And in harvester ants, I divide the tasks of the ants I see just outside the nest into these four categories where an ant is foraging, when it's out along the foraging trail, searching for food or bringing food back.

She lays eggs, she feeds the larvae so an ant starts as an egg, then it's a larva.

But in a small colony, it's likely to meet fewer foragers, just because there are fewer other foragers there to meet.

The nest maintenance workers become foragers.

Like I just said, if there is more food to collect, the patrollers, the midden workers, the nest maintenance workers will all change to forage.

Does it matter to the foragers what the nest maintenance workers are doing?

What shall they eat?

So for example, if I put out extra food, everybody else the midden workers stop doing midden work and go get the food, they become foragers.

So it has to know the difference between a forager and a nest maintenance worker.

When the foragers come in with food, they just drop it into the upper chamber, and other ants come up from below, get the food, bring it back, husk the seeds, and pile them up.

They bring it back and feed it to the larvae.

When extra food becomes available and this is what everybody knows about picnics then extra ants are allocated to collect the food.

There's the larvae, and they consume most of the food.

It's surely an animal or night prowler.

The simplest idea is that when an ant is in a small colony and an ant in a large colony can use the same rule, like I expect to meet another forager every three seconds.

I expect to meet another forager every so often.

But first you might be wondering how is it that an ant can tell, for example, I'm a forager.

They somehow choose the direction that the foragers will go, and by coming back just by making it back they tell the foragers that it's safe to go out.

She feeds the larvae by regurgitating from her fat reserves.

So for example, if I make a mess that the nest maintenance workers have to clean up, then I see fewer ants out foraging.

But the foragers somehow decide not to come out.

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Ants never make more ants colonies make more colonies.

And one of the things that we're studying is how natural selection might be acting now to shape this use of interaction patterns this network of interaction patterns to perhaps increase the foraging efficiency of ant colonies.

So foraging acts as a sink, and the ants inside the nest act as a source.

Ants are a classic example workers work for queens and queens work for workers.

Now ants most ants, including these, don't see very well.

So it starts out with zero ants, just the founding queen, and it grows to a size of about 10 or 12 thousand ants when the colony is five.

And then I encouraged the ants to come 'round by putting sugar and things like that.

But if instead I start to meet a higher number of nest maintenance workers, I'm less likely to forage.

And when we dig up nests we find they're about as deep as the colony is wide, so about a meter deep for the big old nests.

So, the ants in the older colony that seem to be more stable are not any older than the ants in the younger colony.

So that's only about 25 percent of the colony, and they're the oldest ants.

They go out, they get the food, they dig the nest, and the queen never comes out again.

No ant directs the behavior of any other ant.

Narrator The mechanical beasts will not get their energy from food, but from the wind.

And so my house came down, I received my first patent against carpenter ants, termites and fire ants.

When one ant touches another, it's smelling it, and it can tell, for example, whether the other ant is a nest mate because ants cover themselves and each other, through grooming, with a layer of grease, which carries a colony specific odor.

And these four groups are just the ants outside the nest.

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And they do that by each year sending out the reproductives those are the ones with wings on a mating flight.

They are looking at how ants and bees find their food and their flowers in the most effective way as a whole hive.

So this is the colony founded by a queen the previous summer.

And the nest maintenance workers do that inside the nest, and then they come out of the nest carrying bits of dry soil in their mandibles.