The studies were carried out in Wielkopolska region (western Poland) in oat and winter rye cultures. Density and species structure of Thysanoptera were studied. Average density of adult Thysanoptera on oat reached 371.4 individuals/m², and was higher than on rye, where it reached 107.5 individuals/m². Limothrips cerealium Haliday was a dominant species on oat as well as on winter rye.