Hyposmocoma is a genus of moths with more 350 species endemic to the Hawaiian Islands whose larvae are referred to by the common name of Hawaiian fancy case caterpillars. The genus was first described by Arthur Gardiner Butler in 1881. Most species of Hyposmocoma have plant-based diets, but four species, such as Hyposmocoma molluscivora, eat snails. The caterpillars spin silk, which they then use to capture and eat snails. These are the first caterpillars known to eat snails (or mollusks of any kind). One unnamed species in the genus, dubbed the "bone collector", lives in association with spiders, forming a case from the shed body parts from the spider and remnants of the spider's prey items, providing camouflage while it feeds on discarded prey in the spider's web.

Some species feature amphibious caterpillars. This trait has evolved at least three times within this genus.

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