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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

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.

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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Lateral view of a Female Rhithrogena (Heptageniidae) Mayfly Spinner from the West Branch of the Delaware River in New York
I'm very tentatively (see the connected forum thread) sticking this mayfly in Rhithrogena for now.
Troutnut's profile picture
Bellevue, WA

Posts: 2758
Troutnut on Jun 8, 2007June 8th, 2007, 11:10 am EDT
I didn't even recognize it as a member of that family at first, but it seems to be the only option. The hind tarsus is distinctly 5-segmented, which I verified under the microscope because you can't see it very well on my photos. However, I because it's a female spinner I can't key it to genus using the Merrit & Cummins keys. Does anyone just recognize it?

I found it drifting, nearly dead on the surface at about 5pm on a hot afternoon.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Konchu's profile picture
Site Editor

Posts: 498
Konchu on Jun 9, 2007June 9th, 2007, 2:07 am EDT
Ignoring all other details, the body shape & color and leg markings resemble some Epeorus and Rhithrogena. Possibly Rhithrogena is the closest. I collected some about like this with male spinners a few weeks ago in Tennessee.
Troutnut's profile picture
Bellevue, WA

Posts: 2758
Troutnut on Jun 9, 2007June 9th, 2007, 4:16 am EDT
I was considering Rhithrogena too because it has a few of those anastomosed crossveins. They just aren't as prominent as I've seen in most illustrations, which gave me cause for doubt. I'll tentatively stick it in there for now.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Madrid España

Posts: 1
Tana on Jan 31, 2009January 31st, 2009, 9:15 pm EST
Hola, Creo que no es posible determinar un insecto de estas caracteristicas en esste estado, ha tantos tipos de Rhithrogena que no podria saber si realmente es alguna, en estados adultos yo en España recomiendo imitar color y tamaño, a mi me parece que se puede sustituir por la March Bronw, recomiendo leer esto:

Un saludo a todos Tana
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on Feb 1, 2009February 1st, 2009, 6:24 am EST
Although the translation may be less than perfect,
this is (more or less) what Tana is saying
when translated to English:

Hello, I think it is not possible to identify an insect of its kind in this state,
has many different types of Rhithrogena could not really tell if any,
adult I recommend imitate Spain in color and size,
I find that you can replaced by the March Brown,
I read this:


Best regards,
Roger Rohrbeck

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Jun 18, 2007
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