The Bone Collector: The Caterpillar That Wears Dead Bodies

Forget butterflies.

Somewhere in the forests of Hawaii, there is a caterpillar that lives inside a spider's web, steals the spider's leftovers, wears dead insects on its back, and eats other caterpillars.

And somehow, scientists think it's kind of adorable.

Meet the bone collector caterpillar.

Yes. That is its actual nickname.

This Is Not The Very Hungry Caterpillar

In April 2025, researchers from the University of Hawaiʻi at Mānoa revealed one of the strangest creatures ever documented.

They found it in the Waiʻanae mountains on Oʻahu, living inside spider webs.

At first, they weren't even sure they were looking at a caterpillar.

It looked more like a tiny moving sack of rubbish.

Then the sack moved.

Inside was a caterpillar.

And on top of the caterpillar?

Dead insects.

Fly wings. Ant heads. Beetle parts. Weevil heads. Earwig remains. Even pieces of dead spiders.

It had basically turned itself into a walking corpse collection.

Nature had invented a goth handbag.

It Lives In A Spider's Web

This is where things get ridiculous.

Most caterpillars eat plants. Leaves, flowers, stems, the usual green buffet.

The bone collector decided that was boring.

Instead, it lives inside spider webs and eats insects that the spider has already caught.

Think about that for a second.

The caterpillar has moved into the spider's house.

The spider's house is a giant trap designed to catch and kill things like caterpillars.

And the caterpillar is sitting there eating the spider's leftovers.

It's essentially living inside a lion's kitchen and ordering takeaway.

Researchers believe this works because the caterpillar isn't behaving like prey.

By covering itself with insect remains and shed material from the web, it appears to disguise its presence as nothing more interesting than discarded spider debris.

In other words:

It evolved to look like garbage.

And somehow, that is brilliant.

But Why Wear Corpses?

The bone collector belongs to the Hawaiian moth genus Hyposmocoma, whose caterpillars are famous for building portable silk cases.

Other species decorate their cases with things like wood, algae, or shells.

The bone collector looked at the family tradition and apparently decided:

"What if we used dead bugs?"

Researchers observed the caterpillars selecting pieces of insects and attaching them to their silk cases.

And they weren't just randomly grabbing whatever was nearby.

They appeared to choose specific pieces and adjust them to fit.

Give one a collection of ordinary materials and insect remains, and it will repeatedly choose the dead insects.

It's not decorating.

It's curating.

The caterpillar isn't carrying luggage.

It's carrying trophies.

And Yes, It Eats Its Own Kind

Here's where the story gets even darker.

Researchers placed two bone collector caterpillars together.

The larger one attacked and ate the smaller one.

So much for community spirit.

This may help explain why researchers typically find only one bone collector living in a spider web.

There is no shared apartment.

No caterpillar flatmate situation.

Just one tiny corpse-wearing predator enjoying an all-you-can-eat buffet.

And if another bone collector moves in?

The buffet gets a new item.

It's Older Than Oʻahu

Here's the part that makes this creature even more fascinating.

Genetic evidence suggests the bone collector's lineage separated from other Hyposmocoma moths at least six million years ago.

That's older than the modern island of Oʻahu.

Its ancestors likely lived on older Hawaiian islands that have since eroded and disappeared beneath the Pacific.

Over millions of years, their descendants moved through the Hawaiian archipelago and evolved into increasingly specialised creatures.

The bone collector found one particularly bizarre niche:

live in spider webs, steal spider food, and wear dead insects.

Evolution really does have an imagination problem.

Except this time, the problem is that it has too much imagination.

And There Are Barely Any Left

Despite surviving for millions of years, the bone collector is now extremely rare.

After more than two decades of field surveys, researchers documented only 62 individuals.

The species survives in a tiny area of forest, roughly 15 square kilometres.

And it faces threats from invasive species, feral pigs, and habitat loss.

Which means this bizarre little creature may disappear before most of the world even knows it exists.

That's the strange tragedy of evolution.

A creature can survive for millions of years, develop one of the most absurd survival strategies imaginable, and still be defeated by a habitat disappearing underneath it.

Nature Didn't Get The Memo

We tend to imagine evolution as a process that produces elegant things.

Wings.

Camouflage.

Sharp claws.

Speed.

The bone collector went in another direction.

It became a caterpillar that:

• lives inside spider webs
• steals the spider's food
• wears dead insects
• disguises itself as rubbish
• hunts other caterpillars
• and occasionally eats its own kind

And somehow...

it works.

That's what makes the bone collector so fascinating.

It isn't a monster.

It isn't a failed experiment.

It is an extraordinarily specialised survivor.

Millions of years of evolution looked at a tiny Hawaiian forest and arrived at this:

"Let's make a caterpillar that wears corpses."

And nobody can argue with the results.

So the next time you see an ordinary caterpillar quietly chewing on a leaf, spare it a little respect.

Because somewhere in Hawaii, its much stranger cousin is crawling through a spider's web wearing a weevil's head on its back.

And honestly?

We have absolutely no idea what evolution is going to come up with next. 🐛💀