Moths (Order Lepidoptera) are a diverse and ecologically important group, and there is much to learn about their distribution and status in northeastern North America. Moth biogeography in Maine is not well understood, especially among offshore islands. The objective of this study was to document species diversity and phenology on Metinic Island, Knox County, Maine (Maine Coastal Islands National Wildlife Refuge). Handmade bucket light traps were deployed in forested and graminoid habitats from 13 May 2023 to 26 July 2023 during 13 sampling events. Moths were photographed and carefully released. Capture totals included 687 individuals from 124 species representing 17 families. Species richness and abundance peaked in early July. One notable species was the Slender Clearwing (Hemaris gracilis), a Species of Greatest Conservation Need (SGCN) in Maine. A better understanding of Maine's coastal moth diversity can help inform habitat conservation and management decisions.