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The Mayfly Nymph

  - Mayfly nymph (photo:

The wonderful insect that inspires all trout fly fisherman

Their names roll off the fly fisherman’s tongue like the names of lost loves. Making the angler drool almost as much as the fish (if fish could drool). Hendricksons, Green Drakes, Blue Wing Olive, Trico. If you are not in a state of Zen yet, remembering past fly fishing experiences, then you probably are not yet an avid trout fly fisherman.

For the novice, these are the common names given to various species of the hallowed mayfly. The mayfly is to trout fly fishing what the microchip is to the personal computer. Fly fishing never would have gotten off the ground if trout didn’t leap up and ingest the adult mayfly, in a perfect display of sleek efficient survival. This microcosm of the food chain has sparked fly fisherman’s imagination for generations, and has led to the explosion of the fly fishing experience that we see today.

But what about this insect called the mayfly. Let’s take a closer look at the entire class of insect. The mayfly is so worthy of imitation for fly fisher's because they are varied, they are prolific, and they live where ever trout live with few exceptions. They require the same living conditions as trout, relatively clean and cool water. They can vary in size to the tiny Trico down to size 24, all the way up to the giant Hexagenia that can go up to size 4.
Some can hatch virtually year around while others have a relatively specific and short hatch season. But despite all these variances there are some things we can learn about the species as a whole.  All mayflies begin their life cycle in the water, as nymphs. Now with the emphasis on keeping this simple, let me just break it down a little more. Nymphs can be classified in four distinct categories. They are: clingers, swimmers, burrowers, and crawlers.

  - March Brown nymph.  March browns are clingers. (photo:

Clingers are built broad and flat and like faster moving water. March Browns and Light Cahills fall into this category.  Their hatches are a little more sporadic, but they can still offer excellent dry fly action. Their emergence is relatively quick due to the nature of water they ware found.

 - Isonychia, commonly called a Mahogany.  The nymph is a swimmer.  (photo:

Swimmers like the Isonychias like pools, and slower runs and riffles. They are excellent swimmers, and strikes for them tend to be vicious. They can hatch heavily or sporadically.

 - Hendrickson nymph, a crawler  (photo:

Crawlers also prefer softer runs and riffles. These species such as the Hendrickson and Sulphur have the hardest time emerging from their shucks. Therefore, great fishing can be found drifting nymphs or emerger patterns just below the surface where fat fish love to slurp them up. Their hatches can be explosive and really send fish into a frenzy.
 - Hexagenia, a burrower and one of the larger mayflies.  (photo:
The burrowers like sandy or silt bottoms. They need the silt to burrow and survive. Their hatches tend to be legendary and very popular. These mayflies like the Drakes and Hexes, are large and infamous. The hatches can be very thick, but are often very short-lived.  Anglers mark their calendars around them.
 - This mayfly died during it's emergence.  It could also be called a cripple at this stage as it did not complete it's emergence.  (photo:

After the nymph stage comes the emerger stage, which we covered somewhat above. The emerger stage is relatively new are of concentration for the fly angler. But it has exploded in popularity, as this stage is the most vulnerable for the mayfly. Not yet an adult and no longer a nymph, they are very clumsy in the water and are free floating as they rise to the surface. Whole groups of patterns have been designed just for this window of a mayflies life.

For the novice fly fisher I hope this has given you a foundation for the appreciation you will sure grow to have of this class of insects. And for the ordained, now would be a good time to have your blood pressure checked. I will discuss the adult mayfly in a future article.