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

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.
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.

Posts: 24
Isidro on Mar 17, 2008March 17th, 2008, 9:34 pm EDT
Im' not hoping an ID, due to the "success" of the last post of European mayflies. I suppose that if t's almost impossible identify mayflies by photo at adult phases, much more difficult will be at nymphal phases. But, maybe someone know, at least, the family of this one. This nymph was caught at Ebro river, in Zaragoza, NE Spain. This river is great and deep, slow and highly contaminated, with lime. The nymph sizes about 15 mm (without cerci). Can be identified, at least, at family level?

Many thanks.
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on Mar 18, 2008March 18th, 2008, 1:12 am EDT

Your mayfly nymph appears to be a clinger of family Heptageniidae, perhaps of genus Ecdyonurus. Given a decent macro photo, identifying mayflies to family and genus is actually somewhat easier with nymphs than with the winged lifestages, as the gross features on the nymphal lifestage are much more distinctive.
Best regards,
Roger Rohrbeck
Posts: 24
Isidro on Mar 26, 2008March 26th, 2008, 2:34 am EDT
Many thanks Taxon! This is very surprising for me. I hoped that teh adults would be much more easily identified than nymphs. The picture is not good but my camera don't give more. Thanks again for de ID.

Quick Reply

Related Discussions

Last Reply
Sep 15, 2006
by Troutnut
Troutnut.com is copyright © 2004-2023 (email Jason). privacy policy