Header image
Enter a name
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.
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.

Ephemerella tibialis (Little Western Dark Hendrickson) Mayfly Nymph Pictures

Lateral view of a Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Dorsal view of a Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ventral view of a Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
Ruler view of a Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho The smallest ruler marks are 1 mm.
Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho

This mayfly was collected from the East Fork Big Lost River in Idaho on August 3rd, 2020 and added to Troutnut.com by Troutnut on August 19th, 2020.


Start a Discussion of Nymph

References

Ephemerella tibialis (Little Western Dark Hendrickson) Mayfly Nymph Pictures

Collection details
Location: East Fork Big Lost River, Idaho
Date: August 3rd, 2020
Added to site: August 19th, 2020
Author: Troutnut
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy