This is a medium-sized (wing length to 8mm), spring-flying Bibio with very milky-white wings in the male and uniformly dark wings in the female. Dwarf specimens of B. marci can superficially resemble leucopterus in the field, but leucopterus has a unique character in the almost equal-length spurs of the fore tibiae.

In woodlands and wetlands. 

The flight period usually peaks in May.

Bibio leucopterus is widespread and locally common, sometimes reaching impressive levels of abundance.

Status in Leicestershire and Rutland unknown, probably under recorded.