One of the oldest trout fly patterns in existence, the Alder wet fly is at least as old as Dame Juliana Berners historic book “A Treatyse of Fysshynge Wyth an Angle” published in 1496. This version called the Bloody Alder is similar in profile but with a red tag and head.
Hook: #10-20 standard wet fly
Body: Peacock herl
Hackle: Dark hen soft hackle
Wing: Pheasant tail fibers
This fly can be found in The Federation of Fly Fishers,
Fly Pattern Encyclopedia: https://amzn.to/34U0rUe