A newly discovered species of caterpillar in Hawaii is unlike any other. It's carnivorous — already an extreme rarity for these generally benign creatures — and when it's not devouring its helpless foes, it's cloaking itself in a gruesome canvas of their body parts. Oh, did we also mention it's occasionally a cannibal?

Taking trophies ranging from entire heads to molted exoskeletons, there's a reason why scientists have nicknamed it the "bone collector." As detailed in a study published in the journal Science, the caterpillars favor lurking in spider webs hidden from view, like in a tree hollow or rock cavity, where they strip the corpses of insects ensnared in the silk traps, and daringly avoid the detection of the arachnids that interred them there. And the caterpillars get away with it thanks to their macabre costumes, disguising them as the dead insects while also making them appear unappetizing to predators.

"We started realizing these things are only hanging out where there are spiders," lead author Daniel Rubinoff, an entomologist at the University of Hawaii, told Ars Technica. "It's the sort of thing you really want to be sure of because it's not just incredible, it's unimaginable."

"It is remarkable that a caterpillar would tie its fate to a spider — a clear and present danger for both caterpillar and moth alike," echoed David Wagner, an entomologist at the University of Connecticut who was not involved in the study, to the New York Times.

The bone collector belongs to a genus of moths found in Hawaii called Hyposcoma, which are known for spinning protective cases of silk when they're larva. In this case, the silk is used to weave the body parts together, forming a sort of portable cocoon.

Rubinoff first stumbled across a specimen in 2008, and has since worked to prove that the caterpillars are an entirely new species. Bone collectors are found exclusively in the Wai'anae Mountains on the island of O'ahu, and are exceedingly rare. To date, more than 150 field surveys in the area have yielded only 62 specimens, per the NYT.

The bodypart camouflage may look random and haphazard, but it's apparently a carefully curated outfit. Somewhere between mortician and tailor, a bone collector will use its mandibles to cut a beetle carapace here and an ant limb there down to size, and are notably picky when it comes to choosing what to add to their suits (though what informs its fashion choices is unclear). In a lab, bone collectors ignored random detritus and went straight for the dead stuff, showing that they were "able to discern differences in objects in their environment," Rubinoff told the NYT. But they ate practically any insect.

By studying the caterpillar's genetics, Rubinoff and his team revealed that the species likely emerged at least five million years ago, which is older than O'ahu itself. Because it has no relatives of the same lineage, the researchers believe its original home was another island that's since been swallowed by the ocean, per Ars.

Resourceful as they are, the bone collectors are tragically being threatened by a surge of invasive bug species, and could face extinction.

"I don't want to say it's on the verge of winking out, but in the context, it seems likely," Rubinoff told Ars. "We've lost entire genera of endemic insects [in Hawaii]. It could be one new ant species away from being obliterated."

More on wildlife: Scientists Take First Ever Video of Colossal Squid in the Wild... With One Comical Issue


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