Philodoria nigrelloides is a moth of the family Gracillariidae. It was first described by Otto Swezey in 1946. It is endemic to the Hawaiian island of Kauai. First identified in 1946 by entomologist Otto H. Swezey from a single male specimen collected at 4,000 feet in the Alaka'i Swamp, the moth has a wingspan of roughly 8 mm. It is distinguished by bronzy-brown forewings adorned with white streaks and spots, including a slanted white band and a blue marking with a black center near the termen.
The larvae feed on the leaves of the Dubautia species, forming characteristic mines within the foliage of these native Hawaiian plants. Initially placed in the genus Parectopa, the species was later reassigned to Philodoria, a group of 51 Hawaiian-endemic gracillariid moths known for their specialized leaf-mining habits on vulnerable native plants. Despite repeated surveys in areas where it was historically found, P. nigrelloides has not been recorded since its original discovery, and by 2021, it was considered likely extinct. Its disappearance highlights the fragility of Hawaii's distinctive invertebrate fauna, particularly in the face of habitat loss and invasive species.