Hex hatch draws anglers to the Brule River

Evening has enveloped Wisconsin's Brule River, and now the fishing has become mostly an exercise in listening. From just downstream come the liquid slurps that indicate trout are feeding.

Hexagenia limbata mayfly
A Hexagenia limbata mayfly rests on the surface of the Brule River. (Sam Cook /

Evening has enveloped Wisconsin’s  Brule River, and now the fishing has become mostly an exercise in listening. From just downstream come the liquid slurps that indicate trout are feeding.
A trout has risen to suck down a spent mayfly.
“That’s a good fish,” says Steve Therrien, a longtime Brule River fly-fishing guide.
His voice comes softly in the darkness from the stern of the canoe.
“I know,” says his friend and veteran Brule guide Tom Heffernan of Port Wing.
Heffernan is in the bow, casting a dry fly called a Neally’s brown drake. The two guides have come to the river on this late June evening to see if the fabled Hexagenia mayfly hatch is happening. Therrien, in the deepening twilight, can just make out some big flies against the wall of a nearby boathouse.
“I think we’re looking at Hex spinners,” Therrien says.
Spinners are Hexagenia females, spent from mid-air mating, falling back to the water. They’re as big as small dragonflies and defenseless, their wings plastered flat on the river’s surface.
For the trout, the Hex hatch is the main event of summer, a slurpfest, a protein windfall. Reclusive brown trout, including the big boys, turn out to feed with gusto on these meaty morsels.
Fly fishers drive hundreds of miles to the Brule and other northern Wisconsin rivers, hoping to take advantage of the big browns that have abandoned their caution. For those who know the Brule and its rich history, the Hex hatch is a homecoming.
“Everyone has their favorite spots. It’s this community of people,” Heffernan had said earlier that evening, as we waited for steaks and beans to cook over a small fire.
How good is it? Presidents Grover Cleveland, Calvin Coolidge, Herbert Hoover and Dwight Eisenhower all spent time on the Brule. Coolidge spent the summer of 1928 at Cedar Island on the river.
The Hex hatch is the focal point of an angling summer on the river, and the hatch is vital to the river’s resident trout.
“It’s probably the biggest protein mass to hit the river all summer,” Therrien said.
Therrien has been guiding on the river since 1978, Heffernan since 1980. With their clients, they do a little brook trout fishing in the late afternoons, have a quiet dinner on the river, then move downstream by canoe at dusk. That’s when the Hex hatch will come off, if it’s going to happen, and when the trout come out to feed.
Sound of success
Now comes an implosive sucking sound from downstream. Heffernan raises his fly rod and sets the hook. Splashing ensues in the darkness. Heffernan strips line quickly, bringing in the fish. It’s a German brown trout, handsome if not hefty in the beam of Heffernan’s light. He reaches for his brown drake, plucks it from the fish’s jaw and inspects the trout, its gold flanks splashed with red and brown spots. He slips it back into the river.
Heffernan and Therrien triangulate the slurping. Heffernan delivers his delicate offering.
Despite the frenzy of feeding that the hatch inspires, it also can be confounding to anglers. If duns (adults) are emerging on the water and spinners are falling from the sky and maybe some brown drakes are emerging with them, it can be hard for a fly fisher to determine just what the fish are taking.
“It can be one of the most frustrating hatches on the planet,” Heffernan said. “But when you hit it right, they’re rising right next to your boat. They have no fear. You can fish a stretch of the river for years and not think there are any big fish there. But during the Hex hatch, you realize they’re there and they’ve been there all along. They just don’t show themselves.”
Typically, the hatch occurs sometime between mid-June and July 10, Therrien and Heffernan said.
“Historically, the Fourth of July you’re almost guaranteed to hit it,” Heffernan said. “But some years, it’s over.”
Wet world
Rain has been falling lightly along with the Hex spinners. Falling on the bright blue forget-me-nots. Falling on the grandfather cedars that reach out over the river. Falling on the blue-flag iris along the shore.
Now the world seems completely wet. River below, rain above, the luscious slurping all around. Hatch or no hatch, the Brule is a wonderful place to be on a post-solstice night in June. What one hears is the dipping of Therrien’s paddle, a green frog belching, a set of riffles just upstream, the whisper of Heffernan’s fly line in the air overhead. The air is heavy with the aroma of June. The mosquitoes and no-see-ums also seem to think it’s a good night for feeding.
A significant slurp issues from downstream, and Heffernan’s fly is fast to the lip of another brown. He plays it quickly to the boat. It’s a beauty, maybe 15 inches long, a handful, gleaming in the light of the headlamp. It, too, is given back to the river.
And that is it. The spinner fall dwindles. The slurps subside. The rain picks up.
There’s a dock waiting for us downstream, and a cabin with a light in the window.

The lifecycle of the Hexagenia mayfly
The fabled Hexagenia limbata mayfly is the second-largest in the country. (The largest, found primarily in Michigan streams, is the Litobrancha recurvata.) In northern Wisconsin streams, the Hex hatch can happen from mid-June to about July 10.
According to Craig Macadam, writing for the Freshwater Blog, a mayfly’s life cycle starts with the males forming a swarm above the water and the females flying into the swarm to mate.
“After copulation,” Macadam writes, “the male releases the female, which then descends to the surface of the water where she lays her eggs. Once mated she will fall, spent, onto the water surface to lie motionless, with her wings flat on the surface, where fish pick them off at their leisure. The male fly rarely returns to the water but instead he goes off to die on the nearby land.”
On the stream bottom, eggs attach to plants or stones, according to Macadam. The nymphs take anything between a few days to a number of weeks to hatch depending on water conditions and the species. The resultant nymphs will spend various lengths of time, up to two years, foraging on the bottom before emerging as an adult fly, Macadam writes.
When it is time to emerge, the nymphs make their way to the surface where they pull themselves free of their nymphal shuck and emerge on the surface.
The Hex emergence begins at twilight and is most intense then, but it often continues to provide fishable action for hours, even past midnight.
Fly fishers sometimes use flies that imitate the freshly emerged Hex flies sitting on the water’s surface, and sometimes use flies that imitate the spent females that have fallen to the water after mating. Anglers use the term “spinner fall” to describe an event in which spent females are falling back to the water.

Related Topics: FISHING
Sam Cook is a freelance writer for the News Tribune. Reach him at or find his Facebook page at
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