Irish Mayfly Dun

Materials Used;

Hook, Fulling Mill All-Pupose Medium size 10
Thread, Uni-8/0 Chartreuse
Tail, Dyed Olive Badger Hair or Grey Squirrel
Rib, Fulling Mill Pro Floss Flu-Yellow
Body and Thorax, Dyed Olive Rabbit
Wing, Dyed Deer Hair Dark and Light Olive

The Irish Mayfly Dun is a famous stage of one of the most important aquatic insects in fly fishing—especially in Ireland.
🪰 What it is
The Irish Mayfly Dun refers to the subimago (immature winged stage) of the mayfly species
→ Ephemera danica (often called the “Green Drake” in the UK & Ireland).
“Dun” = the stage when the mayfly first emerges from the water with dull, opaque wings.
🌍 Where it’s found
Particularly abundant in Irish limestone loughs such as:
Lough Corrib
Lough Mask
Lough Sheelin
These waters are world-famous for mayfly hatches.
⏳ Lifecycle (simplified)
Nymph (underwater, can live 1–2 years)
Dun (emerges, floats briefly on surface) ← this is the “Irish Mayfly Dun”
Spinner (fully mature adult that returns to mate)
🎣 Why anglers care
The dun stage is when trout feed aggressively on the surface.
It triggers the legendary Irish “Mayfly hatch” (usually May–June).
Fly anglers imitate it with patterns like:
Green Drake dries
Mayfly dun patterns