The 183 species of Lepidoptera recorded from Bermuda are discussed with respect to their world distribution, origin, long-range dispersal capability, host plants, nomenclature, and the circumstances of their occurrence in Bermuda; most are illustrated. Fifty-nine species are reported from Bermuda for the first time; Oenobotys invinacealis Ferguson (Pyralidae) and Tetanolita mynesalis inaequalis Ferguson (Noctuidae) are described as new. Four new genus–species combinations and four new synonymies are proposed.The Bermuda islands have a distressed fauna dominated by introduced pest species and migrants from the North American mainland and Caribbean Region. About 125 of the 183 recorded species are thought to be established residents; the remainder are assumed to be vagrants. Of approximately 50 resident species identified as probably indigenous, 11 species and three subspecies are endemic, and one of these, Semiothisa ochrifascia (Warren), is believed extinct.All Bermudian Lepidoptera are of American origin except the few introduced Old World species that are nearly cosmopolitan. Like Norfolk Island, Australia, Bermuda has a supersaturated lepidopterous fauna — more recorded species than its land area might support, which can be explained only by a high incidence of migrants and transients. This migratory component is explained relative to long-range movements of the same or congeneric species elsewhere; and hypotheses are proposed concerning the natural history of long-range dispersal in eastern North America and the ability of these moths to reach Bermuda. From a list of 113 species of Lepidoptera identified as frequent south–north migrants on the mainland, 76 are recorded from Bermuda. These include 38 of the 40 best-known cutworm moths of the eastern United States. It is argued that such moths reach Bermuda repeatedly without man's assistance and must regularly travel similar distances in North America.