Troutnut Forum > Fly Hatch Talk > Hex nymph behavior
This topic is about the Mayfly Species Hexagenia limbata
It starts like a rise of small trout. There are dimples on the surface, little fingerlings eating midges, perhaps. But these are no fish. The water breaks and up pop the yellow sails of a giant Hexagenia dun, then another and another. A vortex appears in a flash below the mayfly and it vanishes in a slurp so loud it echoes off the distant bank. A square tail like a shark fin breaks the surface behind the swirl as a brown trout twice the size of your net turns back toward his deeper lair. The Hex hatch is on.
This Midwestern legend plays out every year on calm, dark, humid nights in early July. Anglers who only fly fish once a year drive hundreds of miles to play their part in the drama, while the mayflies themselves make the television news by showing up on doppler radar or calling snowplows out of dormancy to remove layers of Hexagenia duns from the bridges. In the cold trout rivers of Wisconsin and Michigan, huge nocturnal brown trout whose usual menu consists of smaller browns become, for a week or so, prime dry fly quarry.
These are the second largest mayflies in the United States, behind the related Litobrancha recurvata flies. Read more...
There are 20 more specimens...
The Discussion
| Millerpa | June 18th, 2006, 10:02 pm | |
| Michigan Posts: 2 | I have read in many places that the Hex nymph is a mud dweller. What does this mean? Does this mean they immediately change from egg to nymph and then burrow into the mud until emergence or do they simply burrow in the mud to find food and spend some time in the open water between meals? I have heard comments from fisherman that indicate they know the hatch has been happening when they see small holes in the muddy banks of the river. This is abit confusing to me. Could someone please clarify. | |
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| Troutnut | June 18th, 2006, 11:30 pm | |
| Fairbanks, AK Posts: 1113 | or do they simply burrow in the mud to find food and spend some time in the open water between meals? Close... it's actually kind of the opposite. Hex nymphs are nocturnal (as you might guess from their pale, light-sensitive bodies). They live in their burrows during the day and come out at night to forage around the stream bottom for food, by some reports. Others report that they only come out to molt, approximately once every 24 days, but when there are so many nymphs in the stream even this can make for good numbers. You can see the little holes in the mud at any time of year, but there is a common belief (and my very limited observations confirm it, for what they're worth) that those holes are much more noticeable around emergence time. I'm not sure how to reconcile this with what I've read about their nighttime behavior. So I guess I can't give you a perfect answer. But I can tell you for sure that they spend plenty of time outside of their burrows as nymphs. | |
| Jason Neuswanger The Troutnut | ||
| Millerpa | June 19th, 2006, 6:21 pm | |
| Michigan Posts: 2 | Thanks for info. Off to the steam. Hex is on! | |
| Taxon | June 26th, 2006, 5:06 pm | |
| Mercer Island, WA Posts: 478 | Millerpa- Couple things I'll add to Jason's great answer: Their burrow is a U-shaped tunnel; they are generally semi-voltine, meaning there is a new generation every two years, and of course, they are largest just prior to emergence, so would need the largest tunnel openings at that time. | |
| Roger Rohrbeck www.FlyfishingEntomology.com | ||
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