Review of the literature and regional faunal lists identifies 14 species of Noctuoidea that are established in the Pacific Northwest (PNW) region of North America following non-deliberate introduction to the continent by man. The year that each species appeared in the region is estimated by literature review and search of regional museums. The source of each species and mode of introduction to the PNW are estimated, suggesting that over half of these species were first introduced to North America in the PNW and that most originate from western Eurasia (Europe). Their larvae are most commonly polyphagous, favoring forbs, but several recently introduced species eat grasses. Mesapamea secalis (L.) is reported for the first time for North America from southwestern British Columbia, Canada and western Washington, USA. The adults and genitalia of both sexes are described, illustrated, and compared to those of similar native species. The potential economic impact of M. secalis in North America is discussed.