Hawaiʻi’s bone collector caterpillar wears spider’s victims to survive

A unique species of carnivorous caterpillar in Hawaiʻi has been identified by researchers. Known as the “bone collector,” this caterpillar is part of the Hyposmocoma genus, also called “fancy case” caterpillars because they create ornate protective cases to live in. Endemic to Hawaiʻi, these caterpillars camouflage their cases with materials like moss or sand. The bone collector is distinctive for encasing itself in inedible insect parts, providing protection from spiders while scavenging in their webs for food.

Unlike typical caterpillars that hide to avoid predators, the bone collector stands out by mimicking discarded prey to deter spiders. This behavior allows them to access food trapped in the spider’s web without being eaten. The bone collector is a rare species among about 600 fancy case caterpillars, each categorized by unique case shapes. Researchers found through DNA analysis that the bone collector lineage diverged from other Hawaiʻian carnivorous caterpillars around 6 million years ago, predating the formation of the Hawaiʻian Islands.

The adaptation of Hawaiʻian caterpillars varied on different islands due to local conditions. The bone collector, found only on Oʻahu in a small forest area, faces threats from habitat loss and invasive species. Evolutionary biologist Naomi Pierce from Harvard University expressed concern over the limited habitat of the bone collector, emphasizing the need for conservation efforts. Lead researcher Daniel Rubinoff highlighted the potential applications of studying caterpillar genetics and behavior for developing environmentally friendly pest control methods.