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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 Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
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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Failed attempt at the Ruby

Failed attempt at the Ruby

By Troutnut on July 7th, 2019
I tried for a couple hours to fish the Ruby River at a public fishing access site below the reservoir, but nothing was happening. The water was pretty high and off-color, probably thanks to recent thunderstorms. I don't think I even found a strike, but I did collect a couple good bugs.

Photos by Troutnut from the Ruby River in Montana

The Ruby River in Montana

Closeup insects by Troutnut from the Ruby River in Montana

Lateral view of a Male Rhithrogena hageni (Heptageniidae) (Western Black Quill) Mayfly Spinner from the Ruby River in Montana
Although I could not find the preserved specimen to examine under my good new microscope, I'm tentatively calling it one Rhithrogena hageni, based on apparent similarity to this specimen, which I was able to positively ID.

The relative angle of the penes is a bit shallower in this specimen, but I photographed another specimen from the same collecting trip (and I think even the same swarm, although I don't recall for sure) as the other one, and it had the shallower angle seen on this specimen. I'm guessing it's just variation within the species.
Lateral view of a Male Hydropsychidae Caddisfly Adult from the Ruby River in Montana

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