Once upon a time, the Argentine ant seemed invincible.

Why?

Well normally, ants in different colonies of the same species fight each other to the death for territory and food.

But take an Argentine ant from a colony in Japan, or Spain, or from your kitchen, put 'em together and...

Nothing happens.

They recognize each other by smell.

Just like these nest mates.

Worldwide, Argentine ants act like a huge, international super colony.

Countless nests, each home to hundreds of queens, producing millions of highly disposable workers.

Massive Argentine ant super-colonies are spreading all over the globe, overwhelming local ant populations.

They can take down much bigger ants.

Like this harvester.

The tiny Argentines throw themselves at their enemy.

Exhaust her.

Then slowly pull her apart.

They seemed unstoppable.

But there's more to this story.

The Argentine ant has an Achilles heel.

At Jasper Ridge, near Stanford University, Nicole Heller has been tracking ant populations since the late 1990s.

She wanted to know, how long would it take for Argentines to completely overwhelm the native species here?

One year?

Five?

But it didn't happen.

To her surprise, one native species was actually thriving behind enemy lines.

The winter ant.

Winter ants aren't much bigger than Argentine ants.

They aren't much stronger.

But they have a secret weapon.

Put Argentine and winter ants together near something they both want, like this cotton ball soaked in honey.

See how the winter ant aims its abdomen at the Argentine?

And that little white dot appears right at the tip?

And how the Argentine scurries away?

No one had ever seen this before.

In fact, as far as we know, this is the first time anyone's caught it on camera.

No one knows yet what exactly it is, but this secretion can repel, even kill, those Argentine workers.

At Jasper Ridge, this little drop has been enough to halt an implacable invader's march toward world domination.

Hi, it's Amy.

See how these ants all tap each other when they go by?

Well when ants touch antenna, they're not just exchanging information...they ARE the information.

They switch jobs based on how many other ants they run into doing the same thing.

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