Based on the results of an extensive long-term entomofaunistic research of mayflies in Czechoslovakia, invasive behavioural patterns of some species are described. These species ca be characterized as follows, 1. vagile species with an apparent ecological adaptation (e.g. that of the genera Cloeon and Caenis), 2. submontane and montane opportune species (e.g. Baetis lutheri), 3. unspecialized, opportune widesprread species with a relatively wide ecological valency (e.g. Baetis rhodani, Ephemerella ignita). Man-influenced biotopes under study are represented by water reservoirs, ponds, man-made lakes, and lotic biotopes below dams after regulation of a stream bed or temporary exposure of heavy pollution. Since the EphemeropteraÅ› (and that of other aquatic insects in general) invasions increase the species diversity as well as the biomass of benthic organisms no special management of those biotopes is necessary.