In the years 1999-2000 the occurrence oferiophyoids on grasses was studied in the Wielkopolska region. 9 eriophyoid species were recognized on 29 grass species. Eriophyoids were present in 38% examined plant samples. The most often infested were Agropyron repens and Lolium perenne and the least Arrhenatherum elatius. Abacarus hystrix and Aculodes mckenziei were the dominating eriophyoid species. The intensity of occurrence varied and was related to the eriophyoid species and the host plant. Feeding of some eriophyoids species caused either matting or browning or twisting of the leaf blades.

In the years 1999-2001 occurrence of eriophyoid mites (Eriophyoidea) and spider mites (Tetranychidae) on wild grasses growing in Wielkopolska region was investigated. Seven species of eriophyoid mites and three of spider mites were found on 24 grass species. Eriophyoid mites infested 38% and spider mites 57% of all examined samples. The most frequent inhabited grass species by eriophyoid mites were Agropyron repens and Lolium perenne, while by spider mites Dactylis glomerata and Bromus mollis.