Description
Mayfly Nymphs – Life Below the Surface
Mayfly nymphs are the engine of the river and lake ecosystem. They are active year-round and represent a constant, reliable food source for trout and grayling from early spring to late autumn. To fish a mayfly nymph successfully, you must understand their behavior. They are categorized into three main types: Digging, Swimming, and Clinging nymphs, each adapted to specific environments.
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Digging Nymphs: Found in lakes and slow-moving river sections with soft or sandy bottoms. These include some of the giants, like the Green Drake (Ephemera danica).
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Swimming Nymphs: Agile and active, these are found in both still and moving water. They are often drift-feeders, like the Claret Dun (Leptophlebia).
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Clinging Nymphs: The "bodybuilders" of the mayfly world. Short, compact, and powerful, they live on rocks in the roughest currents, like the Yellow May Dun (Heptagenia).
Our Commitment: Anatomical Accuracy & Performance Since mayfly nymphs spend most of their lives tucked away near the bottom, they only become truly vulnerable when they lose their grip, drift to find food, or begin their journey to the surface to hatch. This is when the fish strike.
Our commitment is to provide imitations that match the specific silhouette and behavior of these three categories. By using J:son’s unique materials, we create nymphs with the correct proportions, lifelike legs, and balanced weight.
The Extreme Micro-Pattern – J:son Mayfly Nymph 5 Black (Hook #18) The Black Nymph 5 in size #18 is our smallest possible rendition of a swimming mayfly nymph. This "super-micro" pattern is designed for the most challenging fishing scenarios, matching the smallest members of the Baetidae family. In this size, the black coloration mimics tiny nymphs whose wing pads have turned dark just before emergence. It is a vital pattern for the late season or for clear, slow-moving spring creeks where fish have plenty of time to inspect your offering.
Tied on an ultra-delicate size #18 hook, this unweighted model offers an incredibly realistic, slow-drifting presentation. Even at this minute scale, J:son’s anatomical details—including the segmented body and lifelike leg profile—remain remarkably clear. The high-contrast black silhouette makes this tiny fly visible to fish even in complex currents or shaded water. When fish are "bulging" just under the surface or sipping tiny insects, this #18 nymph on a long, fine leader is often the only way to induce a take from a trophy trout or grayling.