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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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Lyrae has attached this picture to aid in identification. The message is below.
Lyrae
French Creek, PA

Posts: 1
Lyrae on May 13, 2007May 13th, 2007, 3:12 pm EDT
I saw this on my deck this evening. Anyone have any ideas? I only know enough to catch a few fish :)



Thanks.
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on May 13, 2007May 13th, 2007, 3:48 pm EDT
Lyrae,

Cool mayfly! I can't make out some of the details, but from the overall appearance it looks like a female Siphlonurus spinner to me.
Taxon
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on May 13, 2007May 13th, 2007, 4:03 pm EDT
That was my impression as well, also a female spinner. I'm thinking Siphlonurus alternatus. Don't see any Siphlonurus species listed for PA in my most trusted (national) source. However it's most likely incomplete in that regard.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on May 13, 2007May 13th, 2007, 4:19 pm EDT
Roger,

I can confirm that we do have Siphlonurus in PA. I've seen and even fished them on a few streams. Greg Hoover's 2002 survey of PA mayflies lists barbaroides, mirus, quebecensis, rapidus, and typicus as PA species.
Taxon
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on May 13, 2007May 13th, 2007, 4:35 pm EDT
Gonzo-

Well, we seem to be in violent agreement on genus. And after all, identification to species based on a photograph of a female imago is problematic, at best. However, as Konchu has observed, it is fun.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on May 13, 2007May 13th, 2007, 4:54 pm EDT
Agreed, Roger, it is fun to guess. I was tempted to guess quebecensis, but the only species I can reasonably rule out is mirus.

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