The authors compared the species composition of aquatic insects in the
streams and rivers of the Small Carpathians and Zahorie region (the M
orava river basin). They discovered considerable differences in the se
ttlement of these regions caused by their different physiographic char
acteristics. For assessment of sozological localities significance a b
iosozology index was suggested. With respect to the occurrence of most
endangered, vulnerable, and rare species the middle part of the river
Rudava appears to be most valuable. The occurrence of the following s
pecies has been confirmed there: Heptagenia flava, Brachycercus harris
ellus (Ephemeroptera), Taeniopteryx nebulosa, Periodes dispar, Isopten
a serricornis (Plecoptera), Aphelocheirus aestivalis (Heteroptera), Di
xa nubilipennis, Dixa nebulosa, Atherix ibis (Diptera). The authors re
commended very strict preservation measures particularly in this regio
n.