Description
The Mayfly Dun: The Moment of Truth (The Crucial Stage)
The stage of the newly hatched adult Mayfly is called the Dun. This is arguably the most critical phase for the fly angler. Depending on surrounding circumstances such as temperature, wind, and weather, the time it takes before the Dun is able to fly away from the surface will vary.
These newly hatched Mayflies are often an easy and vulnerable target for the fish, and many will end up in Mr. Brown Trout’s stomach. When the hatching is frequent, many fish species might become selective and only feed on Duns.
Our Commitment: Perfect Imitation
Our commitment is to provide imitations of the real insect where the fly has the right shape, size, proportions, and colours, and, not least, leaves the correct print on the surface of the water.
This imitation of an adult mayfly in the Dun stage possesses all the right proportions and properties. It looks natural, feels natural, and fish will eat it.
Our Large-Winged Dun Imitation Features:
- Correct Surface Print: The imitation creates the precise silhouette on the water film that triggers the selective fish.
- Optimal Vulnerability: Designed to mimic the wing-drying, vulnerable Mayfly just before take-off.
- High Quality: Exact proportions and colours perfectly match the natural insect.
Recommendations for Best Results
We do recommend you to use a J:son Swivel for all your fly fishing. However, it is necessary to use a J:son Swivel whenever you are fishing a J:son fly in size 1 or 2 to ensure perfect presentation and minimize line twist.
The All-Weather Essential – J:son Mayfly Dun 4 Olive Grey (Hook #22) The Olive Grey Dun in size #22 is a true workhorse in any fly box. This specific color blend is designed to match a wide range of small, olive-tinged mayflies, such as the Small Dark Olive (Baetis scambus/fuscatus) or late-season BWOs. These insects are notorious for hatching during "bad" weather—overcast skies, drizzle, and cool winds—making this fly your best friend when the conditions turn.
Tied on a fine size #22 hook, this imitation captures the subtle grey-olive hue of the natural dun’s body. J:son’s realistic foam construction provides the necessary buoyancy to stay afloat in choppy water or rain, while the delicate wing profile remains visible to both you and the fish. When you see steady rises on a grey day but can’t quite spot the insect, a small Olive Grey Dun is almost always the right choice to crack the code.