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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.

Ventral view of a Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Larva from the Yakima River in Washington
With a bit of help from the microscope, this specimen keys clearly and unsurprisingly to Hydropsyche.
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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Mayfly Species Epeorus suffusus

Where & when

Time of year : June

Species Range

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Male Spinner

Described in Needham et al (1935) as Iron suffusus
Body length: 11 mm
Wing length: 11? mm

Similar to dark form of I. humeralis (now a synonym for Epeorus vitreus) but with larger genitalia, and the penes more widely separated apically.

Larger than dark form of I. humeralis, and with larger eyes. Thorax dull brown, the posterior portions deeper brown. Legs pale yellowish; all femora with median and apical dark spots. Venation pale. Abdominal tergites suffused with brown, except for a double row of oval white spots. Tails pale; traces of brown rings at the basal joinings. Penes quite similar in shape to those of I. humeralis, but larger and more widely separated apically. The larger size and slight structural differences in the penes seem to distinguish this species from I. humeralis, dark form.


Start a Discussion of Epeorus suffusus

References

  • Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.
  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Epeorus suffusus

Species Range
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