The aim of the study was to determine species structure of aquatic bugs in four anthro-pogenic water reservoirs. Heteroptera structure observed in studied reservoirs was clearly differen-tiated, which refers to age of the ponds. Newly created water reservoirs become quickly colonized mainly by pioneering species Corixinae, which led to formation of taxonomic group population of density exceeding 2700 indiv. m-2. In older reservoirs there were fish, which potential predation pressure led to almost a complete decline of bugs. The reason of bugs poverty in water reservoirs colonized by fish was also probably a small habitat diversity, leading to lack of refuges from predators.