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.

Stream photos

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

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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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Caddisfly Species Nyctiophylax affinis (Dinky Light Summer Sedges)

Where & when

Time of year : Early summer

Altitude: Lakes and streams

This widespread species is most common in the Midwest.

In 81 records from GBIF, adults of this species have mostly been collected during June (33%), July (26%), August (19%), May (14%), and September (7%).

In 39 records from GBIF, this species has been collected at elevations ranging from 328 to 7201 ft, with an average (median) of 2887 ft.

Species Range

source

Map of specific collection sites

Specimens of the Caddisfly Species Nyctiophylax affinis

1 Adult

Nyctiophylax affinis (Dinky Light Summer Sedge) Caddisfly Adult

12 Pictures

Nyctiophylax affinis (Polycentropodidae) (Dinky Light Summer Sedge) Caddisfly Adult from the Teal River in Wisconsin

This specimen is certainly Nyctiophylax and most likely Nyctiophylax affinis. I don't know my caddisfly parts well enough to definitively follow the Nyctiophylax key in Morse (1972), but that source states that affinis is the predominant Midwestern species, being widespread and common in the region where I found this one. The anatomy of this one seems to match those at least as well as the other two potential options based on range, Nyctiophylax uncus and Nyctiophylax banksi.

Collected June 7, 2021 from the Teal River in Wisconsin

Added by Troutnut on June 9, 2021

Collected June 7, 2021 from the Teal River in Wisconsin and added by Troutnut on June 9, 2021

Start a Discussion of Nyctiophylax affinis

References

LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
Morse, JC. 1972. The genus Nyctiophylax in North America. Journal of the Kansas Entomological Society 42(2): 172-181.