Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin

Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

View from Upper to Lower Titcomb Lake

From Titcomb Basin in Wyoming

Stream photos

Featured on the forum

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)

Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

9 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.

I. hansoni

Isogenoides hansoni (Appalachian Springfly) Stonefly Nymph

11 Pictures

Dorsal view of a Isogenoides hansoni (Perlodidae) (Appalachian Springfly) Stonefly Nymph from Mongaup Creek in New York

This large Perlodidae stonefly was a strikingly bright yellow color, more so than any other insect I've seen. I didn't enhance it much. See the discussion threads to follow how we identified this specimen, which was listed incorrectly for several years.

Collected April 18, 2006 from Mongaup Creek in New York

Added by Troutnut on April 21, 2006

Collected April 18, 2006 from Mongaup Creek in New York and added by Troutnut on April 21, 2006

GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681

GONZO on Oct 3, 2010October 3rd, 2010, 8:37 am EDT

I believe that this is actually Isogenoides hansoni. When Dr. Chandler and Luke Myers made earlier "Cultus" comments on this specimen, they seem to have missed the prominent submental gills shown in photo #5 (and #7).

In addition to the submental gills (more than 2X as long as wide), the pale area on the 10th tergum, the distinct enclosed pale "M" mark on the head, and (often) the elongated pale spot in the center of the head are a few of the distinctive traits of this species. A complete description and a depiction of the dorsal habitus (figure #88) can be found in Sandberg and Stewart (Holomorphology and Systematics of the Stonefly Genus Isogeniodes, 2005).

The type specimens of I. hansoni were collected from my old homewaters on the Brodheads in 1937 by Preston Jennings (the author of the classic A Book of Trout Flies).

Cultus verticalis is a smaller, pale yellowish nymph, typically with a bolder, simpler dorsal pattern and less intricate markings on the dorsal surface of the head/thorax.