---

There were hundreds, even thousands of those running on the ground in the leaf litter in the Bois de Lauzelle, Louvain la neuve (Belgium) this afternoon, April 21 2008. I take it the short-winged, big-eyed individuals are the males and the other ones the females of the same species (?)
They were quite unwilling to fly, but kept running busily and clumsily on the ground.
My first thought was Bibio marci, but they do not seem to have the typical front leg shape.
Size was approx. 8 and 10 mm respectively

Any suggestion ?
TIA
Philippe