The Adams
The Adams is the dry fly you tie on when fish are rising and you don't know why - a grey, buggy silhouette that has covered every mayfly hatch on earth since 1922.
If dry-fly fishing allowed one pattern, the vote wouldn't be close: the Adams, Michigan-born in 1922, is the grey ghost that suggests EVERY adult mayfly without copying any - which is exactly why it works when you can't identify the hatch. More trout have risen to an Adams than to any dry fly in history.
What it imitates
A generic adult mayfly - grizzly-and-brown hackle, grey body, upright wings make a 'could be anything' silhouette that trout read as the bug they're already eating.
When & where it wins
Rising fish + uncertain hatch = Adams, anywhere on earth, all season. Match the SIZE of the naturals and the pattern covers the rest.
How to fish it
Dead-drift, drag-free, upstream to a riser: cast 1-2 m above the fish, let it ride the seam like a leaf. Drag - the fly skating unnaturally - is the only way to fish it wrong.
Sizes & variants
12-20 (carry 14, 16, 18 minimum); the Parachute Adams (see its profile) adds visibility, the Adams Irresistible floats rough water.
Tying notes
Classic Catskill tie: grey dubbing, grizzly+brown hackle mixed, grizzly hackle-tip wings. A beginner's third-or-fourth fly - the wings teach patience.
Common mistakes
Fishing it with drag (mend!), sizing by guess instead of matching the naturals, and rejecting it as 'too simple' while the angler next to you catches on it.