Photo notes: Above: a male, Upshur County, West Virginia. Despite the family's common name of March flies, this species is more common in fall, and was photographed in November.
Middle photo: same time and place. Bibio longipes has pale-colored hairs. Note the division of the eye into an upper lobe and a lower lobe, typical of male March Flies.
Lower photo: An apical spur on the foretibia (variously shaped) is present in members of the genus Bibio.
American Insects site