Species. Includes any species or subspecies of fish, wildlife, or plant, and any distinct population segment of any vertebrate species that interbreeds when mature. Excluded is any species of the Class Insecta determined by the Secretary to constitute a pest whose protection under the provisions of the Act would present an overwhelming and overriding risk to man.
50 CFR § 424.02
The definitions contained in the Act and parts 17, 222, and 402 of this title apply to this part, unless specifically modified by one of the following definitions. Definitions contained in part 17 of this title apply only to species under the jurisdiction of the U.S. Fish and Wildlife Service. Definitions contained in part 222 of this title apply only to species under the jurisdiction of the National Marine Fisheries Service.