Meet the 'Bone Collector' Caterpillar: A Rare Hawaiian Insect That Wears Its Prey and Lives Among Spiders

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26-04-2025

A rare Hyposmocoma caterpillar, nicknamed the "bone collector," discovered in Oʻahu, Hawaii, uses dead insect parts to disguise itself on spider webs
The newly identified species is carnivorous and cannibalistic, with a highly specialized habitat limited to just 5.8 square miles
Scientists warn the caterpillar is at risk due to invasive species and climate change threatening its already fragile ecosystem
In the secluded forests of Oʻahu, Hawaii, scientists have discovered a truly astonishing insect — one that not only hunts its fellow arthropods, but wears them.
Documented in a new study published in Science on Thursday, April 25, the insect is a newly described species within the Hyposmocoma genus, known for its bizarre behaviors and evolutionary surprises. Nicknamed the "bone collector," this rare caterpillar is as elusive as it is eerie, and may be unlike anything the scientific world has seen before.
The caterpillar cloaks itself in the body parts of dead insects, crafting a protective casing out of the remains to camouflage itself while lurking on spider webs. This survival tactic seems to allow the caterpillar to sneak past the very creatures that should be its predators: spiders.
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Researchers, led by entomologist Dr. Daniel Rubinoff of the University of Hawaii at Mānoa, believe the insect's gruesome disguise helps it hide in plain sight, feeding on prey caught in the web, sometimes even unwrapping the spider's own leftovers.
'It is possible the array of partially consumed body parts and shed spider skins covering the case forms effective camouflage from a spider landlord,' researchers wrote, per Science Alert. 'The caterpillars have never been found predated by spiders or wrapped in spider silk.' Essentially, the spiders have never been observed attacking or eating these caterpillars.
Another unusual trait is the caterpillar's exclusive choice of insect parts or spider exoskeletons for their casing, rather than natural materials like bark or leaves, when tested in a lab. Another jaw-dropping characteristic is their cannibalistic tendencies, as researchers found that they would eat any slow-moving insect placed in front of them, even each other.
'It is remarkable that a caterpillar would tie its fate to a spider — a clear and present danger for both caterpillar and moth alike,' Dr. David Wagner, an entomologist at the University of Connecticut, explained to the New York Times, calling the caterpillar's reliance on the spiders one of nature's most improbable connections. (Wagner was not involved in the study.)
Since Dr. Rubinoff first encountered the species in 2008 inside a tree hollow, his team has conducted more than 150 field surveys and found only 62 bone collector specimens. The caterpillar is now known to exist in a single forested mountain range, covering just 15 square kilometers (about 5.8 square miles).
Genetic analysis shows that this species may have diverged from its carnivorous cousins over five million years ago, predating the formation of the island of Oʻahu itself. That means its ancestors likely inhabited other Hawaiian islands before becoming isolated on the mountainside where it now survives.
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Of course, survival is far from guaranteed. The bone collector's habitat is increasingly under threat from invasive ants, parasitic wasps, and the ever-present pressure of environmental change due to climate change and human disturbances.
While the caterpillar appears adaptable — it lives on the webs of at least four non-native spider species — its narrow range and complex behavior make it particularly vulnerable.
"Without conservation attention, it is likely that the last living representative of this lineage of carnivorous, body part-collecting caterpillars that has adapted to a precarious existence among spider webs will disappear," researchers wrote, per Science Alert.
Read the original article on People