Stinging nettle (Urtica dioica L.; Urticaceae), a Holarctic perennial herb, is a host plant of two lygaeoids of the family Heterogastridae: Heterogaster urticae (F.) in the Palearctic and H. behrensii (Uhler) in the Nearctic Region. We give the first published North American records (other than port-of-entry interceptions) of H. urticae, based on fieldwork in British Columbia in 2010 and 2011. We also give new distribution records for H. behrensii, a species of special concern in the province; it previously was known in Canada only from one site in British Columbia. Morphological characters are provided to distinguish the species. Both heterogastrids were collected from stinging nettle in British Columbia's Lower Fraser Valley and on Vancouver Island; H. urticae also was taken in the Vancouver Metro Area. The species were syntopic in two nettle colonies. We suggest that the heterogastrids'syntopy provides an opportunity to determine whether the adventive H. urticae might adversely affect the native H. behrensii.