This is a fan wing mayfly with detached body.

It is made of copydex by dipping in and building up in layers
as a candel maker would around a core of microfibets.

Body: Detached body as above
Wing: Mallard breast dyed golden olive
Thorax: Lightly dubbed Fly-Rite
Hackle: Silver badger dyed golden olive over

Note: Copydex is a common latex-based rubber cement available in the U.K. (ELA)