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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.

Dorsal view of a Grammotaulius betteni (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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 May 28, 2007

Updates from May 28, 2007

Photos by Troutnut from Brodhead Creek in Pennsylvania

Early morning sunshine beats through the trees, heating the water up for a Drunella hatch.

From Brodhead Creek in Pennsylvania
A few nice trout were rising in this deep pool during the tail end of a morning Drunella hatch, but I didn't manage to fool them.

From Brodhead Creek in Pennsylvania

Underwater photos by Troutnut from Brodhead Creek in Pennsylvania

Late May finds many trout streams brimming with tiny minnow fry in large schools.

On-stream insect photos by Troutnut from Brodhead Creek in Pennsylvania

A freshly emerged female Drunella cornuta dun.

From Brodhead Creek in Pennsylvania
Brodhead Creek in Pennsylvania
Brodhead Creek in Pennsylvania
Here's the bottom of a freshly emerged male Drunella cornuta dun, showing a lighter shade of olive than the specimens I photographed with my better camera in the evening.

From Brodhead Creek in Pennsylvania
Brodhead Creek in Pennsylvania

Closeup insects by Troutnut from Paradise Creek and Brodhead Creek in Pennsylvania

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