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.

Stream photos

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Male Baetidae (Blue-Winged Olive) Mayfly Dun Male Baetidae (Blue-Winged Olive) Mayfly Dun

Lateral view of a Male Baetidae (Blue-Winged Olive) Mayfly Dun from Mystery Creek #308 in Washington

This dun emerged from a mature nymph on my desk. Unfortunately its wings didn't perfectly dry out.

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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.

Stillwater Mayfly Nymph Collection Techniques

This topic is about the Insect Order Ephemeroptera

Mayflies may be the most important insects for trout anglers to understand. They are an ancient order of insects, famous outside the fly-fishing world for their fragile beauty and short adult lifespan, often a single day to mate and die. The mayfly's poignant drama attracts poets and anglers alike, but anglers make the most of it.

Mayflies live more than 99% of their lives as nymphs on the river or lake bottom, filling many crucial roles in freshwater ecosystems as they feed and grow. They eventually emerge from the water as winged sub-adults called "subimagos" by scientists and "duns" by anglers. Duns evolved to be good at escaping the water, with a hydrophobic surface and hardy build, but they are clumsy fliers. Within a day or two they molt one last time into "imagos" or "spinners," the mature adults, a transformation captured in this photo series of a dun molting into a spinner. They have longer legs and tails, and sleeker, more lightweight bodies, giving them the airborne speed, agility, and long grasp they need for their midair mating rituals. They are usually darker than the duns and have shinier, more transparent wings. They die within minutes or hours after mating.

Example specimens

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Male Epeorus albertae (Pink Lady) Mayfly Spinner

Lateral view of a Male Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Spinner from the North Fork Stillaguamish River in Washington

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Male Epeorus deceptivus Mayfly Dun

Artistic view of a Male Epeorus deceptivus (Heptageniidae) Mayfly Dun from the South Fork Sauk River in Washington

The lack of a darkened humeral crossvein rules out Epeorus albertae and Epeorus dulciana. The lack of a dark macula on the forefemora rules out Epeorus longimanus. The small size rules out Epeorus grandis and Epeorus permagnus. That leaves as the only possibility known in Washington state Epeorus deceptivus. It is a small species, although not reportedly quite as small as this specimen. I couldn't find anything in the species description in Traver (1935) to definitively confirm or rule out the species ID, given that I don't have the preserved specimen to check under a microscope, but it has to be either deceptivus or something not yet reported in Washington. It was collected at the same time as a similar-sized female dun.

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Female Acentrella turbida (Tiny Blue-Winged Olive) Mayfly Spinner

Lateral view of a Female Acentrella turbida (Baetidae) (Tiny Blue-Winged Olive) Mayfly Spinner from the Middle Fork Snoqualmie River in Washington

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Aug 4, 2011August 4th, 2011, 2:38 pm EDT

Hi Bob-

If you could share your stillwater collection technique(s) for Siphlonorus nymphs, I would be most appreciative.

Sincerely,

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Bnewell

Site Editor
Kennewick, Washington

Posts: 115

Bnewell on Aug 7, 2011August 7th, 2011, 5:06 pm EDT

Roger,

I have an aquatic net on a 5' handle. It is easy to use and easy to store. For the Siphlonorus I sampled a small lake. I merely ran the net through the vegetation and checked the net contents occasionally until I saw something of interest. Siphlonorus can also be found in flowing water. I recently sampled a small stream using this same net. I hold the net perpendicular to current and disturb rocks upstream from the net.

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Aug 7, 2011August 7th, 2011, 5:59 pm EDT

Hi Bob-

Thanks for responding with info concerning the techniques you employ. I have a clear mental picture of the 5' handle, but not the rest the net. Could you possibly post a photo of the net?

Thanks,

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Aug 7, 2011August 7th, 2011, 6:00 pm EDT

I've found many Siphlonurus nymphs in still water near trout streams, from quiet backwaters on the side of the main stream channel to apparently disconnected, seasonal ponds or puddles. They're fast swimmers, but still pretty easy to catch with any kind of net.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Bnewell

Site Editor
Kennewick, Washington

Posts: 115

Bnewell on Aug 8, 2011August 8th, 2011, 9:10 am EDT

Roger,

Your URL is interesting are you heavily involved with entomology?
My email is: bobn708@q.com.

Some more comments about Siphlonurus. I am familiar with 3 species of Siphlonurus. S. phyllis has been collected only in temporary ponds. S. autumnalis and S. occidentalis are known from ponds or very gently flowing water. Siphlonurus eggs can survive drying and freezing thus their survival in temporary ponds. They definitely do not prefer fast flowing water. In standing water, like a small pond formed as a stream drops, you can see them swimming. They are very fast swimmers and at first you might think they are minnows. Sometime they swim so fast they can out-swim your net so you have to be quick with the net.

Hope this helps.

Bob

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Aug 8, 2011August 8th, 2011, 11:27 am EDT

Hi Bob-

Your URL is interesting are you heavily involved with entomology?

I guess you could say that. My website attempts to purvey aquatic entomology and taxonomy info to the flyfishing community. Having been retired for 11 years, it's a real passion, and pretty much how I spend most of my waking hours.

In any event, thanks for the additional info on Siphlonurus nymphal behavior.

Best regards,

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Gutcutter

Pennsylvania

Posts: 470

Gutcutter on Aug 8, 2011August 8th, 2011, 6:03 pm EDT

S. phyllis

Does anybody else think that they could have named this thing of beauty something different?

All men who fish may in turn be divided into two parts: those who fish for trout and those who don't. Trout fishermen are a race apart: they are a dedicated crew- indolent, improvident, and quietly mad.

-Robert Traver, Trout Madness

Entoman

Northern CA & ID

Posts: 2604

Entoman on Aug 8, 2011August 8th, 2011, 6:18 pm EDT

You're a sick man Tony:)

Kurt

"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Aug 9, 2011August 9th, 2011, 12:13 am EDT

I've gotta admit that was a brilliant stroke of perversion.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Goose
Posts: 77

Goose on Aug 11, 2011August 11th, 2011, 7:13 am EDT