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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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Male Epeorus vitreus (Heptageniidae) (Sulphur) Mayfly Dun from the Beaverkill River in New York
This is my favorite mayfly from 2004, and it appears on my popular Be the Trout: Eat Mayflies products. Check them out!

Its identification is really up in the air. It might be a late-season vitreus dun but it may very well be one of the more obscure species in that genus.
Troutnut
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Bellevue, WA

Posts: 2758
Troutnut on Jul 2, 2006July 2nd, 2006, 4:49 pm EDT
This is one of my favorite specimens from the old site pictures. I collected it in early September during a fishable hatch of its kind on a smooth, deep pool on the Beaverkill.

The eyes seem nearly contiguous, the first two segments of the fore tarsi are of equal length, and the wings are unmarked, all of which suggest Epeorus. From the above/side picture I can see that the basal costal crossveins do not slant upward as they should with Epeorus, although the main side view seems to maybe show that. I wish I had a better camera when I photographed this one.

It also pretty strongly resembles the E. vitreus dun shown in Ted Fauceglia's book, Mayflies. It clearly does not match the E. vitreus dun pictured on Color Plate XII of Hatches II, but it looks like the unidentifeid eastern Epeorus species on Color Plate XIII of the same book.

By some accounts, there does not seem to be a common eastern species of Epeorus hatching this late, but other books show it on the tail end of the emergence times for Epeorus vitreus. So that's my best guess for now.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on Oct 28, 2008October 28th, 2008, 8:15 am EDT
The little dark marks on the posterior part of the tergites and the dark humeral vein seem consistent with a vitreus ID.

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