Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin

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.

I caught several wild and colorful 8-9 inch brook trout in the clear little pool below this waterfall.

From Mystery Creek # 89 in New York

Stream photos

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Kogotus Stonefly Nymph Kogotus Stonefly Nymph

Dorsal view of a Kogotus (Perlodidae) Stonefly Nymph from Mystery Creek #199 in Washington

This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.

8 Recently Added Photos

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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Mayfly Genus Heptagenia

This page only contains pictures of specimens.

To read about Heptagenia, visit Page 1.

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Specimens of the Mayfly Genus Heptagenia

1 Male Dun

Male Heptagenia culacantha Mayfly Dun

3 Pictures

Photo credit: Hyun Kounne

Dorsal view of a Male Heptagenia culacantha (Heptageniidae) Mayfly Dun from the Delaware River in New York

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.

Collected June 2, 2017 from the Delaware River in New York

Added by Troutnut on December 5, 2019

Collected June 2, 2017 from the Delaware River in New York and added by Troutnut on December 5, 2019

4 Male Spinners

Male Heptagenia solitaria (Ginger Quill) Mayfly Spinner

4 Pictures

Male Heptagenia solitaria (Heptageniidae) (Ginger Quill) Mayfly Spinner from the Flathead River-lower in Montana

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.

Collected July 3, 2005 from the Flathead River-lower in Montana

Added by Bnewell on June 28, 2011

Collected July 3, 2005 from the Flathead River-lower in Montana and added by Bnewell on June 28, 2011

Male Heptagenia solitaria (Ginger Quill) Mayfly Spinner

3 Pictures

Collected July 4, 2005 from the Flathead River-Lower in Montana

Added by Bnewell on June 27, 2011

Collected July 4, 2005 from the Flathead River-Lower in Montana and added by Bnewell on June 27, 2011

Male Heptagenia adaequata Mayfly Spinner

2 Pictures

Male Heptagenia adaequata (Heptageniidae) Mayfly Spinner from the Columbia River in Washington

Collected July 21, 2012 from the Columbia River in Washington

Added by Bnewell on July 26, 2012

Collected July 21, 2012 from the Columbia River in Washington and added by Bnewell on July 26, 2012

Male Heptagenia culacantha Mayfly Spinner

1 Picture

Male Heptagenia culacantha (Heptageniidae) Mayfly Spinner from the Susquehanna River in Pennsylvania

This photo was provided by guide Eric Naguski along with the following comments, "I took this photo just upstream of Three Mile Island on the east shore of the Susquehanna River just below where the Swatara Creek enters. The Susquehanna is not an easy river to sample for bugs in my opinion. It is very large and pushes a lot of water. Especially in the spring when you would collect mature culacantha nymphs. And I don't believe that there are a ton of these Heptageniids around. Also the people who are doing most of the sampling like myself are doing so for water quality monitoring work so they only take the specimens down to genus-level taxonomy".

Collected October 21, 2011 from the Susquehanna River in Pennsylvania

Added by Entoman on February 9, 2012

Collected October 21, 2011 from the Susquehanna River in Pennsylvania and added by Entoman on February 9, 2012

5 Nymphs

Heptagenia pulla (Golden Dun) Mayfly Nymph

11 Pictures

Dorsal view of a Heptagenia pulla (Heptageniidae) (Golden Dun) Mayfly Nymph from the Yakima River in Washington

This specimen is interesting because Heptagenia pulla has not been reported from Washington or neighboring states (Saskatchewan is the closest), yet the distinctive key characteristics are clear. Furthermore, it might even be a species not listed on this site—Jacobus et al. (2014) writes, "the northern and western specimens of H. pulla may in fact be a synonym of the Palearctic species H. dalecarlica Bengtsson (Kjaerstad et al. 2012) and the true H. pulla may be restricted to eastern North America."

It keys to the genus Heptagenia because the tarsal claw has a single basal tooth, and the gills on segment 7 have fibrils.

For the species key in Jacobus et al. (2014):
1. The left mandible is planate, whereas the right mandible is angulate.
2. The labrum is much wider than long.
3. There's a thin light-colored streak lateral to the eye on the head.

Collected April 8, 2021 from the Yakima River in Washington

Added by Troutnut on April 12, 2021

Collected April 8, 2021 from the Yakima River in Washington and added by Troutnut on April 12, 2021

Heptagenia elegantula (Pale Evening Dun) Mayfly Nymph

6 Pictures

Dorsal view of a Heptagenia elegantula (Heptageniidae) (Pale Evening Dun) Mayfly Nymph from Eighteenmile Creek in Wisconsin

Collected June 4, 2005 from Eighteenmile Creek in Wisconsin

Added by Troutnut on May 24, 2006

Collected June 4, 2005 from Eighteenmile Creek in Wisconsin and added by Troutnut on May 24, 2006

Heptagenia pulla (Golden Dun) Mayfly Nymph

8 Pictures

Dorsal view of a Heptagenia pulla (Heptageniidae) (Golden Dun) Mayfly Nymph from Nome Creek in Alaska

Like most Alaskan mayflies, this one is tricky to identify to the species level. See the discussion section for an informative chat about this one's ID. The current leaning is to call it a fairly immature Heptagenia pulla nymph, but a case has been made for Heptagenia elegantula as well.

Collected July 9, 2011 from Nome Creek in Alaska

Added by Troutnut on July 13, 2011

Collected July 9, 2011 from Nome Creek in Alaska and added by Troutnut on July 13, 2011

Heptagenia pulla (Golden Dun) Mayfly Nymph

5 Pictures

Lateral view of a Heptagenia pulla (Heptageniidae) (Golden Dun) Mayfly Nymph from the Long Lake Branch of the White River in Wisconsin

I used a microscope to positively identify this nymph as Heptagenia pulla. (Edit six years later: I wish I had explained why I was positive about this. It may have been based on color patterns in an angling text, which are not especially reliable for species ID anymore.)

Collected June 4, 2005 from the Long Lake Branch of the White River in Wisconsin

Added by Troutnut on May 25, 2006

Collected June 4, 2005 from the Long Lake Branch of the White River in Wisconsin and added by Troutnut on May 25, 2006

Heptagenia solitaria (Ginger Quill) Mayfly Nymph

1 Picture

Heptagenia solitaria (Heptageniidae) (Ginger Quill) Mayfly Nymph from the Flathead River-lower in Montana

Collected February 26, 2005 from the Flathead River-lower in Montana

Added by Bnewell on June 28, 2011

Collected February 26, 2005 from the Flathead River-lower in Montana and added by Bnewell on June 28, 2011

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!

5 more discussions