I've been asked by a couple of new fly fishermen to talk about dry flies, wet flies, and streamers. What makes it a certain type of fly, dry, wet, etc., how to tell what it is and when to use it.
Let me start by saying there have been volumes written about this very subject and what you read here will be a very basic abbreviated version. People have spent entire lifetimes on this subject and it's an area that as a fly fisherman, you'll never stop learning about.
Aquatic insects spend most of their life underwater. The fly fisherman will use imitations of these insects to fool the fish. some of these flies float and some sink depending on the stage of life the fly is imitating and the fish are feeding on at the time.
Mayflies have three stages; egg, nymph, adult (dun) and spinner. Mayfly eggs lay in the bottom of the stream. Over the course of a few weeks the eggs hatch into nymphs. The nymphs live under rocks or in the silt on the bottom of the stream for nearly a year. At the right time, often in the spring, the nymphs emerge, shedding their shucks and change into adults (or duns).
The duns leave the water and fly into the leaves alongside the stream where they molt and return in usually a day or two as spinners. The female spinners lay eggs on the water and then fall to the water and die. All mayfly duns have upright wings when riding on the water.
Spinners have airplane-type wings that lie flat on the water when dead or dying. Nymphs, emergers (the emerging nymph), duns, and spinners are all food for the trout. There are more than 700 different mayflies in North America in various sizes and colors. Fishermen and fish eagerly await their arrival each year.
Caddisflies are aquatic insects found in nearly all trout streams. They have four stages to their life cycle; egg, larva, pupa and adult. Female caddis lay eggs in clusters which hatch into larvae in two to four weeks. The larvae live underwater for nearly a year, part of this time in a case or shuck that they've made out of grit, sand, and bits of dead leaves. The larvae will enter a cocoon and become a pupa. After a couple weeks the pupa emerges just below the surface as adults.
These adults fly to the bushes and mate. The females return to the water to lay their eggs. Adults may live for awhile, but will eventually die after mating. Caddisflies look like small moths. They have antenna but no tail and are found in various shades of gray, tan, brown, olive, and black. Fish feed on all stages and flies are tied to imitate these stages.
Stoneflies prefer rocky fast moving, clear streams. Nymphs have two tails and two sets of wing pads. Stoneflies cling and crawl about on the stream bottom and feed on leaves, slime, and sometimes other insects. When it's time to emerge stoneflies crawl out onto dry land. After hatching they fly to bushes where they live from a few days to a few weeks. They mate here and the female returns to the water to deposit the eggs. Some stoneflies grow to 3 and 4 inches in length. Mayflies, stoneflies and caddisflies do not bit. We can handle them without worry to get a closer look.
Midges include the tiniest of insects and some that bit including mosquitoes and gnats. Midges have 3 stages; larva, pupa, and adult. Active year-round, they are sometimes the only insects available to the fish. Midges migrate and at times are in the surface film by the thousands. Not all midges are tiny buy most are. Midges are sometimes called the anglers curse because of their small size.
Terrestrials are a fun category of insects to imitate because it includes crickets, ants, grasshoppers, beetles, and all the land born insects. Terrestrials are fun to look at in your box, fun to fish with as they are often easy to see and fun to tie if you make our own flies. Many of these insects are around from the time the ground thaws to when it freezes again in the fall and often the fish are not as selective when fish terrestrials.
Flies On and In the Water
This illustration shows how various flies behave on or in the water. Dry flies float or rest on the surface. Examples would be adult aquatic insects (mayflies, caddisflies, etc.), terrestrials like grasshoppers and beetles and attractor flies like a Royal Wulff or an Adams. To keep the fly floating, use fly floatant.
Emergers rest just under the surface. Often when a fish takes an emerger it looks like he took a dry fly because he breaks the surface with his dorsal fin. If there is no tell tale bubble, he probably took an emerger. Emergers are often fished behind a dry fly as a dropper or trailer. The dry fly acts like a strike indicator and lets us know when the fish has eaten the emerger.
Nymphs, larva and pupa drift through the water with the current speed to imitate insects doing the same. Sometimes we 'twitch' the nymph to make it look alive. The fish will often take the fly as it swings around below us at the end of the drift. Some anglers like to trail these flies behind a dry fly with a section of monofilament or use a strike indicator. To make the fly sink, use split shot.
Streamers are fished underwater, sometimes deep, and retrieved or made to swim through the water. They imitate minnows, leeches, and crayfish and other things that the fish will eat. The fish will chase after the streamer – not wanting it to get away. Because the line is kept tight by retrieving, when the fish hits it will feel like a bump or smack often surprising the angler. To make the fly sink, use split shot. Sometimes they are tied so that the hook rides upside down and doesn't get snagged on the bottom of the stream.
For more examples of flies that imitate insects, take a look at the Umpqua Feather Merchants web site. That's where the examples above came from and it is incredible the number of fly patterns that are available to imitate the different insects, crustaceans, and smaller fish that big fish feed on! www.umpqua.com