When the big flies are on the water you need a pattern that ticks all the boxes. Heres a mayfly dun that gives a great footprint and is easy to tie.

Hook: Mustad C53S # 10-14
Thread: Cream
Tail: Moose body hair
Wing: Mallard flank
Body: Three moose mane hair one black two brown
Thorax: Cream dubbing
Hackle: Two furnace or badger hackles