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.

I caught a nice brookie a few weeks earlier in this pool at the junction of a split channel in the stream. The huge fallen tree is great cover.

From the Mystery Creek # 23 in New York

Stream photos

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Neoleptophlebia Mayfly Nymph Neoleptophlebia Mayfly Nymph

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington

Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.

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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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Stonefly Species Haploperla chilnualna (Sallflies)

Species Range

source

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 Adult

Described in Ricker (1952)

Body length: 5 mm

Length from head to tip of wings 6.5 mm. Color yellow, without dark markings. Very similar to the widespread Haploperla brevis, but the anal venation of the hindwing is not quite so reduced : vein A₁ usually terminates slightly distad of the position of the proximal intercubital crossvein, instead of proximad as in Haploperla brevis. However, the anal area apparently does not fold, and vein A₁ is much shorter than in Rasvena or (still more) Chloroperla sensu stricto. Vein A₂ of the hindwing present but short. Vein A₂ of the forewing undivided.

The supra-anal process is erect and has a short hook directed forward (Fig. 151). The hooked supra-anal process best distinguishes this species from Haploperla brevis.

Start a Discussion of Haploperla chilnualna

References

Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
Ricker, W.E. 1952. Systematic Studies in Plecoptera. Indiana University Publications Science Series 18: 1-200.