EN
The examinations were done from the middle of August to the end of September 1987 in randomely chosen apiaries situated in the Olsztyn voivodeship. A total number of 440 bee colonies was examined. Seventhy bee colonies were free of parasites (15.9%), in 217 (49.3%) only Varroa jacobsoni invasion was diagnosed, in 73 (16.6%) Varroa and Nosema apis invasion was found and in 80 (18.2%) of colonies only Nosema invasion was found. Extensiveness of Varroa invasion ranged from 0.1 to 100% but intensity and extensiveness of Nosema invasion was following: in 209 samples of bees from colonies parasitized by Varroa from 0.1 to 5.0% spores of N. apis were found in 61 samples (i.i. = 89 X 10⁵), in 61 sampels of bees parasitized by Varroa from 5.1 to 20% spores of N. apis were found in 13 samples (I.I. = 11—77 X 10⁵) and in the rest of the bee samples parasitized by V. jacobsoni from 25.1 to 100%. Nosema spores were found in 6 colonies (I.i. = 18—272 X 10⁵). The results point to a coexistence of V. jacobsoni and N. apis invasion in the examined apiaries. It is not possible to determine a close relathionship between N. apis invasion and V. jacobsoni infestation.