Blackfly occurrence was investigated on thirty plain streams of the low pla
in of the Friuli Venezia Giulia Region (NE Italy). Four species were found:
Simulium erythrocephalum, S. angustitarse, S. ornatum, and S. paraequinum.
Blackfly diffusion was larger than that reported in previous studies. Asso
ciations were found among Simuliidae species, hydrophyte species and water
velocity.