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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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.
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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Acroneuria abnormis (Golden Stone) Stonefly Nymph Pictures

Perlidae stonefly nymph. A large predator of clean freshwater streams

Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York
Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York
Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York
Dorsal view of a Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York
Ventral view of a Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York
Ruler view of a Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York The smallest ruler marks are 1/16".
Acroneuria abnormis (Perlidae) (Golden Stone) Stonefly Nymph from Fall Creek in New York

This stonefly was collected from Fall Creek in New York on March 29th, 2006 and added to Troutnut.com by Troutnut on April 6th, 2006.

Discussions of this Nymph

Probably Acroneuria lycorias
1 replies
Posted by GONZO on Oct 10, 2006
Last reply on Oct 28, 2008 by GONZO
I've been staring at this one for quite some time. My first impression was lycorias (Boreal Stone, Giant Brown Stonefly). I'm pretty familiar with this species, but I don't know of a good key to Acroneuria at the species level.

The lack of a row of spinules along the occiput of the head and presence of postocular and pronotal fringes all say Acroneuria for sure.

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References

Acroneuria abnormis (Golden Stone) Stonefly Nymph Pictures

Collection details
Location: Fall Creek, New York
Date: March 29th, 2006
Added to site: April 6th, 2006
Author: Troutnut
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