This paper presents the results of observations on occurrence of Tetranychidae. During 1995-2001 investigations a total of 10 species, namely Bryobia praetiosa, Eotetranychus carpini, E. cary/i, E. pruni, E. tiliarum, Eurytetranychus buxi, Panonychus ulmi, Schizotetranychus schizopus, Tetranychus viennensis and T. urticae were collected in ornamental nurseries in Poland. The T. urticae was the most frequent species ofmites and it was found on 60 different species of plants belonging to 1 7 families. This species caused severe damage on Spiraea japonica (Rosaceae), Ulmus minor 'Jacqueline Hillier' (Ulmaceae), Magnolia spp. (Magnoliaceae), Buddleja davidii (Buddlejaceae), Sambucus nigra (Caprifoliaceae), Laburnum xwatererii (Fabaceae) and Daphne mezereum (Thymelaceae). Among ocher tetranychids, S. schizopus is also dangerous pest of grafted willows.