[Results of 20-year observations of changes in the size of an Ixodes ricinus (Acari: Ixodes) population and a change in its infection with tick-borne borreliosis pathogens in the north of the Kaluga Region].

The paper shows changes in the size of Ixodes ricinus ticks population and their infection according to the results of their 20-year systematic collections and censuses on the same routes in the Zhukovsky District, Kaluga Region. It has been established that there are always some infected I. ricinus ticks in the season of their activity (April to September). The maximal focal hazard characterized by the highest abundance indices for infected ticks is seen in May-June. This area requires greater attention due to the changes in the regime and borders of the buffer zone of the State Tarusa Complex, a national nature reserve.