The years of first findings of Ctenolepisma longicaudatum from northern European countries and regions. The source references are: Belgium (Lock 2007), United Kingdom (Goddard et al. 2016), The Netherlands (Nierop and Hakbijl 2002, Schoelitsz and Brooks 2014), Germany (Meineke and Menge 2014), Denmark (Thomsen et al. 2019), Poland (Aak et al. 2019), Faroe Islands (Thomsen et al. 2019), Norway (Aak et al. 2019), Sweden (Pape and Wahlstedt 2002, Shah and Coulson 2020), Finland (Ueda 2020), NW Russia (Ueda 2020), Estonia (original data), Lithuania (Ueda 2020). The asterisk indicates a suspicion of an earlier observation (Schoelitsz and Brooks 2014, Thomsen et al. 2019, Anders Aak, pers. comm.).