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Hallowed 'Hex' hatch holds deeper meaning for some trout anglers

After fishing his way downstream on Wisconsin's Brule River, Duluth's David Zentner paddles back upstream. Zentner, a fly-fisher, often fishes the Brule for trout.1 / 2
A Hexagenia limbata mayfly rests on the surface of Wisconsin's Brule River. Forum News Service file photo2 / 2

Among fly fishers, the words are spoken with a kind of reverence.

"The Hex hatch."

Duluth fly-fisher Dave Zentner, 80, has been chasing the hatch for more than 50 years on rivers like Wisconsin's famed Brule and others. For him, the experience goes beyond the mere prospect of catching more or larger fish during this midsummer hatch. It represents an annual confirmation that all is right on these wild rivers.

The Hex hatch itself might stretch over 30 days, from early June into early July, depending on the river. It's the annual emergence and mating cycle of the Hexagenia limbata mayfly. Ardent anglers of trout across the Upper Midwest plan their pilgrimages for big brown and brook trout to coincide with the Hex hatch.

Other flies hatch from trout streams throughout the year, but the Hex hatch is a thing of glory, an event of magnificent proportions. The Hexagenia mayfly is among the largest and loveliest of mayflies, yellow-green with gossamer wings and a long, upswept tail. From bow to stern, the fly might stretch more than 2 inches.

Trout depend on this hatch even more than trout anglers do. The sheer biomass rising to the surface and taking flight is the single greatest feeding event in a northern trout's summer. Zentner says the hatch might contribute 20 percent to a fish's annual growth. Some put the figure even higher.

On muggy midsummer nights, at or well after dusk, the flies ascend from the stream bottom, shucking their larval cases as they rise. They emerge onto the surface, where they sit motionless on the water, drying their wings and preparing for take-off. They fly up and into the trees, go through one more life-cycle transformation, then mate in midair, dropping their eggs to the water.

"I love to think of it as a really important part of nature's aquatic rhythm," Zentner said. "It's almost like going to the symphony."

He takes the analogy further.

"You go, and the audience gets quiet," Zentner said. "Then the first violin walks in and tunes the symphony up a bit. It's like a couple of small trout chasing the first Hexes. Then the maestro comes out, and the baton goes down. Now you've got activity all over the river.

"It's such an incredible event. You're looking at water that looked like a desert, and now it's erupting. The fish are on it. It almost sounds like somebody dropping rocks in the river. Then — it's over."

For the angler, the Hex hatch represents a rare opportunity. Trout seem to lose all discretion during the hatch, feeding ravenously. Big fish that rarely show themselves for other hatches show up to gorge on this mayfly bonanza.

"It's not a technical thing," Zentner said. "The fish are insane. You don't have to make long casts. It's just being alive to witness this rush of life, the bountiful food, and one of nature's grand acts. For me, it never gets old. It's the size of the fish, the violence of the take, and what it means to the health of those animals."

Anglers stake out their territories early in the evening and wait to see if the hatch will come off. Some wade into the river. Others paddle or pole canoes quietly along shore to reach their favored pools. Before they fish, they stop and listen and wait. They look west, against the day's last light, to see if the big flies are coming off the water. The anticipation is palpable, magnified by the darkness, night sounds and an angler's imagination.

Zentner appreciates all that is happening on these muggy midsummer nights.

"It's the Milky Ways and the northern lights and the coyotes yipping and the deer blowing," Zentner said. "You're so full of adrenaline because of the environment you're in. The dew is so heavy. There are a million lightning bugs — all of that is wrapped into this thing."

How many of these hatches has Zentner seen? And still, it gets inside of him like this.

"The only difference between me at almost 81 and almost 31," he said, "is that I don't have, anymore, the need to catch a lot of fish. There are nights I don't even fish, or I'll take just one fish, and just pole or paddle the canoe for the guy up front."

He pauses for a moment.

"But what hasn't changed for me is the little-boy love to be there," Zentner said. "I feel cool about the planet. It's just a symbolic reassurance. It's such an important thing."

SAM COOK is a Duluth News Tribune columnist and outdoors writer. Reach him at (218) 723-5332 or Find his Facebook page at or his blog at