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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.
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Drunella grandis (Western Green Drake) Mayfly Nymph Pictures

Dorsal view of a Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Nymph from the Gallatin River in Montana
Ruler view of a Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Nymph from the Gallatin River in Montana The smallest ruler marks are 1 mm.
Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Nymph from the Gallatin River in Montana

This mayfly was collected from the Gallatin River in Montana on July 2nd, 2019 and added to Troutnut.com by Troutnut on July 18th, 2019.


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Drunella grandis (Western Green Drake) Mayfly Nymph Pictures

Collection details
Location: Gallatin River, Montana
Date: July 2nd, 2019
Added to site: July 18th, 2019
Author: Troutnut
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