This special issue of ZooKeys is the third volume in a series on the systematics of New World macromoths. Fourteen authors have contributed 13 manuscripts for this volume, covering taxa in the Noctuidae, Erebidae, Notodontidae, Geometridae and Crambidae. New taxa are described from Argentina, Bolivia, Canada, Chile, Costa Rica, Peru and United States. Taxonomic changes include the description of two new genera, seven new species, and a new subspecies. Also, 45 new or revised synonyms, six new or revised statuses, and 20 new or revised generic combinations are proposed.