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home Featured Articles Fly Fishing: What Is the Hatch Pattern and Why Should I Care?

Fly Fishing: What Is the Hatch Pattern and Why Should I Care?

If you had to guess about the most exciting part of fly fishing, what would you say? Some anglers would probably say the thrill of catching that big trout is the best part of a day of fishing. But more than likely, the average fly fisher finds the hatch pattern a lot more fascinating and exciting.

What is the hatch pattern? More importantly, why should you care? This article endeavors to answer these two questions in a way that new and inexperienced fly fishers can understand.


It Starts with Insects

An explanation of the hatch pattern begins with an understanding of how fly fishing works. Fly fishing is all about using artificial bait to mimic the actions of insects in and above the water. Getting the action right means landing a trophy fish nearly every time you go out. The different flies you can buy from companies like are designed to accurately simulate real insects in size, color, and shape.

The hatch pattern is important here because the kind of fish you are after as a fly fisher are not looking for bugs that descend from the air into the water. Rather, they are looking for bugs getting ready to leave the water for the first time. Fish are waiting for that moment when adult insects finally emerge to take flight.


The Hatch Misnomer

The hatch pattern is largely misunderstood by inexperienced anglers because use of the word ‘hatch’ is actually a misnomer. Entomologists use the word ‘hatch’ to describe that moment when the larval insect emerges from its egg. Yet that larval stage is not really what fish are after. They want adult insects.

To an angler, the hatch is not the moment larva emerges from an egg. Rather, it is the moment when a fully mature, adult insect finally emerges in preparation for flying away. The hatch to an angler is that moment when the transformation from nymph to adult is complete.


About That Pattern

Now that you have a basic understanding of how anglers define the hatch, we can address the hatch pattern. The hatch pattern is essentially the cycle that sets fish into a feeding frenzy. It begins with the pre-hatch.

Many species of insects that begin life as eggs under the surface of the water go through a pre-hatch phase that can begin hours or weeks before adult emergence. This phase is what transitions the insects from nymph to adult behavior. It is a phase with definite characteristics that fish have come to recognize.

For example, some species of insects begin a migration from the deepest parts of a river or stream toward the shoreline during the pre-hatch stage. Other species that don’t migrate may simply increase the amount of activity going on in the hours just prior to emergence. In either case, fish are waiting for the hatch just as anxiously as anglers are.

At the point adult insects are ready to emerge, they do so in one of three ways (patterns):


  • Terrestrial – The terrestrial hatch is observed when a mature nymph makes its way to the shore so that it can emerge as an adult insect on dry land. Nymphs that make it to the shore are not at risk of being eaten by fish, but fish will go after them as they travel.
  • Sub-Surface – The sub-surface hatch is one that occurs under water. The nymph emerges as an adult, then makes its way to the surface in preparation for flying away. Fish love the subsurface hatch for obvious reasons.
  • Surface – A surface hatch occurs when nymphs make their way to the surface long enough for their exoskeletons to peel away and the adults to emerge. Adult insects stay on the surface only a short time before flying away, as they are very vulnerable to fish.


The hatch pattern of any insect depends on its individual nature. Experienced fly fishermen and women learn about the various insects and hatch patterns related to their favorite fishing grounds. They will watch eagerly for the hatch to begin, then set about casting soon as adult insects start emerging.

If you are new to fly fishing, you should care about the hatch pattern because it will greatly affect your success as an angler. Learn it, know it, and love it. You can get more information along with expert advice and a free Braggin’ Rights Box of fishing gear when you sign up for a membership.




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