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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 Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington
As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.
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 Ephemera

This genus of large mayflies boasts three species of great importance. Ephemera simulans and Ephemera guttulata, the Brown Drakes and Green Drakes, are both legendary for short-lived periods of blizzard-like hatches. The Yellow Drakes, Ephemera varia, have a slow and steady emergence period, providing consistent low-key action for several midsummer weeks.

Ephemera blanda is a very localized species and unimportant to most anglers. Ephemera compar, sometimes mentioned in older books as a minor Western hatch, is now considered to be extinct.

Several important characteristics vary between the three important species. Read about each one for details.

Where & when

In 137 records from GBIF, adults of this genus have mostly been collected during June (51%), July (26%), May (15%), and August (5%).

In 32 records from GBIF, this genus has been collected at elevations ranging from 3 to 5912 ft, with an average (median) of 1781 ft.

Genus Range

Nymph biology

Most Ephemera species burrow into rougher substrate than Hexagenia nymphs do. They inhabit sand and fine gravel more frequently than firm silt, although they are found in those environments too.

Specimens of the Mayfly Genus Ephemera

1 Male Dun
2 Female Duns
3 Male Spinners
2 Female Spinners
13 Nymphs

3 Streamside Pictures of Ephemera Mayflies:

2 Underwater Pictures of Ephemera Mayflies:

Discussions of Ephemera

Green Drake Hatch Temp?
1 replies
Posted by NEMatt on May 23, 2014 in the species Ephemera guttulata
Last reply on May 23, 2014 by Entoman

I was looking for a water temperature range for the Green Drake hatch. Anyone know?
GD Shuck
10 replies
Posted by Martinlf on May 29, 2013 in the species Ephemera guttulata
Last reply on Jun 2, 2013 by Crepuscular
Jason's photo of a GD shuck suggests that at hatch time the backs of the nymphs may be a greyish or grey olive color. Possibly useful information, if this is an accurate surmise.
Brown Drake?
20 replies
Posted by Derdmann on Jun 19, 2011 in the species Ephemera simulans
Last reply on Jun 29, 2011 by TNEAL
Came across a mayfly on the Paint River by Crystal Falls, Michigan on June 17th. Is it a brown drake?
Emergence period of green drakes
5 replies
Posted by Beardius on Aug 1, 2008 in the species Ephemera guttulata
Last reply on Dec 4, 2008 by Beardius
Emergence periods for green drakes usually run for 7-10 days in most streams. However, there are streams in the east where emergence periods are prolonged by some of the nymphs being parasitized by Nanocladius and Epoicocladius midge larvae. In these streams, emergence may be prolonged to 21 days. Unparasitized nymphs emerge before parasitized nymphs, with each group showing separate peaks of emergence about a week apart. This is based upon my own research on green drake emergence in streams with these midge species.

My question here is this: does anybody know of streams that have this type of prolonged emergence (2-3 weeks) in NY, PA, MD, or WV?
Green Drake Hatch Frustrations
7 replies
Posted by Billy on Jun 6, 2007 in the species Ephemera guttulata
Last reply on Jun 12, 2007 by GONZO
We were fortunate this past weekend to be on Pine Creek during the Green Drake hatch. The spinner fall was incredible. A question I have is why do we miss so many strikes and yet, using the same techniques, the ones we do catch and release practically hook themselves. We were getting strikes on Green Drake Duns and Cripples and Spinners.

One individual described it to us that after observing the trout underwater during a Green Drake hatch, many of the strikes pull a small part of the fly (wing, leg) underwater and they swirl and swallow it there. If that is true, then I can rationalize missing more than 18 fish this weekend. If anyone has observed this please post your observations. Normally we do not have such a great contrast in miss to hookup ratio.

Start a Discussion of Ephemera


Mayfly Genus Ephemera

Genus Range
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