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Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large Brown Trout that only touch streamers for the rest of the year.

Mayfly Genus Heptagenia

Although still an important genus in its own right, Heptagenia no longer includes many of the key hatches it used to. Several important species have been moved to its sister genera Nixe, Leucrocuta, and Ecdyonurus.

Of the remaining species, the best hatches come from Heptagenia elegantula in the West. The genus is generally unimportant in the East and Midwest, where the most likely species to produce fishable hatches is Heptagenia pulla.

Hatching behavior

Heptagenia nymphs emerge very quickly, so emerger patterns are unimportant. The duns may or may not float long enough to get trout excited.

Spinner behavior

Spinner falls give the most promising action produced by Heptagenia species.

Specimens of the Mayfly Genus Heptagenia

5 Nymphs
1 Male Dun
Male Heptagenia culacantha  Mayfly Dun
Hyun Kounne generously provided photos of the striking, hard-to-find Heptagenia culacantha from the mainstem Delaware River. She mentioned it was one of maybe half a dozen she saw on the water that day.
1 Adult
Heptagenia solitaria (Gray Fox) Mayfly Adult
This species is common in the Flathead River below Kerr Day. The river here is fairly warm with a cobble and boulder bottom with heavy periphyton at times. This species is not common elsewhere in western Montana.
4 Male Spinners

Recent Discussions of Heptagenia

Added more Heptagenia culacantha info
12 replies
Posted by Troutnut on Dec 19, 2006 in the species Heptagenia culacantha
Last reply on Feb 8, 2012 by Entoman
I went to the entomology library today and photocopied the 1985 paper that first described this curious species. I've updated the culacantha page with this information.
Link to pictures of H. culacantha
2 replies
Posted by Troutnut on Oct 20, 2006 in the species Heptagenia culacantha
Last reply on Oct 4, 2007 by Troutnut
Many thanks to user Softhackle for digging up this link. I knew about the thread from back when it started, but I wasn't able to find it when I went back to look last night. Good work!

Fly Fisherman Magazine forum topic with two pictures of a H. culacantha dun.

I've added the species to the "live" part of the database and put up a rudimentary page where I can compile any more information we find.
Does anyone know anything about Heptagenia culacantha?
8 replies
Posted by GONZO on Oct 19, 2006 in the species Heptagenia culacantha
Last reply on Apr 18, 2007 by Konchu
This is a shot in the dark, but I'm trying to track down descriptive information about a rather rare "mystery mayfly." Heptagenia culacantha was identified in 1985 (Evans, Botts, & Flowers). About all I have right now is a tease from the Journal of the New York Entomological Society--"This infrequently taken species, one of the largest and most striking North American heptageniids, is known only from Pennsylvania and New York."

The reason I'm so interested is that I believe I encounter a fishable hatch of these mayflies every season on one of my favorite PA brook trout headwaters. If that conjures a picture of fishing to 6-7" dinks, you'll need to double those numbers to appreciate how special this stream really is. Add to that an image of the fish rising to these beautiful "mystery mayflies" that hatch in the evening, following a day-long emergence of Dark Green Drakes (Litobrancha recurvata)!

It is such a special event that it is one of the very few things that can pull me away from fishing my favorite Olive Morning Dun hatch (Drunella lata, nee cornuta). Help!

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References

Taxonomy
Species in Heptagenia
Heptagenia adaequata22
Heptagenia culacantha24
Heptagenia diabasia00
Heptagenia elegantulaPale Evening Dun16
Heptagenia pullaGolden Dun324
Heptagenia solitariaGray Fox38
6 species (Heptagenia dolosa, Heptagenia flavascens, Heptagenia julia, Heptagenia marginalis, Heptagenia patoka, and Heptagenia townesi) aren't included.
Genus Range
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