Emergers, the Controversy

I believe in the concept that says, trout prefer eating the emerger fly over that of the dry fly. This concept does not say trout will not eat a dry fly, trout do, it simply says they prefer eating the emerger fly. As for me, this concept over the decades has played out to be simply the truth. Do not get me wrong I have caught plenty of trout on adult dry flies during this time. I have just caught more trout using an emerger fly pattern than I have using an adult fly pattern.

The science of what an emerger is simple. It can be defined as: An aquatic insect that leaves the bottom of a river to swim to the surface to become a winged adult. No fly angler can question this, it is a simple defined fact. The emerger phase of an aquatic insect’s life cycle is unquestioned. Some folks like to argue facts but to argue the validity of this fact would be borderline hilarious and no sane angler would attempt to do so.

The logic of why trout prefer eating emergent aquatic insects floating in or just below the meniscus over that of a just emerged adult fly is also un-questioned in most fly fishing circles. Trout see extremely well underwater. All emergent aquatic insects stop their journey through the water column at the meniscus or surface film. Here they become trapped until they can finally break the water tension and free themselves from the surface. This takes time. Meanwhile they are trapped at the surface, moving at the speed of the current right in front of a hungry trout. These bugs become easy food for trout mainly because they are trapped, moving to feeding trout, trout SEE them easily, and the emergent bugs become easy to eat.

Whereas a newly emerged adult aquatic insect who is just sitting on the surface is no longer a water breathing insect. It is now part of the air breathing world. This dilemma is the root of the issue. Trout see really good under water. Above water, in the air, their vision is blurry at best. Similar to our vision underwater without a face mask. In the case of the mayfly, this newly hatched insect must remain on the water’s surface for a significant period of time until it can fly away.

 Here even if a trout could see the insect it would appear blurry at best. You also have to factor in the fact that this bug is sitting on a mirror which a trout cannot see through. Humans look down on water and see right through the water to the bottom. Trout looking up cannot see through the meniscus. The surface to a trout looks like a mirror in the distance. So now you have a newly hatched adult, say a mayfly dun, which is in the air breathing world that  trout cannot see very well in, sitting on a mirror which trout cannot see through that may or may not be there when it gets near a feeding trout.

To sum up the difference between an emergent aquatic insect and a hatched adult is simple. Trout can see an emergent aquatic insect clearly and they cannot see the hatched adult. Well that pretty much sums up what an emerger is and how much trout love them. There is an old saying in trout fishing, “Trout are lazy and will spend the least amount of effort to achieve a goal”. This old saying’s logic is certainly true when it comes to trout feeding at the surface.

Okay you might say but what about the controversy you listed in the title to this little piece? Well that is an appropriate question. I wrote about the science of emergers being unquestioned and I wrote about the logic behind why trout prefer eating the emergent aquatic insect over that of the hatched adult. But for me to discuss the controversy of emergers we first have to understand what is not controversial about emergers. That now stated let me begin to explain the controversy in emerger fishing.

The controversy is not in the science of what an emerger is or the logic in why trout prefer to eat them over the hatched adult. The controversy is centered around what is an emerger artificial fly and what is a dry fly. This can be confusing because an emerger is classified as a dry fly.  Not only is the emerger artificial fly considered to be a dry fly, the mythological, all seeing dry fly guru who is in charge of all things fly fishing has further classified an emerger artificial fly as an imitative fly.

A friend comes by the shop and says hi to me. I reply kindly and ask if he has been fly fishing lately. His reply is he just got off the Owyhee River and just landed 20 large brown trout. I ask him how he caught them, and he replies, “On a dry fly”. I go further and ask him what dry fly he used to catch them. He goes on to tell me he caught all his trout on Pale Morning Dun Parachute. I ask to see some pictures and we enjoy the pictures and stories together.

Later after he leaves another friend comes by the shop and tells me the same story. He too caught 20 trout on the Owyhee River. When I asked him what fly he used to catch them on he replied, “On an emerger”. When I ask him what emerger pattern he used to slay all those trout his reply is the same, “A Pale Morning Dun Parachute.

Here we have 2 anglers fly fishing the Owyhee River, on the same day. Both anglers caught 20 trout each and both anglers caught them on the same fly. Who is right and who is wrong. Well these guys are friends, and I am not going to correct one of them. However, the one who caught all his trout on a Pale Morning Dun Mayfly Parachute Emerger got it right. There is your controversy. This is just the tip of the iceberg. There of course are hundreds of dry flies to choose from. Which one of these is a dry fly and which one is the emerger dry fly? How can a nymph ever be considered an emerger let alone a dry fly.

To better understand the whole concept of emergers you first have to begin at what defines an emerger. An emerger is an aquatic insect that leaves the bottom to swim to the surface to become a winged adult. Few can argue with this science. This is a clearly defined statement on a certain stage of an aquatic insect’s cycle of life. However, how does this carry over to the artificial fly we use to imitate this phase of the insect’s life?

Well there is a definition that may help us to understand what is considered an emerger artificial fly and what is considered a dry fly. Let’s not lose track that an emerger artificial fly is considered a dry fly and what we are defining is really what is an emerger artificial fly and what is an ADULT artificial fly. An emerger artificial fly is a fly when its body is either under, in or on the meniscus (Surface film). An adult artificial dry fly is when the body of the fly is neither under, in, or on the meniscus. The body of an adult artificial dry fly is off the meniscus. Those that agree with the definition can begin to match the right “Dry fly” to the hatch going on in front of them. Those who disagree will continue to catch their trout on dry flies regardless of the pattern they are using. No harm done. Well yes or perhaps no. Either way this can open a whole new can of worms that I will save for another time.

Experience has taught me there is not anything I can say that will change an angler’s view of what a dry fly is, so I do not try. Nor do I feel compelled to involve myself into the controversy. Age and experience has taught me to pick my battles, so I think I’ll just let this one go on brewing. Both anglers were successful and happy about their trip to the river. Let’s just leave it at that.

Mike Sandifer