Lamp-Lit Bridges as Dual Light-Traps for the Night-Swarming Mayfly, Ephoron virgo: Interaction of Polarized and Unpolarized Light Pollution
(A) Mass swarming of Ephoron virgo mayflies at night in Tahitótfalu (northern Hungary) at a bridge overarching the river Danube. (B) During the swarming we could observe that female mayflies performing their compensatory flight, flew up to the bridge-lamps. One part of females reaching the bridge landed on the asphalt road to oviposit, whereas the others joined to the swarm of several thousands individuals around the bridge-lamps. (C) With the progress of mass congregation the ovipositing females covered in greater and greater deal the asphalt road of the bridge. The mass of mayflies containing already perished and still ovipositing individuals formed large, extended, white stains. (D) The yellow egg batches are easy to recognise in the white crowd of mayflies, that consisted of several thousand eggs each.