[MUSIC PLAYING] NARRATOR: Ever wish you could be invisible?

Fade into the background, unnoticed, unseen?

For glasswing butterflies, the rainforests of South and Central America are full of hungry predators they'd like to hide from.

Some butterflies use cryptic camouflage to hide themselves by blending in with their surroundings.

Others use aposematism, vivid colors and patterns that warn predators they're toxic.

Glasswings do have some warning markings.

See that bright slash of white on black?

But that's not their main defense.

Their transparent wings enable them to disappear into the background wherever they go, even while flying.

This little caterpillar is a baby glasswing, and it's already good at staying out of sight.

You can see through parts of its exoskeleton, offering a window into its most recent leafy meal.

That exoskeleton is made of a material called chitin that's both strong and flexible.

In most insects, chitin is mixed up with pigments that give it color, but some parts of the glasswing lack pigment entirely.

Once it's had its fill, the caterpillar suspends itself under a leaf or stem.

It becomes a chrysalis.

Inside, it's undergoing a metamorphosis.

About a week later, the transformation is complete.

An adult butterfly emerges.

It unfurls its delicate new wings, revealing its windowpanes for the first time.

At the Nipam Patel Lab at UC Berkeley, researcher Aaron Pomerantz is studying how exactly the glasswing butterfly forms those transparent wings.

They're made of that same clear chitin from when it was a caterpillar.

But in these wings, the chitin's all stretched out, incredibly thin and stiff, and that layer of chitin is exposed.

Other butterfly wings are covered in colorful overlapping scales that protect their wings from the elements.

The glasswing does have colored scales on its body and the fragile edges of its wings, but the scales on these windowpanes don't look like scales at all, more like tiny hairs.

They're skinny and spread out.

They let the light pass by.

But having clear wings doesn't help you hide if they're shiny.

Zoom way in, past the hairs, and you'll see the surface looks rough.

It's covered in miniature towers made of wax.

They're called nanopillars.

If the surface of the wing was smooth, light would bounce off of it.

The nanopillars are nature's original anti-glare layer coating.

Researchers found that when they used chemicals to remove the nanopillars, the wings glimmered more.

While some other butterflies gleam in the sunlight, the glasswing reflects almost no light at all.

Glasswings excel at being dull, and that helps them hide in plain sight.

What makes glasswings special isn't their luster, but their ability to fade away.

Hey, ya Deep peeps, it's Laura.

We've got more butterfly-themed Deep Look episodes for you, like why behind every beautiful butterfly there's a voracious caterpillar, and how blue morpho butterflies have some of the most brilliant blues in nature without any blue pigment at all.

Instead, they harness the physics of light at the nanoscale.

See you next time.