The taxonomic position of the family Castniidae within the order Lepidoptera has changed over time. Initially, it was classified in the superfamily Sesioidea, and then it was grouped in a large assemblage including the Cossoidea, Sesioidea, and Zygaenoidea. Recent studies have included it in the superfamily Cossoidea. In Europe, the palm borer moth (PBM) Paysandisia archon is the only species of the Castniidae. This moth, native to South America (Argentina and Uruguay), was first reported in Europe (France and Spain) in 2001, but it is believed to have been introduced before 1995 on palm trees imported from Argentina. Since then, the moth has been reported in Belgium, Bulgaria, Cyprus Island, Croatia, the Czech Republic, Denmark, France, Greece, Italy, Slovenia, Spain, Switzerland, and the United Kingdom. All known hosts are palms (family Arecaceae). The moth appears to have a wide host range, including the native Mediterranean palms but also exotic species, threatening ornamental and patrimonial palms, as well as date palms in North Africa. In Europe, the adult moths are active during the hottest part of sunny days, from mid-May to September–October, with a peak during June and July. PBM overwinter as larvae. Cocoons can be found from mid-March to mid-September. During the summer, all of the developmental stages of the moth (egg, larva, pupa, and adult) can be observed. Recent research has aimed to provide a more comprehensive understanding of the PBM's biology and host palm tree range under European Mediterranean conditions, to fill the knowledge gaps, support decisions for risk assessment, and improve monitoring, management, and regulation.