmed, unperturbed.

0:52:040:52:06

It's nearly dawn, and still no titan.

0:52:120:52:15

But beetles love moisture, so the rain is a good omen for tomorrow night.

0:52:150:52:20

The titan lives only for two weeks as a winged adult.

0:52:240:52:28

Like other beetles, it must spend most of its life, possibly years,

0:52:280:52:33

as a larva, but no-one has ever seen it.

0:52:330:52:36

By looking for other beetle larvae,

0:52:380:52:42

Frank can get an idea of how big it must be.

0:52:420:52:45

Well, here we go.

0:52:480:52:49

Here's our larva right here.

0:52:510:52:54

We pop the lid off of him,

0:52:540:52:56

or her, as it were,

0:52:560:52:58

and there we are.

0:52:580:53:00

This would be a harlequin beetle larva.

0:53:030:53:06

The harlequin is a big beetle but nowhere near the size of a Titanus.

0:53:060:53:10

The Titanus larva would be easily, oh, perhaps this much longer

0:53:100:53:15

and considerably greater girth.

0:53:150:53:18

If Titanus were in these logs, which clearly it is not,

0:53:180:53:23

you'd be able to slide your whole arm in there

0:53:230:53:26

and pull these things out like you were catching snakes.

0:53:260:53:29

The problem for Frank is that even after four expeditions in search of titan,

0:53:290:53:34

he's never found where such a giant larva could be hiding.

0:53:340:53:38

Is it this one here?

0:53:380:53:40

But an exciting new discovery gives him a clue.

0:53:400:53:43

Oh, yeah, look at this.

0:53:430:53:45

These great big circular holes there - look at that.

0:53:500:53:53

Holes big enough to put your hand through,

0:53:530:53:56

and they're certainly big enough to be Titanus.

0:53:560:53:58

I'm very, very strongly suspicious that when this tree was much younger

0:54:000:54:05

and this was not a rotted centre to it,

0:54:050:54:07

the Titanus were working up underneath the crown

0:54:070:54:10

and that this is their larval galleries.

0:54:100:54:12

It seems that the titan hides away for most of its life in the heart of living trees.

0:54:120:54:19

The picture of titan is getting clearer.

0:54:190:54:23

Back at the sheet, Frank is hopeful that the rain has had its effect and will bring out the beetles.

0:54:250:54:31

Oh, here we go.

0:54:330:54:35

This one is one of my favourite beetles

0:54:360:54:40

because it was named after me last year...

0:54:400:54:44

..Anicacerus hovori.

0:54:440:54:45

I'm very pleased to see him come into our light tonight.

0:54:470:54:51

Though he's not a Titanus,

0:54:510:54:53

I can live with that.

0:54:530:54:55

And it's biting me -

0:54:570:54:59

that makes it pretty cute.

0:54:590:55:01

And next, the spectacular adult form of that less-than-beautiful grub

0:55:020:55:07

that Frank found in the log, a harlequin beetle.

0:55:070:55:11

It's a female harlequin beetle. BUZZING

0:55:140:55:17

You hear the noise she's making?

0:55:180:55:20

It's a warning sound.

0:55:240:55:26

She's got spines at the side of the thorax,

0:55:260:55:30

spines on the humeri.

0:55:300:55:32

They come together, and if I put my finger in there, she'd poke me.

0:55:320:55:36

Even spines down here on the back side,

0:55:360:55:38

and the legs, like all of these insects, have hooks on 'em sharp enough

0:55:380:55:44

that just to touch your flesh they're immediately hooked in.

0:55:440:55:48

See it pulling me out there? She'd be a tough one.

0:55:480:55:51

The bigger the beetle, the more tempting to predators, and so the tougher it needs to be.

0:55:510:55:58

What the heck was that?

0:55:580:56:01

-Titanus!

-Titanus!

0:56:010:56:02

Oh, look at this!

0:56:020:56:04

-Look at this!

-Pretty good-sized one.

0:56:040:56:07

Yeah, he's a pretty good size. You gonna try to move that rock?

0:56:070:56:11

Hello!

0:56:110:56:12

Let's not go anywhere, shall we?

0:56:120:56:15

What an incredible beetle.

0:56:150:56:17

He's very strong.

0:56:180:56:20

You can feel his body temperature - he's hot.

0:56:220:56:24

Well hotter than the outside temperature.

0:56:240:56:27

He's ripping my flesh!

0:56:270:56:29

There's something primeval about the movements of this thing.

0:56:320:56:36

Those jaws going...

0:56:360:56:38

When so little is known about the titan,

0:56:410:56:44

just to record the sheer size of it,

0:56:440:56:46

what time it comes out, how warm it is, how strong it is, makes it all worthwhile.

0:56:460:56:52

That is a spectacular beetle.

0:56:530:56:54

All I can say right now is...

0:56:550:56:58

# Da-da-da! Da-da da!#

0:56:590:57:01

Titanus!

0:57:010:57:02

One day, Frank will find his giant larva, and each new encounter will

0:57:040:57:09

help build up a complete picture of the world's largest insect.

0:57:090:57:14

Thanks to people like Frank, we are getting ever closer

0:57:140:57:17

to an understanding of the creatures of the undergrowth.

0:57:170:57:21

But every night on Frank's sheet there are about 500 different kinds of invertebrate.

0:57:250:57:31

And that's just one sheet, in one clearing, in one patch of forest.

0:57:330:57:38

It's thought that there are ten million species of land-living invertebrates on the planet.

0:57:420:57:49

Of those, nine million are yet to be discovered.

0:57:490:57:53

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