Nymphs

The nymph is an artificial representation of an insect's aquatic larvae or pupae stage of it's development. It's been said that between 80% to 95% of the trout's diet consists  of these invertebrates, so it only stands to reason, that if you want to catch fish, you should be keenly aware of the various forms and functions of the nymph. 

Since the nymph is in a transitional stage from egg to adult, they will be found in all layers of the water table. They can be fished from the surface film to imitate adult emergers and stillborn flies or they can be bumped along the bottom to imitate the un-hatched larvae and everywhere in between as they are completing their life cycle. Finding the stage and depth that the trout is feeding  can be obtained through weighting the fly while creating the fly; or by adding various weight of split shot while fishing.  

There are literally thousands of nymph patterns, all of which are designed to be the "better mouse-trap." In actuality, size, color and presentation will be the dictating rule to landing fish especially in high or discolored water or on very sunny days.  All fish are opportunistic. So if a fly that's "buggy" that passes through the zone the fish is holding in, he will be more likely to eat it rather than expend the energy to search on the surface. This is why so many effective fisherman now utilize the dry and dropper set-up.  It allows them to fish subsurface where most feeding occurs and yet also present an alternate food source on the surface.

"A general survey of the circumstances, stages, and conditions in which the insects which serve the trout as food may be preferably simulated or represented may not be amiss."
~G.E.M. Skues
 

Gold Ribbed Hare's Ear

Nymph Proportions

The Tail (T), while not in every nymph recipe, should extend from 1/3 to 3/4 the Shaft length. The Abdomen (A) is normally 2/3 the hook length or 2 times  the hook gape and should be tapered --- smaller at the rear to larger at the wing --- to simulate a natural insect's abdomen. The Rib, though not in every recipe, can vary from 3 to 10 spiral wraps and varies with the length of the hook Shaft. If tying a direct imitation, you should tie in the same number of segments as the natural.   The Thorax (T) makes up the remaining 1/3 of the hook shank, leaving enough room next to the eye to form a small Head and finish to the fly. The Wing, often used in emergers, in most cases should be 1 to 1 1/4 times the body length.  Sometimes Hackle or Feather barbules are used to simulate  legs,  should be 1 1/2 times the Hook Gape (G). Other synthetic materials may be used to imitate legs and should be sized in proportion to the pattern.  Likewise, some patterns call for Antennae and should be tied in with relative proportion to the natural.   Wing cases, typically are tied over the Thorax, while other types of patterns have Shellbacks that cover the entire length of the flies Body length.

As mentioned in the previous section on Hooks, you will find more variety Nymph hooks than any other type of hook due to the wider variety of shapes and sizes of the many different species of invertebrates.  Different manufacturers have their own nomenclature for different uses. Nymphs can have a curved or a straight shank, depending on their intended use.  Nymph hooks are typically a heavier gauge than a dry fly hook, which enables them to sink below the surface. Hook length is dictated by the profile of the insect that you are trying to create. Again, most recipes will designate, size, type and length. All manufacturers will have similar hooks so it will be up to you to decide your preference. As previously referenced, hooks come in all sizes but generally, for most nymph patterns, hooks will range in size from 4 to size 26.  Some patterns, especially midge patterns, may go down to size 32, while some larger terrestrials or giant stoneflies may go up to size 1 or 2.

Mustad 3906 - Nymph Hook