The maple leafcutter moth (Paraclemensia acerifoliella (Fitch) (Lepidoptera: Incurvariidae) has been discovered in western Canada, feeding on saskatoon (Amelanchier alnifolia (Nuttall) Nuttall ex Roemer (Rosaceae)), a previously undocumented host. New records are detailed, and historical records are reviewed and assessed. Western populations are compared morphologically, genetically, and ecologically to populations feeding on maple (Acer Linnaeus; Sapindaceae) in eastern Canada. Paraclemensia Busck species host plants are discussed in relation to the hypothesised phylogenetic history of the genus. Although maple feeding is hypothesised to be the ancestral condition in the genus Paraclemensia, Rosaceae feeding (including Amelanchier) is hypothesised to be a derived capability of the P. acerifoliella species group.