We here describe five new species of Hawaiian fancy case caterpillars, Hyposmocoma Butler (Lepidoptera: Cosmopterigidae), from East Maui: Hyposmocoma (Hyposmocoma) starrorum sp. n., H. (H.) kukilakila sp. n., H. (H.) makaohuna sp. n., H. (H.) kamehamenui sp. n., and H. (H.) desilvai sp. n. They were collected during biodiversity surveys of the recently established Kamehamenui State Forest Reserve. All newly described species are endemic to East Maui, and likely even restricted to particular parts of Haleakalā. They represent a fraction of the undescribed diversity in the endemic genus Hyposmocoma and the discovery of these new species suggests that conservation initiatives and access to reserves will reveal significant additional diversity in one of Hawaiʻi’s most diverse adaptive radiations.