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.

The trees were leafing out and the trout were rising on this productive Wisconsin stream

From the Namekagon River in Wisconsin

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.

Caddisfly Genus Neureclipsis (Little Red Twilight Sedges)

This genus is reported to be important on trout streams sometimes, but not often. The only species individually mentioned is not considered to be important.

Where & when

In 276 records from GBIF, adults of this genus have mostly been collected during June (24%), July (22%), May (19%), August (18%), and September (12%).

In 99 records from GBIF, this genus has been collected at elevations ranging from 3 to 4544 ft, with an average (median) of 1178 ft.

Genus Range

source

Map of specific collection sites

Larva & pupa biology

Current speed: Slow

Shelter type: Nets

Gary LaFontaine describes the unique net arrangement of these larvae in Caddisflies:

The carnivorous larvae string their trumpet-shaped nets on debris and rooted plants poking up from the bottom. They arrange them vertically on the object, each net filtering its victims from one little slice of the water column.

Start a Discussion of Neureclipsis

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.
LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
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.