Header image
Enter a name
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.

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.
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.

PaulRoberts
PaulRoberts's profile picture
Colorado

Posts: 1776
PaulRoberts on May 4, 2012May 4th, 2012, 7:54 am EDT
Any guesses as to who this is? It's a pretty good sized "golden stone" although it's not very golden -a pale translucent underside and mostly the dorsum mostly in browns. I'd tie it in a size 10 3xl.

Entoman
Entoman's profile picture
Northern CA & ID

Posts: 2604
Entoman on May 4, 2012May 4th, 2012, 7:25 pm EDT
I don't recognize the head capsule pattern off the top of my head, but it sure looks like a perlodid to me Paul, either a Springfly or Stripetail. A few answered questions might help us nail down the genus. Did it have thoracic gills? How about longitudinal abdominal striping (can be very feint). If we can get the choices down to a couple of genera, I'll look though what I've got to see if I can come up with a head match. Your specimen looks pretty distinctive.
"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
PaulRoberts
PaulRoberts's profile picture
Colorado

Posts: 1776
PaulRoberts on May 5, 2012May 5th, 2012, 4:30 pm EDT
No striping. There were some striped (Isoperlid?) guys there. I didn't think to look at gills. If there were, they were small and not visible from the topside (only images I have). Didn't expect to post this originally.
Entoman
Entoman's profile picture
Northern CA & ID

Posts: 2604
Entoman on May 5, 2012May 5th, 2012, 11:28 pm EDT
Well, your answers don't make it as easy as hoped.:) If it had gills they would be small and finger-like or even bumps emanating from the thoracic joints behind the legs and perhaps even from the cervical joint. FWIW I'm not seeing any evidence of them in the photo, though it must be conceded that reliable determinations are much easier if the critter is held upside down for a good close-up of the thorax and head. What to look for are the presence of gills and a good look at the mouth parts and mesosternum.

Assuming a lack of gills, of the five genera lacking this character known for CO, four are represented by single species. Of these four, Cultus is too small and Diura, Arcynopteryx and Skwala look different both in pattern and conformation (wing pad shape, legs, etc.).

While the remaining genus usually has stripes, their absence is not as diagnostic as once thought and the thick narrow cervix, shape of the wingpads, and antennae length sure look right. I'm thinking Isoperla and will start looking there for a head capsule match. Hopefully one exists, though there are at least 11 species reported from CO and to my knowledge many have never been photographed.
"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
PaulRoberts
PaulRoberts's profile picture
Colorado

Posts: 1776
PaulRoberts on May 6, 2012May 6th, 2012, 7:46 am EDT
I'll photo both sides next time.

Quick Reply

Related Discussions

Topic
Replies
Last Reply
4
May 2, 2009
by Wbranch
20
Jan 13, 2015
by Taxon
2
Jan 8, 2009
by Sandfly
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy