SECTION FOUR

The main families of insects that are important to flyfisherman are:

	Mayflies
	Caddis flies
	Stoneflies
	True flies (midges)
	Damsel and dragon flies
	Terresterials (ants, grasshoppers, ...)

A few things to keep in mind. Generally, the largest aquatic insect species will hatch during the higher stages of runoff (just remember, big water = big insects), and the smallest during the lowest water (such as mid-winter midge hatches). Large insects are probably simply too vulnerable during low clear water. Also, in tailwaters or spring creeks, where the water flow and temperature is more constant, the smaller insect species, especially midges, tend to dominate. Finally, after the growing stages, when an insect hatches from one stage to another, it usually drops in size. Thus, if you are killing them on a #16 nymph, and the fish start taking dries, try a #18 dry instead of a #16.

1. The Basic Lifecycle of an Aquatic Insect (mayfly, caddis, stone, midges)

The following stages are part of the aquatic insect lifecycle

	Egg - where all life starts :-), but unimportant
	Larva - the first stage after hatching. The insect is underwater and in some insect species this is a very important food stage for fish.
	Pupa - the second stage after hatching, but still immature. The insect is underwater still, and can be an important food source for fish. (Both the larva and pupa stages are referred to as "nymphs".)
	Subadult - the first adult stage, where the insect has "hatched" and is now out of the water and flying.
	Adult - the last adult stage, where the sole purpose of the insect is to find a mate, procreate, and lay eggs back in the water (and then die).

Not all insect species or families have all of the stages. The nymph stages must eat, and so they move around -- some a little, some a lot. Occasionally they goof and slip off into the flowing water, or get too far away from cover. This is when they are available to fish, and fish will gladly make a meal of them. The insect spends 99% of its time as a nymph, so even if relatively few nymphs become available, it is still alot.

When a pupal stage is ready to hatch into an adult stage, it must exit the water to do so. Different species do this different ways, but many just swim or drift up through the water column to the surface, and then ride the surface as they crawl out of the pupal case or "shuck". When insects do this en masse, flyfishermen call this a hatch and lose all sense of reason and time, and will ignore work, family, and everything else to be on the water fishing.

Finally, the adults need to deposit fertilized eggs back into the water. Some just poke their rears into the water while hovering, and release the eggs. Others swim down to the bottom. But, in general, they yet again make themselves available to feeding fish.

In terms of fishing, these different stages are fished differently:

	Nymph -- usually dead drifted deep along the bottom
	Hatching nymph -- several different ways: drifting shallow, even just below the surface (called an "emerger"), drifting deep and then lifting the fly (slowly) to the surface to imitate a swim up to the top, drifting at intermediate depths, and imparting some action, perhaps.
	Newly emerged adult -- classic dry-fly fishing, drifting a dry fly over rising fish (hopefully). Some species are active and you might impart action to the fly (i.e., skittering it across the surface)
	Egg-laying adult -- for surface-laying insects, classic dry-fly fishing with, perhaps, some action. For those that swim below, this is classic wet-fly fishing (a non-floating fly with a wing), drifting the fly and often fishing the "swing" -- where the line catches the current and swings down below you.

2. Mayflies.

The mayfly is the insect that trout fisherman generally think of when they think of insects. Its behavior generally makes it the most accessible to fish of all the insects, throughout its whole lifecycle. The larva stage is missing, and the immature mayfly nymph is entirely in the pupal stage.

The mayfly nymph has six legs distributed throughout its body, a tail of two or three short pieces, and relatively short antennae. It can be many sizes and colors, but predominantly one will find brown, size 12 to 18 nymphs. These nymphs are why a 16 or 14 gold-ribbed-hares-ear or pheasant-tail fly work so well so often. The nymph is generally all one color, with the upper back (the wingcase) being darker, even black, on the nymphs that are close to hatching age. Mayfly nymphs are either clingers or swimmers (some others may allow other categories). Clingers cling to the underside of rocks, and are more predominant in flowing water. Swimmers are more active, and may even have "fins" on their tail, and are more predominant in still waters (lakes).

When mayflies hatch, almost all species rise through the water column and provide classic hatch fishing, with emerger and dry flies. Adult mayflies have upright wings, thin bodies, long thin tails, and short antennae. Adult mayflies have two stages, the "dun" stage is the first and is often characterized by dull, opaque wings. The "spinner" stage is when the dun sheds its case (again), and generally has clearer, see-through wings (mottled in some species). It is the spinner stage that mates and lays eggs.

Many mayfly species swim below to lay eggs, and so offer wet-fly fishing. Many mayfly species also die immediately after mating, and offer "spinner falls" fishing, where the dying insects fall onto the water. These dead spinners have spread-out wings rather than upright wings, and so the patterns used to imitate them are different.

3. Caddis Flies (some are called sedges)

In the caddis family, the longest underwater stage is the larva, unlike the mayfly. A caddis larva essentially looks like a maggot, with a soft, often off-white body, usually a dark head, and with a couple of short short legs right behind the head that it uses to hold on to rocks with. Some caddis species have green, even bright green bodies, and are often called "green rockworms". In many caddis species the larva build cases out of sand, pebbles, sticks, and other debris, and the only thing that ever sticks out of the case is their head. Others are free-living. Both cased and non-cased caddis larva occasionally become loose and available to fish for food, and I'm sure they are softer and tastier than other nypmhs :-), so trout will often readily take a caddis larva pattern.

When ready to become an adult, the larva essentially coccoon themselves like moths or butterflies, and go through a pupal stage. During this time they are of no importance to fisherman. At the time of hatching, though, the pupa crawls out, and swims for the surface so it can hatch to an adult. This is a very important stage for fisherman, and emerger fishing in a caddis hatch can be very good. Caddis adults only have one stage. The adults have short bodies that are completely hidden (from above) by tent-shaped wings (not dome tents, but the old A-frame tents), no tails, and very long, pronounced antennae.

Caddis adults often skitter (or "motorboat") across the surface as they are drying and waiting to fly off -- even more often on lakes. In depositing eggs, most caddis species swim below the water, and so offer wet-fly imitation to be effective. They do not tend to die near or on the water, unless eaten by a fish, of course.

4. Stoneflies

Stone flies, like mayflies, do not have a larval stage but exist underwater in the pupal, or nymph stage most of the time. They also tend to be dark nymphs, have legs all through their body, and have short, stout, very visible tails and antennae. The most well-known and exciting stoneflies are the giant golden stones and california stones -- both found throughout the west. These giants are up to 2 inches long, and when available trout go nuts over them. However, there are many smaller species of stoneflies, and often the small ones hatch on warm days late in the winter.

Unlike mayflies, many stoneflies do not hatch by swimming to the surface, but crawl across the riverbed to the edge, where they crawl out to hatch. During this migration they often lose footing, and these times can provide excellent stonefly nymph fishing (deep, dead-drifting). There is only one adult stage, and eggs are laid by the adult dipping their rear end into the water and releasing eggs.

5. True flies (midges, chironomids, diptera)

Fisherman usually refer to true flies as midges, and although the common image of a midge is a size 20 or 24, nearly invisible fly, midges can get much larger, even up to size 10 or 12. As adults, they most often look like mosquitos, except without the stinging needle in front. Underwater, they spend a large portion of time in the larval stage, and look a lot like small worms during this time -- think of a thin short earthworm without the dark band. Colors will vary, but red is popular (often called a "bloodworm"), and is the basis for the highly effective "San Juan Worm" pattern and its variants. Midges are often found in tailwater environments -- they seem to thrive in the constant flow, constant temperature environment more than other insect types.

6. Damsel and dragon flies.

Damsels and dragons are most important in still waters, though they can be found in flowing water. The thin, bright blue or red "dragonflies" that you see flying over the surface of a pond are not dragonflies at all, but are damsel flies. The thicker, heavier, larger, and usually duller green or red "dragonflies" are in fact the real dragonflies.

In both species the nymph (pupal) stage is underwater, an active, carnivorous feeder, and is important in lake fishing. Both species crawl out of the waters edge to hatch, and so the actual hatch is not important to fishing. Like the adults, the damsel nymphs are thin while the dragon nymphs are stout. Both are fairly large, and can be imitated with size 10 and up to 4 or 6. Both are usually dull green to dark green, because they use weeds for cover. In weedless lakes, they could be brown.

Dragon nymphs have large prominent eyes. The nymphs should be fished deep, and with "hand-twist" (i.e., slow, short pulls) retrieves (as with all fishing, try other things, including faster, more active retrieves, if you're not catching anything). Some people fish blue damsel adult patterns as dries, cast to sighted fish. I have never done so, but they say the strike is amazing...

7. Terrestrials (ants, grasshoppers, beetles)

Obviously, terrestrial insects are not, as a matter of normal course, available to fish. But many do inhabit the land near the water, and will fall or get blown into the water, and thus become available as a food source. In the west, in summer, grasshoppers can be especially effective, fished near the bank, often cast extra hard so they splat down noisily. In other areas, ant patterns will often fool selective trout that have been seeing all the standard patterns being fished and have learned to avoid them. In the East, inchworms can be effective in forested streams. When it comes to terrestrials, you should, essentially, use your imagination.