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 Summer Evening Essential – J:son Mayfly Dun 4 Sulphur (Hook #22) When the summer sun starts to set and the water comes alive with small, yellow dots, the Sulphur Dun is the fly you need. This imitation is specifically designed to match the vibrant, pale-yellow hue of the Sulphur Mayfly (often species like Ephemerella invaria or smaller Heptageniidae). These hatches are famous for triggering intense feeding frenzies among selective trout.
Tied on an ultra-sharp size #22 hook, this micro-imitation captures the delicate profile of the natural insect. J:son’s signature foam body provides superior buoyancy, ensuring the fly rides high and dry even in the film. The realistic wing silhouette creates the perfect "footprint" that fish look for during a heavy hatch. If you’re fishing clear water on a warm evening and see yellow duns on the surface, the Sulphur #22 is your most reliable tool to fool the most cautious fish.