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.

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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Zapada cinctipes (Tiny Winter Black) Stonefly Nymph Zapada cinctipes (Tiny Winter Black) Stonefly Nymph

Dorsal view of a Zapada cinctipes (Nemouridae) (Tiny Winter Black) Stonefly Nymph from the Yakima River in Washington

Nymphs of this species were fairly common in late-winter kick net samples from the upper Yakima River. Although I could not find a key to species of Zapada nymphs, a revision of the Nemouridae family by Baumann (1975) includes the following helpful sentence: "2 cervical gills on each side of midline, 1 arising inside and 1 outside of lateral cervical sclerites, usually single and elongate, sometimes constricted but with 3 or 4 branches arising beyond gill base in Zapada cinctipes." This specimen clearly has the branches and is within the range of that species.

13 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 Species Helicopsyche borealis (Speckled Peters)

This is the only important trout stream species of Helicopsyche. It has an unusual wing characteristic, described by Gary LaFontaine in Caddisflies:

The adult appears different in flight from other caddisflies because the top set of wings is attached to the bottom by a row of hooks, so the four wings beat together, not as two spread-out sets.

Where & when

Time of year : Early May through July

Preferred waters: Rivers or lakes; best in spring creeks and large rivers

The emergence of this species lasts a few weeks in any given location. It begins in the East in early May and lasts through June, while in the West it begins in mid-June and lasts through early July.

In 137 records from GBIF, adults of this species have mostly been collected during June (23%), July (21%), August (19%), May (12%), September (9%), and April (8%).

In 92 records from GBIF, this species has been collected at elevations ranging from 195 to 10194 ft, with an average (median) of 3509 ft.

Species Range

source

Map of specific collection sites

Hatching behavior

Time of day : Evening

Egg-Laying behavior

Time of day: Evening

LaFontaine gives a slightly confusing account of the ovipositing behaivor of this species in Caddisflies, suggesting that they may flutter around on or near the water's surface looking for solid objects to attach their eggs to, or may drop them in the water. Swisher and Richards give a clearer picture in Selective Trout:

During egg laying, the females float in the surface close to the banks, crawl underwater, and flop on the surface to oviposit. They then ride the water serenely in the normal resting position, and trout take them with gentle rises.

Larva & pupa biology

Diet: Algae, detritus, animal matter

Environmental tolerance: Very tolerant: can thrive in both cold water and hot springs up to 110°F

Shelter type: Coiled sand case shaped like a snail shell

Specimens of the Caddisfly Species Helicopsyche borealis

1 Female Adult

Female Helicopsyche borealis (Speckled Peter) Caddisfly Adult

7 Pictures

Lateral view of a Female Helicopsyche borealis (Helicopsychidae) (Speckled Peter) Caddisfly Adult from the Henry's Fork of the Snake River in Idaho

This one keys pretty easily to the Helicopsychidae family, of which there is only one genus in North America, and one species reported in this general area.

Collected July 30, 2020 from the Henry's Fork of the Snake River in Idaho

Added by Troutnut on August 17, 2020

Collected July 30, 2020 from the Henry's Fork of the Snake River in Idaho and added by Troutnut on August 17, 2020

1 Pupa

Helicopsyche borealis (Speckled Peter) Caddisfly Pupa

13 Pictures

Dorsal view of a Helicopsyche borealis (Helicopsychidae) (Speckled Peter) Caddisfly Pupa from the Yakima River in Washington

I'm calling this one very tentatively Helicopsyche borealis, with some big caveats that I might be wrong.

It seems to key fairly easily to Helicopsychidae, except at the last couplet in Merritt & Cummins (5th ed) it's supposed to have “anal processes short and straight, each with several mesal setae and 2 long apical setae,” whereas this one has VERY short, straight processes with 3 long apical setae and no mesal ones.

Additionally, the only species of Helicopsychidae documented in this region is Helicopsyche borealis, which is supposed to emerge much later in the summer.

Collected April 8, 2021 from the Yakima River in Washington

Added by Troutnut on April 12, 2021

Collected April 8, 2021 from the Yakima River in Washington and added by Troutnut on April 12, 2021

Start a Discussion of Helicopsyche borealis

References

Baumann, Richard W. 1975. Revision of the Stonefly Family Nemouridae (plecoptera) : a Study Of The World Fauna At The Generic Level. Smithsonian Contributions to Zoology undef(211): 1-74.
LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.