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.

Firehole River Sunset

From the Firehole River in Wyoming

Stream photos

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Re: Trico emergers
In the Mayfly Genus Tricorythodes by Bwoklink (Martinlf replied)

Re: Trico Tips
In the Mayfly Genus Tricorythodes by Martinlf

Re: UV spectrum and trout
In General Discussion by Martinlf

Re: closing the gender gap in flyfishing
In General Discussion by Konchu (Smallflyguy replied)

Re: Fishing Kupa River, Slovenia
In Fishing Reports by Slocum (Fish1 replied)

Male Ameletus vernalis (Brown Dun) Mayfly Nymph Male Ameletus vernalis (Brown Dun) Mayfly Nymph

Dorsal view of a Male Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Icicle River in Washington

Keying this one out using Zloty & Pritchard 1997:
-No ganglionic markings on sternites 2–8
-Posterior margins of sternits 6–8 without numerous spines
-Mesal gill extension well developed (I really don't like the "well developed" language when it's subjective, but in this case the other option doesn't lead anywhere productive)
-Tails pale in basal 1/3
-Larger species (13–16 mm) — this one is just shy of 12 mm, but closer to 13 than to <10
-Spring emergence
This all points to Ameletus vernalis.

7 Recently Added Photos

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.

Updates from July 30, 2010

Closeup insects by Bnewell from the Flathead River and Flathead Lake in Montana

Male Drunella flavilinea (Flav) Mayfly Spinner

1 Picture

Male Drunella flavilinea (Ephemerellidae) (Flav) Mayfly Spinner from the Flathead River-lower in Montana

Collected July 30, 2010 from the Flathead River-lower in Montana

Added by Bnewell on June 29, 2011

Collected July 30, 2010 from the Flathead River-lower in Montana and added by Bnewell on June 29, 2011

Male Hexagenia limbata (Hex) Mayfly Dun

2 Pictures

Male Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from Flathead Lake in Montana

This species is very abundant in Flathead and Whitefish Lakes with a smaller population in lakes of the Swan River Drainage, and a few in Lake McDonald in Glacier Park. This species usually emerges along with Ephemera simulans.

Collected July 30, 2010 from Flathead Lake in Montana

Added by Bnewell on June 29, 2011

Collected July 30, 2010 from Flathead Lake in Montana and added by Bnewell on June 29, 2011