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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.

Lateral view of a Male Baetidae (Blue-Winged Olive) Mayfly Dun from Mystery Creek #308 in Washington
This dun emerged from a mature nymph on my desk. Unfortunately its wings didn't perfectly dry out.
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 Ironodes geminatus

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.

Female Dun

Body length: ? mm
Wing length: 8-9.5 mm

This species was described from male and female subimagos and a female imago. Description comparative, the species said to resemble Heptagenia sulphurea Mull. European and H. elegantula Etn., in the female sex. Vertex of head of female “‘suffused with light reddish brown, no black spots near the eyes either on the vertex or on the face, nor any at the bases of the coxae.” Wings hyaline; membrane tinted uniformly with very pale yellowish. Venation brownish black, the main longitudinal veins being amber-colored near the base. Tails whitish, not darker at joinings.


Start a Discussion of Ironodes geminatus

References

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