Life cycle features of Ischnura elegans (Vander L.), Coenagrion puella (L.), C. scitulum (Ramb.) and Cercion lindeni (Sel.) populations in 2 small perennial ponds in homogeneous environments, 2 km apart, are compared on a monthly basis. Significant pond-dependent differences in respective phenology and mutual exclusion are hypothesized for i /. elegant and C. lindeni. Universita di Roma, Viale dell'Universita 32,