Dry Fly Angling - Part I

"In our family, there was no clear line between religion and fly fishing. We lived at the junction of great trout rivers in western Montana, and our father was a Presbyterian minister and a fly fisherman who tied his own flies and taught others. He told us about Christ's disciples being fishermen, and we were to assume, as my brother and I did, that all first-class fishermen on the Sea of Galilee were fly fishermen and that John, the favorite, was a dry-fly fisherman."

~Norman Maclean from A River Runs Through It

Dry fly fishermen are a special breed.  We endure rain, wind, cold weather, tree branches and strange looks from other anglers among many other things which would keep us off of the river and yet we persevere. The thrill of presenting a dry fly to a rising trout and having it dissapear in a boil of water is a singular event in the world of angling and once it is experienced it becomes a lifelong pursuit for many.  But a dry fly "purist" can spend a lot of time not catching anything.  Dry fly fishing is only effective when the fish are feeding at the surface and that is only about ten percent of the time.  Trout spend most of their lives feeding on the bottom and mid strata of the river and only feed at the surface when their is a hatch of aquatic insects like mayflies, caddis flies, stoneflies and the occasional terrestrial insect such as grasshoppers, beetles and ants when they are blown or fall into the water. 

Mayflies are the most common of the aquatic insects that trout eat so for the purpose of this article we will focus on them. 

The technical name for a mayfly is Ephemeridae.  This translates into the phrase, "lives but a day." Mayflies adults do not have mouthparts and therefore can't eat.  Their sole purpose is to procreate and then they die with the added bonus that trout find them delicious during every stage of their lives except the egg stage.

Another common name is Ephemeroptera, which translates to mean upturned wing.

The four stages of a mayflies' life cycle are; egg (ovum, 1 to 3 weeks), nymph (nymphal 11 months to 24 months with 20-30 moults), dun (sub-imago 1 to 4 days) and spinner (imago about 1 day). 

The mayfly life cycle starts with adult female depositing eggs in or on the water.  In some species the female will skim across the surface of the water in order to dislodge the eggs from her abdomen. Another species will fly across the waters surface and drop yellow or orange egg masses onto the waters surface. Some others will actually dive into the river in order to break the surface tension, then release their eggs underwater. Once the eggs are deposited in the water the exhausted insect, called a spinner, will fall onto the surface of the water where it dies and is often eaten by trout.

The eggs then fall slowly onto the lake or stream bottom and in time will develop into an aquatic creature called an immature nymph. These nymphs are classified into four basic groups: Burrowing, free-swimming, crawling and clinging. The Burrowing nymphs like areas that have a either slow or very calm current with a soft bottom made up of rich silt, fine sand, decayed organic debris and marl bottoms of pools, eddies and quiet stretches of river and streams, as well as, the firm bottom-muck of cool lakes and ponds. The free-swimming nymphs will inhabit areas where there is plenty of natural structure such as, aquatic vegetation and heavy aggregate bottom areas. Some fast swimming nymphs will also inhabit a riffled area. The Crawling nymphs will inhabit areas of moderate to fast current. Most species have weak legs and are very poor swimmers. They will inhabit the moderate currents among vegetation, gravel and the rubbled bottoms of the water column.

The process of aquatic insects rising towards the surface is called an emergence. Most anglers refer to this event as a hatch but the truth is that nymphs hatch from eggs and emerge from the water as duns. Every species has its' own emerging characteristics and time table. As the insects rise toward the surface, they become very vulnerable and fish will feed readily on them. During this emergence, fish will become very selective to the physical size, color, shape and actions of the emerging species.

Links to some hatch charts:

Orvis Eastern Hatch Chart

Orvis Western Hatch Chart

Once on the surface the newly emerged Mayflies will either remain in the waters current or attach itself to a partially submerged limb or rock in order to then separate themselves from their shucks - or exoskeleton, spread their wings, pump fluid into the veins causing the wing to strengthen in order to support flight. The Mayfly will float on the surface of the water, like little sailboats, with its newly inflated wings acting as sails being dried and blown around by the wind. This surface activity can last for a few seconds or a few minutes. Once the wings are dry and strong enough the insect will take flight. After taking flight, the sub-imago usually rests on the shoreline vegetation for 1 or 2 hours or 1 or 2 days depending on the species, while gradually going through the last molt and transforming from sub-imago into adult (imago or spinner).

These Mayflies can emerge like this by the thousands and is an experience that will be remembered by any angler encountering it for the first time. This is the Mayflies main defense against its natural predators, among them being fish and birds. They will hatch in such great numbers, condensed in both time and location, that predators are overwhelmed.

A good fly angler must determine what type of insect the trout are eating before he can make his first cast.  This is done through direct observation and querying the local fly shops and anglers.  Once you know what the fish want then you have to either purchase or tie an artificial fly that matches the size, color and form of the natural insect. 

There are two basic types of flies; those made to impress other fishermen and those made to impress the trout.  A fly can have characteristics which do both but the truth of the matter is that almost any fly can catch a fish depending on the circumstances but only the best tied fly will get oohs and aahs from your fellow anglers.

In part II we will get into casting techniques.