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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.

Dorsal view of a Glossosoma (Glossosomatidae) (Little Brown Short-horned Sedge) Caddisfly Larva from the Yakima River in Washington
I caught this tiny larva without a case, but it seems to key pretty clearly to to Glossosomatidae. From there, the lack of sclerites on the mesonotum points to either Glossosoma or Anagapetus. Although it's difficult to see in a 2D image from the microscope, it's pretty clear in the live 3D view that the pronotum is only excised about 1/3 of its length to accommodate the forecoxa, not 2/3, which points to Glossosoma at Couplet 5 of the Key to Genera of Glossosomatidae Larvae.
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 Iswaeon rubrolaterale (Little Olives)

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 Pseudocloeon rubrolaterale
Body length: 4 mm
Wing length: 4 mm

Abdominal tergites 2-6 of male imago pale yellowish white; large lateral maroon patches on each.

Turbinate eyes of moderate size, almost circular; reddish brown in dried specimen. Head and thorax deep blackish; pleural membranes paler brown. Legs pale yellowish white; fore femur with smoky tinges. Wings hyaline, venation pale. Abdominal tergites 2-6 pale yellowish white; very distinct large lateral maroon or wine-colored patches on each; sternites pale, each with a small brown dot near the center, on the mid-ventral line. Tergites 7-10 sepia brown; lateral patches visible in certain lights; sternites paler brown, with mid-ventral dark dots. Tails and forceps pale.

The prominent wine-colored lateral patches on the tergites distinguish this species from all others thus far described.


Start a Discussion of Iswaeon rubrolaterale

References

  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Iswaeon rubrolaterale (Little Olives)

Taxonomy
Species Range
Common Name
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