We document an established population of blacklegged ticks, Ixodes scapularis, on Corkscrew Island, Kenora District, Ontario, Canada. Primers of the outer surface protein A (OspA) gene, the flagellin (fla) gene, and the flagellin B (flaB) gene were used in the PCR assays to detect Borrelia burgdorferi sensu lato (.), the Lyme disease bacterium. In all, 60 (73%) of 82 adult I. scapularis, were infected with B. burgdorferi . As well, 6 (43%) of 14 unfed I. scapularis nymphs were positive for B. burgdorferi . An I. scapularis larva was also collected from a deer mouse, and several unfed larvae were gathered by flagging leaf litter. | Established population of blacklegged ticks with high infection prevalence for the lyme disease bacterium, Borrelia burgdorferi sensu lato, on Corkscrew Island, Kenora district, Ontario