Investigations were conducted in forest stands of the Beskid Śląski Mts. (BŚ) - the region affected by industrial emissions, mostly SO₂ and No_x and the Beskid Żywiecki Mts. (BŻ) - partly free of such emissions, in 1995 to 1997. In both these regions study plots were established at every 100 m in altitude from 700 m to 1200 m (BŚ) and 1300 m above sea level. In total 64 plots (30 in BŚ and 34 in BŻ) were established in stands mainly representing the mountain mixed and the mountain forest types. The investigation was undertaken with the following objectives: (1) to evaluate qualitatively and quantitatively the cono- and seminiphagous insects of Picea abies in selected localities of the B. Śląski Mts. and the B. Żywiecki Mts., (2) to assess the impact of these insect species on seed production, and (3) to identify the parasitoids of these pests.