Blue Dun

The Blue Dun is a classic dry fly pattern designed to imitate various species of adult mayflies with bluish-gray or slate-colored bodies, particularly in the Baetidae and Ephemerellidae families. Common targets include Blue-Winged Olives and early-season duns. Its slender, dark body and upright wings give it a realistic profile for mayflies that hatch in cooler weather or overcast conditions. It’s typically fished during hatches in spring and fall on streams and rivers.

History:
The Blue Dun is one of the oldest known dry fly patterns, dating back to the 18th and 19th centuries in the British Isles. It became widely adopted in North America due to its versatility and effectiveness in matching a range of small gray mayflies. It has been tied in numerous variations—dry, wet, and soft hackle—with the dry fly version becoming a foundation pattern in classic fly-fishing literature. Its timeless silhouette and natural coloration continue to make it a staple in fly boxes today.