Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York

Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Looking across Island Lake toward the Titcomb Basin—one of the popular crown jewels of the Wind River Mountains

From Island Lake in Wyoming

Stream photos

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Ephemerella mucronata Mayfly Nymph Ephemerella mucronata Mayfly Nymph

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.

17 Recently Added Photos

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.

Female Paraleptophlebia (Blue Quills and Mahogany Duns) Mayfly Dun Pictures

I really hoped to catch some good blue quill specimens on this trip, but they are very fragile mayflies and this one was in the best condition of the few that I caught after I drove them home to my camera. It may not be pretty, but you get an idea of the size/shape/color anyway.

Lateral view of a Female Paraleptophlebia (Leptophlebiidae) (Blue Quill) Mayfly Dun from the Beaverkill River in New York

Ventral view of a Female Paraleptophlebia (Leptophlebiidae) (Blue Quill) Mayfly Dun from the Beaverkill River in New York

Dorsal view of a Female Paraleptophlebia (Leptophlebiidae) (Blue Quill) Mayfly Dun from the Beaverkill River in New York

Ruler view of a Female Paraleptophlebia (Leptophlebiidae) (Blue Quill) Mayfly Dun from the Beaverkill River in New York The smallest ruler marks are 1 mm.

This mayfly was collected from the Beaverkill River in New York on April 19th, 2006 and added to Troutnut.com by Troutnut on April 21st, 2006.

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References

Allen RK. 1977. New species of Ephemerella (Ephemerella) from Alberta (Ephemeroptera: Ephemerellidae). The Pan-Pacific Entomologist 53: 286-286.
Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
Merritt R.W., Cummins, K.W., and Berg, M.B. 2019. An Introduction to the Aquatic Insects of North America (Fifth Edition). Kendall/Hunt Publishing Company.