Aim of the thesis was to evaluate the influence of environment on of life cycles attributes of stoneflies (Plecoptera) in Hron river. As a model groups Leuctra prima group and Leuctra fusca group were used. Diploma thesis deals with reconstruction of life cycles of those groups and with comparision of biomass, secondary production and growth rates between two studied localities Vaľkovňa and Beňuš. On the study site Vaľkovňa, total biomass of the both model groups was 6,1 times higher, and the production was 7 times higher than on Beňuš. Both groups showed univoltinne winter life cycles, differences have been recorded only in the timing of emergence. Growth rate of L. fusca group was comparable between the localities, while individuals of L. prima group grew faster in Vaľkovňa than Beňuš. Our observations suggest, that life cycles, emergency, growth rates, biomass and production of larvae was affected by the conditions of the environment, although an exact mechanism can not be deduced.