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.

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Zapada cinctipes (Tiny Winter Black) Stonefly Nymph Zapada cinctipes (Tiny Winter Black) Stonefly Nymph

Dorsal view of a Zapada cinctipes (Nemouridae) (Tiny Winter Black) Stonefly Nymph from the Yakima River in Washington

Nymphs of this species were fairly common in late-winter kick net samples from the upper Yakima River. Although I could not find a key to species of Zapada nymphs, a revision of the Nemouridae family by Baumann (1975) includes the following helpful sentence: "2 cervical gills on each side of midline, 1 arising inside and 1 outside of lateral cervical sclerites, usually single and elongate, sometimes constricted but with 3 or 4 branches arising beyond gill base in Zapada cinctipes." This specimen clearly has the branches and is within the range of that species.

13 Recently Added Photos

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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Ameletus velox (Brown Dun) Mayfly Nymph Pictures

This Ameletus has puzzled me since I found their exuviae four years ago. Using the key in Larvae and adults of Ameletus mayflies (Ephemeroptera: Ameletidae) from Alberta this appears to key to Ameletus velox. It also sort of matches the color pattern on abdominal segments 6-7 from their figure 20C, which their text mentions as another identifying characteristic. However, one characteristic ("incisor area of left mandible with second denticle much smaller than first") doesn't seem to match. Also, velox is reportedly among the largest Ameletus species, but not quite as large as this nymph. My best guess is still that it represents a bit of undocumented variation on velox.

Lateral view of a Ameletus velox (Ameletidae) (Brown Dun) Mayfly Nymph from Mystery Creek #199 in Washington

Dorsal view of a Ameletus velox (Ameletidae) (Brown Dun) Mayfly Nymph from Mystery Creek #199 in Washington

Ventral view of a Ameletus velox (Ameletidae) (Brown Dun) Mayfly Nymph from Mystery Creek #199 in Washington

Ameletus velox (Ameletidae) (Brown Dun) Mayfly Nymph from Mystery Creek #199 in Washington

Ruler view of a Ameletus velox (Ameletidae) (Brown Dun) Mayfly Nymph from Mystery Creek #199 in Washington The smallest ruler marks are 1 mm.

This mayfly was collected from Mystery Creek #199 in Washington on June 19th, 2023 and added to Troutnut.com by Troutnut on June 21st, 2023.

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References

Baumann, Richard W. 1975. Revision of the Stonefly Family Nemouridae (plecoptera) : a Study Of The World Fauna At The Generic Level. Smithsonian Contributions to Zoology undef(211): 1-74.
Zloty, J and Pritchard, G. 1997. Larvae and adults of Ameletus mayflies (Ephemeroptera: Ameletidae) from Alberta. Canadian Entomologist 129: 251-289.