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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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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Taxon
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Site Editor
Plano, TX

Posts: 1311
Taxon on Apr 18, 2007April 18th, 2007, 8:17 pm EDT
Okay, does anyone recognize this mayfly. I am guessing that it's a female subimago of genus Isonychia, but it sure has striking coloration.

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
Troutnut
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Administrator
Bellevue, WA

Posts: 2758
Troutnut on Apr 19, 2007April 19th, 2007, 4:13 am EDT
I think you're right. I couldn't say what species it is, but I don't see any reason not to presume I. bicolor.

I'm also not 100% positive it's a female, since the rear end is pretty blurry. Males in Isonychia have unusually small eyes.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Quillgordon
Schuylkill County, PA.

Posts: 109
Quillgordon on Apr 19, 2007April 19th, 2007, 6:46 am EDT
Taxon,
Aren't the legs a big key here.
Front legs ..... brown
Mid/rear legs ....... cream (white)

* Charles Wetzel called the female spinner the 'White-gloved Howdy'.

Q.g.
Flyfishing is a state of mind! .............. Q.g.

C/R........barbless
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on Apr 19, 2007April 19th, 2007, 7:20 am EDT
Roger-
This certainly looks like Isonychia to me. There are several Iso species with a southern distribution, so I won't hazard a guess about species.

John-
The leg colors you mention are pretty typical of Isonychia. Wetzel's "white-gloved howdy" name referred to the white-tipped front legs of the bicolor female, held out as if awaiting a greeting handshake. (I love that name!)
Quillgordon
Schuylkill County, PA.

Posts: 109
Quillgordon on Apr 19, 2007April 19th, 2007, 7:55 am EDT
John-
The leg colors you mention are pretty typical of Isonychia. Wetzel's "white-gloved howdy" name referred to the white-tipped front legs of the bicolor female, held out as if awaiting a greeting handshake. (I love that name!)


* female spinner only....... @ 'Matching the Hatch', E. Schwiebert Jr. (pg.71).

Right....... These guys from PA. were pretty smart, weren't they. ..... LOL........
Flyfishing is a state of mind! .............. Q.g.

C/R........barbless
Taxon
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Site Editor
Plano, TX

Posts: 1311
Taxon on Apr 19, 2007April 19th, 2007, 10:54 am EDT
Gonzo-

Roger-
This certainly looks like Isonychia to me. There are several Iso species with a southern distribution, so I won't hazard a guess about species.


Right. There are actually (6) Isonychia species known to be in Alabama, and of those, only I. bicolor is described in flyfishing entomology literature.


Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
Taxon
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Site Editor
Plano, TX

Posts: 1311
Taxon on Apr 19, 2007April 19th, 2007, 11:11 am EDT
Jason-

I'm also not 100% positive it's a female, since the rear end is pretty blurry. Males in Isonychia have unusually small eyes.


Right. Aren't blurry rear ends just the pits! However, I believe the brownish blur is actually some basal cerci segments rather than claspers. Neither the fore legs nor eyes offered much help either. Actually, the character that caused me lean toward female, was the wing venation, which I believe to be more heavily stained in female than male Isonychia.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

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