This is an extremely diverse group, and we are just beginning to get a more solid understanding of the evolutionary history of this complex assemblage; due to the changing nature of the higher level systematics, this group has recently been variously defined as a single family (Noctuidae in the sense of Lafontaine and Fibiger 2006) or numerous families (Mitchell et al. 2005b). Th e most recent phylogenetic analysis using an extensive molecular character set (Zahiri et al. in press) substantiates earlier findings, and more importantly shows that there are four well-supported family groups with other taxa subordinate within these. The family-level nomenclature and systematic order was adjusted accordingly for the North American Noctuoidea by Lafontaine and Schmidt (in press), and we use the same arrangement here. It is hoped that the resulting classification is more natural, more phylogenetically sound, and therefore more stable, although it has created some short-term confusion through the redefinition, renaming, and reorganization of some long-standing groups. As a result, the long-standing family-level groups Arctiidae and Lymantriidae have been relegated to subfamily status within the Erebidae, and a number of new subfamily names and groupings have appeared that will be unfamiliar to many.

This group contains approximately 58 500 described species in 4200 genera worldwide, and has traditionally been divided into a trifine group and a quadrifine group, on the basis of details of the hindwing venation (for details, see Lafontaine and Fibiger 2006). Th is corresponds largely to the Erebidae (quadrifines) and Noctuidae (trifines), although the trifine condition is thought to have arisen independently several times.

In the preceding sections dealing with the microlepidoptera and the non-noctuoid macromoths and butterflies, each group is discussed briefly at the family level, and the AB fauna are placed into context within the North American and global faunas. Similar treatment for all families and subfamilies of the noctuid groups is not possible at this time, because of the many recent rearrangements in the higher classification, and because the global composition of many groups has not yet been reconciled with the new classification system.

Approximately 3 800 species of Noctuidae (in the broad sense) are known from North America north of Mexico; 768 species are reported here from AB. Besides coverage in the general Lepidoptera texts discussed in the introductory sections of this book, useful general works about the Noctuidae include those by Rockburn and Lafontaine (1976) and Rings et al. (1992). Larvae of the Noctuidae were treated by Crumb (1956).