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Fly Fishing 101, Part 17

Mayfly Nymphs

There is a free magazine available at your local fly shops. Entirely supported by advertising (meaning free to you), Fly Fish America produces magazines for six regions of the U.S. (We get the Pacific edition.) One issue had a terrific article by Paul Marriner, titled the "Magic Inch." This magic inch is where insects are just prior to emerging in the top one inch of the water.

Nymphs along with spent spinners, empty shucks, and cripples who were not able to get out of their shucks all ride the current in this one inch layer.

Below the surface, more activity takes place. Some anglers claim 90% of the food trout eat is taken below the surface. That generally means nymphs.

Mayfly nymphs fall into four groups. A knowledge of which group is which will tell you which nymphs and adult mayflies you have in specific locals. Each of the mayfly families require certain environments.

Species which live in slow-water developed excellent swimming characterists. Other species evolved to crawl along the river or lake bottoms, cling to underwater rocks or structure in fast-moving water, or others which burrow in stream or lakebed mud.

Brown Drake
Brown Drake (Ephemera simulans)
Burrowing Nymphs
Burrowing nymphs construct protective burrows composed of fine gravels, sands, muds, or silts in river beds or lake beds.

Flav (Drunella flavilinea)
Crawler Nymphs
Crawler nymphs inhabit diverse habitats. Species in faster waters resemble clinger nymphs and species in slower waters resemble swimming nymphs.

Mayfly photographs by Jim Schollmeyer; from
Mayflies, An Anglers' Study of Trout Water Ephemoroptra
by Malcolm Knopp and Robert Cormier. Published by Greycliff.

Brown Dun
Brown Dun (Ameletus)
Swimming Nymphs
Swimming nymphs inhabit the widest range of habitats, from slow- to fast-flowing streams and rivers as well as ponds and lakes.
Pale Evening Dun
Pale Evening Dun (Heptagenia)
Clinger Nymphs
Clinger nymphs live in fast, even turbulent, waters. They have flat bodies that deflect water flow and strong legs for clinging to rock surfaces.

Looking at the four photographs, there are obvious differences between the nymphs. The differences are what you need to look for when buying or tying flies.

Now, how can you tell if there will be a hatch of mayflies? Or if there isn't a chance of a hatch because the water temperature is too cold what nymph to use?

In spring, water temperature needs to be in the low 40s. Peak hatches occur when the water temps hit 46 degrees and up. In summer, especially evenings, water temp needs to be in the 60 degree minimum. For fall mayflies, peak hatches will happen when the water temp is over 46 degrees.

Using a stream thermometer to check the water temp should let you know if there will be a hatch at any particular time. That is dependent obviously on knowing you have nymphs there. Finding the nymphs can be as easy as walking along a stream and reaching into the water and removing a small rock. Turn the rock over and see who is living on or under it. If it has the general characteristics of one or more of the nymphs shown in the photos, your chances are pretty good. You can hedge your odds even more if you check the nymphs for a little split towards the head on the insect.

This little split indicates that the wings are developed and ready. If there are no splits, you probably are stuck with fishing nymphs. Use a pattern that is as close to the shape, color and size of the nymphs you find.

Your casting does not have to be great to fish mayfly nymphs. Since it is a wet fly, a simple roll cast with an upstream mend will get your fly down to the proper depth.

I personally don't fish nymphs. Yes, there was a time when I did. As a kid I also fished worms.

Nymphing in America is sort of a chuck and duck thing for me, not as much fun as fooling a fish on a dry fly. Of course nymphs work. They catch trout and for some who must have a number count to have a successful day fishing, it may be the only way to fish.

Gold-Ribbed Hare's Ear, Bead Head Twist Nymph, Cream Variant Nymph, Hendrickson Nymph, Pheasant Tail Nymph, are just a few of the common mayfly nymph patterns.

Unfortunately, nymphing is misused. Numbers are not what fly fishing is about. The British do fish nymphs. Under very rigid rules. You only cast a nymph to a visable fish who is nymphing. Never when fish are rising, and only on designated waters.

As a fly fisher you will make many choices. Choosing to fish with a particular type of fly as in dry or nymphs is just one of those choices. Fly fishing is not carved in granite. You can always change your mind. The choice to fish nymphs is also yours ... as is the choice not to.

Stop by the Chat Room and meet some fellow anglers. It is a nice bunch of people - always willing to help new fly fishers! Or just share your fishing adventures. Fair skys and tight lines, ~ DB

Have a question? Email me!

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