Quick Tip: The Hex Hatch

By Scott Richmond

Big fish are attracted to big insects because they get a mouthful of nutrition with a minimum of effort. And big fish like the cover of darkness because it offers them safety. So what you do get when Hexagenia limbata --America's biggest mayfly--hatches at sunset? Hefty, greedy trout rising aggressively to take their food off the water's surface.

It's no wonder the "hex hatch" gets so many fly anglers excited. But the hatch also has its frustrations. Because the Hexagenias begin their emergence at sunset and continue to dimple the surface for an hour or so, most of the fishing is done in the dark. More than one fly angler has begun the hatch with enthusiasm and good cheer, and ended it in anger and cursing.

Here's a few tips that will improve your chances of catching fish, and that will diminish the likelihood of frustration.

  1. Anybody home? Hexagenias are persnickety bugs. They only live in a few stillwaters or slow-moving rivers, and if the weather isn't to their liking they just figure the hell with it and don't emerge in significant numbers. A cold spring and June can delay the hatch--maybe even put it off for the entire season. So before you pack up your hopes and your tackle, make a few phone calls to fly shops and resorts; find out if the bugs are really hatching this year.
  2. Start early. Many of the nymphs are active a couple of hours before they emerge. Take advantage of this by tying on a weighted nymph such as Burks Hexagenia ; use a floating line, a long leader, and a corkie-type indicator. Cast your fly and let it settle to near the bottom, then raise it up a couple of feet. Then let it settle back down. Use this lift-and-settle presentation until you've taken in enough line so you need to cast again. The indicator helps to keep the fly out of weeds, and it makes the "lift" more vertical, which is a better imitation of the natural insect's behavior.
  3. Be prepared. Take a headlamp (with fresh batteries!). Have a jacket or sweater to ward off the evening chill. Tie up several dry flies on leaders; use a loop-to-loop system to hook these up when your leader gets hopelessly tangled in the dark. (Tangles are not a possibility; they are a certainty.)
  4. Know when to switch. When the hatch starts, switch to a dry fly such as the Hexagenia Paradrake or an cripple-type pattern. Cast the fly and let it sit, then give it a few twitches, then sit, then twitch, etc. The natural insect makes a big fuss, so don't worry about moving the fly around.
  5. Use a heavy leader. It's a big fly, the trout are big, and it's too dark for the fish to see your leader. Give yourself an advantage and use a 1X or 2X leader. The heavier leader is also more resistant to tangling.

Scott Richmond is Westfly's creator and Executive Director. He is the author of eight books on Oregon fly fishing, including Fishing Oregon's Deschutes River (second edition).