Phantom Crane Flies
This common name refers to only one family.
These are pretty much always called Phantom Crane Flies.
for details about craneflies. This family is not known to differ from them in any ways important to anglers except appearance.
This family has evolved a really unusual feature for an insect: its legs also serve the function of wings. The tibiae (Tibia: A middle segments in the leg of an insect, located between the femur and the tarsus.)
are greatly enlarged and help catch the wind. The legs usually have white tips, making them very easily identifiable in flight. There is a ghostly look to a dark, sparse insect flying around the stream, usually alone, with the fixed bright white points of its leg tips surrounding it like a halo.