That leaf she's gnawing on is no flower.

But this is an alfalfa leafcutting bee.

She needs hunks of leaves to build her nest.

A lot of them.

All this is her lacy handiwork.

She hauls the pieces back home.

Leafcutters use them to line the inside of their nest.

In nature, she might use a nook and cranny in a log.

But here, her nest is in what's basically a bee apartment building.

A high-rise made of Styrofoam.

These markings help the bee find her way back to her personal condo.

You know, like, 7B.

And furnishing it takes a while, because, see that pile?

These are the pieces they dropped.

The bees are here to work in this alfalfa field in California.

They're from Europe originally, but farmers here use them because they have a real knack

for pollinating alfalfa flowers, which grow tiny seeds inside these curly pods.

Farmers use the seeds to plant new fields of alfalfa ...

… which is grown to make hay ...

… to feed these gals.

So, really, your glass of milk comes courtesy of these bees.

But pollinating alfalfa flowers is a lot trickier than it looks.

Even honeybees can't really hack it.

Here's why.

Alfalfa keeps its pollen locked away inside its flowers.

To get it, the bees have to step on a spring-loaded petal called a keel petal.

Here's how it works.

Pop!

It releases this column that has the pollen at the end.

It's called “tripping” the flower.

Here it is again.

The column has some force – the bee might get a good thwack in the face.

Leafcutting bees just don't care; they can take a punch.

Pop.

Pop.

Honeybees don't really like to tangle with that.

They'll usually step around gingerly, trying to sip nectar from the side without setting

it off.

Leafcutting bees get coated in pollen and bring it back home to their nest so they can

pack it in there to feed their growing babies.

Each one is bundled in a little leaf-wrapped bassinet.

Aw, there they are.

The siblings all lined up together.

A new generation of the toughest little bees around.

Hi.

It's Lauren.

We want to do something extra special: a filming expedition to Oaxaca, Mexico.

If just 1 in 1,000 of you support us on Patreon, this trip is totally on.

Let's do this.

Link in the description.

One more thing.

Our partner, PBS Digital Studios, wants to hear from you.

It's a survey, so we can make even better shows.

It takes about 10 minutes and you might win a sweet T-shirt.

That link is also in the description.

Thanks!