Researchers Uncover Unusual Carnivorous Caterpillar Camouflaging with Dead Insect Parts to Deceive Spiders

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The species, dubbed the “bone collector,” belongs to an ancient lineage of moths older than the Hawaiian island of Oahu, which is the only place it’s known to live today

Margherita Bassi

April 28, 2025 1:46 p.m.

In a remarkable discovery in Hawaii, researchers have identified a rare carnivorous caterpillar exhibiting a bizarre and intriguing behavior: it camouflages itself using remnants of insects while infiltrating a spiderweb, subsequently consuming the weakened or deceased prey trapped within. Coined the “bone collector,” this caterpillar has been formally characterized in a recent study published in the journal Science.

“It was astonishing. Initially, I thought my observations must be erroneous or singular,” states Daniel Rubinoff, the lead author of the study and an entomologist at the University of Hawaii at Manoa. He shared with Scientific American’s Gayoung Lee that after a decade of encountering this species, it continues to amaze him.

“This research represents an exceptional field study,” remarked evolutionary biologist David Lohman of the City College of New York, who was not involved in the research, in comments to National Geographic’s Carolyn Wilke.

Caterpillars are the larval forms of moths and butterflies within the Lepidoptera order. While most Lepidoptera are herbivorous, only about 0.1 percent are known to exhibit carnivorous tendencies, as noted in a recent statement.

The “bone collector” belongs to the genus Hyposmocoma, an ancient group of moths endemic to Hawaii. Remarkably, through 20 years of field observations, only 62 of these caterpillars have been documented, all concentrated on a single mountainside on Oahu.

Beyond its scarcity, Rubinoff emphasizes the caterpillar’s peculiar behavior. Hyposmocoma larvae create protective silk cases around themselves, which they carry until they metamorphose into adult moths. Unlike other species that use natural materials like shells or algae for camouflage, the bone collector opts for a more macabre decoration—bits of deceased insects scavenged from nearby spider habitats.

In an interview with New York Times’s Jack Tamisiea, Rubinoff mentioned that this behavior was previously undocumented, noting that the cases of these caterpillars contained remains from six different insect families, including beetles and arachnids.

“While it might sound unappealing at first glance, there’s also a certain charm to it,” he remarked in conversation with National Geographic. “It’s fascinating to see them inspecting and choosing their food sources with care.” In controlled observations, the caterpillars displayed preferences for insect parts, even altering the size of these components to better suit their needs. Cannibalism among them has also been recorded when they are in close proximity.

Choosing to live in a spider’s domain is a curious survival strategy for this caterpillar, given that spiders are their own predatory species. Rubinoff suggested this scenario could be likened to existing in a “lion’s den.” Nonetheless, no evidence thus far points to spiders preying on these distinctive caterpillars, hinting at an unorthodox but successful evolutionary adaptation. “The isolated environment of Hawaii has led to some remarkable evolutionary paths that defy typical biological norms,” he elucidated.

However, the bone collector’s endemic nature and limited range render it susceptible to various environmental threats, including habitat degradation and the encroachment of invasive species. According to researchers, analyses indicate that this maligned species predates the formation of the Oahu island by about three million years, suggesting a broader historical range across other regions.

“We are genuinely concerned about the need for enhanced conservation efforts,” Rubinoff noted in remarks to Associated Press’s Adithi Ramakrishnan.

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