The New “Bone Collector” Caterpillar Adorns Itself with the Remains of Its Prey.

A newly identified species of caterpillar has been found climbing the spider webs on Oahu, Hawaii, presenting an unprecedented sight for scientists.

This caterpillar not only thrives in a peculiar and precarious environment but also resides in tree hollows, rock crevices, and within the nets of curled logs. Interestingly, it is carnivorous and uses parts of its prey as camouflage after consuming them.

This unusual insect, recognized by researchers, is a rare outlier in the insect kingdom. Out of roughly 200,000 known species of moths and butterflies, only about 0.1% are carnivorous.

“Carthymen are extremely uncommon among caterpillars,” stated Professor Adam Hart, an ecologist, conservation scientist, and entomologist at the University of Gloucestershire who was not part of the study, as reported by BBC Science Focus. “In fact, it’s only found in Hawaiian species groups.”

This newly discovered species is adept at scavenging. It consumes weak or deceased insects that become ensnared in spider webs and can even chew through silk to access its food source if needed.

Dragging a silk case (the protective outer layer before transforming into a moth), it accumulates adhesive threads, exoskeletons, and insect limbs, creating a creepy yet effective disguise.

Researchers uncovered body parts from over six different insect species attached to these caterpillars. This is not a random assortment but a carefully curated collection.

“Before caterpillars weave their collection, the body parts are meticulously sized,” explained the authors of the published study in Science.

The parts are arranged optimally, with oversized pieces being bitten down to size before being incorporated, resulting in a creepy yet intentional suit of armor fashioned from the remains of their prey.

“Many caterpillars possess incredible camouflage, typically integrated into their form and behavior,” Hart noted. “It’s rare for them to utilize their environment as camouflage in this manner, but it’s not unheard of in moths; for instance, bagworms use environmental materials to construct their cases.”

To further explore this species, researchers raised some caterpillars in captivity, where they soon observed another unsettling behavior: cannibalism. The solitary nature of these caterpillars in the wild may explain their isolation, as only one is found per web.

The researchers also tested whether bone collectors would use other types of debris for decoration, finding they only decorated with insect remnants.

Despite its peculiar lifestyle, this species has existed for a lengthy period, potentially six million years, which is more than twice the age of Oahu itself.

However, its current range is limited to just 15km² (5.8 square miles) and is at significant risk of extinction. Without immediate conservation efforts, researchers warn that “the last living representative of this lineage of carnivorous, body-adorned caterpillars will vanish, adapted to the precarious existence within spider webs.”

“There are countless extraordinary invertebrates out there, with much more yet to be discovered,” Hart remarked. “Moth caterpillars disguised as the remains of insect prey, living predatory lives on spider webs, is certainly one of the strangest and most fascinating things I’ve heard in quite a while.”

About our experts

Adam Hart is an entomologist and professor of science communication at the University of Gloucestershire. Besides his research and educational efforts, he frequently appears on BBC Radio 4 and BBC World Service, participating in documentaries on various topics from trophy hunting to tree diseases. He also hosts a weekly science program, Science Behaviour for BBC World Services. On television, Adam has co-presented several documentary series, including BBC Four’s Planet Ant and BBC Two’s Living Hive.

Read more: