Population dynamics of larval stages of Tauriphila risi Martin and Erythemis attala (Selys) in Punta Lara gallery forest, Buenos Aires, Argentina (Anisoptera: Libellulidae)

Larval populations of the 2 spp. were studied in a lentic freshwater environment. 13 larval instars were recognized from plots of head width and length of wing-pads. Density, population dynamics, age structure, flying period and winter quiescence were analysed. Both uni- and semivoltine individuals were found. Microhabitat differences were found between the 2 spp, T. risi preferring Pistia stratiotes and Hydrocotyle ranunculoides, whereas E. attala preferred lemnaceas. A life table was constructed for T. risi, which showed mortality rate maxima at hatching and at 10 and 23 months.