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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington
This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Mayfly Genus Hexagenia

These are huge mayflies. Hexagenia limbata, by far the most important species, is the second largest mayfly in the United States. The largest is its close relative, Litobrancha recurvata, which until recently was also in the genus Hexagenia.

Two minor species, Hexagenia atrocaudata and Hexagenia rigida, may be noticed later in the season than limbata.

Read each species page for emergence and other details.

Where & when

In 266 records from GBIF, adults of this genus have mostly been collected during June (29%), July (28%), August (22%), September (11%), and May (7%).

In 125 records from GBIF, this genus has been collected at elevations ranging from 3 to 11102 ft, with an average (median) of 3051 ft.

Genus Range

Specimens of the Mayfly Genus Hexagenia

4 Male Duns
8 Female Duns
6 Male Spinners
2 Female Spinners
13 Nymphs

4 Streamside Pictures of Hexagenia Mayflies:

1 Underwater Picture of Hexagenia Mayflies:

Discussions of Hexagenia

Hex hatch water temperature range?
4 replies
Posted by NEMatt on May 23, 2014 in the species Hexagenia limbata
Last reply on Jul 5, 2016 by Bombillo

New to the site - love it. I was wondering if there was a suggested range of water temperature at which the Hex likes to hatch.

What is the big DEAL about the HEX?
21 replies
Posted by Spinner on Jun 21, 2006 in the species Hexagenia limbata
Last reply on Jul 5, 2016 by Bombillo
fishing in the dark.......
stepping in holes?

I hate the dark........

I don't need the hex........

Mayfly larvae -wigglers preservation as bait
20 replies
Posted by Teacherprea on Jun 2, 2007 in the species Hexagenia limbata
Last reply on Apr 29, 2014 by TNEAL
I am a fly fisherman but not a "purist". A friend of mine has a place on the UP of Michigan. He just called me and said a guy told him there is a way to preserve "wigglers." They use them alot up north, those that are not fly fishermen or ladies. They are fishing perch, bluegill and crappie. He heard there is a way to "blanch" them.Drop them in hot water for a few minutes and they turn rubbery. They then will keep indefinitely. Has anyone heard of this? If so, how close to correct is the procedure I mentioned??
Thanks for anyone's help.
Hex Hatch 2012
5 replies
Posted by Hdhungryman on Apr 15, 2012
Last reply on Aug 12, 2012 by Taxon
Forget the end of the world. The Hex Hatch is just about on again. For more than 7 years now, I have been making the journey north and have encountered one of the most prolific hex hatches I have ever seen (in the West that is). We all know that there are very specific conditions that must exist in order for this amazing event to occur. There are a few notable locations though I have found Henderson Springs in Big Bend, CA to be the most exciting from the perspective of a flyfisherman.

I am constantly keeping an eye out for when the hatch starts in this region. I will do my best to keep my post current as I get further updates. Make it a great season!

Hexagenia orlando
4 replies
Posted by Curtis on Feb 29, 2008
Last reply on Mar 1, 2011 by Jmd123
Does anyone have any hatch dates for hexagenia orlando in the Central Florida area? Several lakes near me have populations and I am gathering data. I have photos and one hatch record.

Start a Discussion of Hexagenia

Mayfly Genus Hexagenia

Genus Range
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