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.

9 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.

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Caddisfly Species Limnephilus externus (Summer Flier Sedges)

Where & when

In 101 records from GBIF, adults of this species have mostly been collected during August (30%), September (28%), July (20%), October (13%), and June (8%).

In 70 records from GBIF, this species has been collected at elevations ranging from 3 to 22123 ft, with an average (median) of 1932 ft.

Species Range

source

Map of specific collection sites

Specimens of the Caddisfly Species Limnephilus externus

1 Adult

Limnephilus externus (Summer Flier Sedge) Caddisfly Adult

1 Picture

Limnephilus externus (Limnephilidae) (Summer Flier Sedge) Caddisfly Adult from the Touchet River in Washington

Collected September 14, 2011 from the Touchet River in Washington

Added by Bnewell on September 21, 2011

Collected September 14, 2011 from the Touchet River in Washington and added by Bnewell on September 21, 2011

1 Male Adult

Male Limnephilus externus (Summer Flier Sedge) Caddisfly Adult

5 Pictures

Lateral view of a Male Limnephilus externus (Limnephilidae) (Summer Flier Sedge) Caddisfly Adult from the Henry's Fork of the Snake River in Idaho

Collected August 10, 2018 from the Henry's Fork of the Snake River in Idaho

Added by Troutnut on June 12, 2019

Collected August 10, 2018 from the Henry's Fork of the Snake River in Idaho and added by Troutnut on June 12, 2019

1 Larva

Limnephilus externus (Summer Flier Sedge) Caddisfly Larva

1 Picture

Limnephilus externus (Limnephilidae) (Summer Flier Sedge) Caddisfly Larva from Temporary ponds- Glacier Nat. Park in Alaska

This caddis is one of the most abundant caddisflies in temporary ponds of Glacier Park. The larvae build a round case of detritus and dead plant material that can get quite large.

Collected June 24, 2008 from Temporary ponds- Glacier Nat. Park in Alaska

Added by Bnewell on June 26, 2011

Collected June 24, 2008 from Temporary ponds- Glacier Nat. Park in Alaska and added by Bnewell on June 26, 2011