The Chuuk flying fox or Ruck flying fox (Pteropus insularis) is a species of flying fox in the Pteropodidae family. It is endemic to Micronesia. Its natural habitat is subtropical or tropical dry forests. The threats to the species are not well known, however since the species is found on a small area (the two islands of Chuuk Lagoon and Namonuito Atoll), the species was classified as "Critically Endangered" by the IUCN in 2009.