Given the progressive expansion of Dermacentor reticulatus, including its infiltration into urbanized biotopes, an attempt was made to verify a hypothesis on a change in this species’ habitat preferences. Studies were conducted in 2004 to 2008, chiefly during the period of the tick’s greatest activity. A total of 73 one-hour sessions of collecting were conducted in forests, meadows and wastelands of the Lublin region (Table 1). The marsh tick (also called the ornate cow tick) was found most regularly and in greatest numbers in open areas or young tree stands. Urban wastelands with a distinctly xerothermic character were found to be a particularly characteristic biotope (Table 2). This contradicts previous reports that wetland areas are its optimal habitat. Because this tick is a carrier of babesiosis and – probably – borreliosis (Lyme disease), the findings suggest an increased epidemiological threat right within city borders.