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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.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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 Genus Cheumatopsyche (Little Sister Sedges)

To generalize broadly, Cheumatopsyche is found lower in the watershed than the similar genera Hydropsyche and Ceratopsyche. It is also smaller, but there is wide variation in size and color between the species. See the family Hydropsychidae page for life cycle details common to these genera.

The most important trout stream species are Cheumatopsyche campyla and Cheumatopsyche pettiti.

Where & when

In 1233 records from GBIF, adults of this genus have mostly been collected during June (28%), July (22%), May (17%), August (15%), April (7%), and September (7%).

In 444 records from GBIF, this genus has been collected at elevations ranging from 10 to 9186 ft, with an average (median) of 2690 ft.

Genus Range

Specimens of the Caddisfly Genus Cheumatopsyche

1 Male Adult
2 Female Adults
1 Adult
3 Pupae

Start a Discussion of Cheumatopsyche


Caddisfly Genus Cheumatopsyche (Little Sister Sedges)

35 species (Cheumatopsyche analis, Cheumatopsyche aphanta, Cheumatopsyche arizonensis, Cheumatopsyche bibbensis, Cheumatopsyche burksi, Cheumatopsyche cahaba, Cheumatopsyche comis, Cheumatopsyche edista, Cheumatopsyche ela, Cheumatopsyche enonis, Cheumatopsyche flinti, Cheumatopsyche gelita, Cheumatopsyche geora, Cheumatopsyche gordonae, Cheumatopsyche gyra, Cheumatopsyche halima, Cheumatopsyche helma, Cheumatopsyche kinlockensis, Cheumatopsyche logani, Cheumatopsyche mickeli, Cheumatopsyche minuscula, Cheumatopsyche mollala, Cheumatopsyche morsei, Cheumatopsyche oxa, Cheumatopsyche parentum, Cheumatopsyche petersi, Cheumatopsyche pinaca, Cheumatopsyche pinula, Cheumatopsyche richardsoni, Cheumatopsyche rossi, Cheumatopsyche smithi, Cheumatopsyche vannotei, Cheumatopsyche virginica, Cheumatopsyche wabasha, and Cheumatopsyche wrighti) aren't included.
Genus Range
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