Larval development and ecology of Baetis liebenauae Keffermüller (Ephemeroptera : Baetidae) in a north Italian lowland spring

The life cycle of Baetis liebenauae has been investigated in a lowland spring of Northern Italy that shows a relative stability
of water temperature. Nine postlarvula morphological stages of the larva were identified and a «jump development» of the wingpads
between stage pairs has been noted. B. liebenauae is here a typical polyvoltine species and three generations can be defined,
with the late-summer/autumn generation being the main one. During this generation the species is often the dominant taxon
of the benthic community and shows a high larval density. Marquet differences have been in comparison noted with the development
of this species in Poland. This is probably due to the different thermal features of the two regions. A temporal shift of
the main generations seems to allow the coexistence of B. liebenauae and other high density Baetidae species. In Southern
Europe the species is typical of small lowland streams with slow flowing waters. Its larvae live on aquatic macrophytes and their
presence on mineral substrata can be considered as occasional.