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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.

Lateral view of a Female Sweltsa borealis (Chloroperlidae) (Boreal Sallfly) Stonefly Adult from Harris Creek in Washington
I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing this one.
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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Ephemerella invaria (Sulphur) Mayfly Nymph Pictures

This small Ephemerella invaria nymph was at least a month away from emergence.

Ruler view of a Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York The smallest ruler marks are 1 mm.
Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Dorsal view of a Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
Ventral view of a Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York

This mayfly was collected from the Beaverkill River in New York on April 19th, 2006 and added to Troutnut.com by Troutnut on April 21st, 2006.

Discussions of this Nymph

Invaria nymph
18 replies
Posted by Martinlf on Dec 23, 2006
Last reply on Nov 30, 2009 by Oldredbarn
OK, the invaria nymph shows the same lighter darker dorsal bandsand the solid dark ventral color on the abdomen as the subvaria, though its size makes me wonder if it is immature and may darken. For many considering this kind of detail will be superfluous, but for some of us nuts who like to fritter away the hours considering the possible uses of such information, this may confirm the claims of those who like to leave streaks in when blending fur, or perhaps even the claims of Caucci and Nastasi who promote a spectrumized dubbing.

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Ephemerella invaria (Sulphur) Mayfly Nymph Pictures

Collection details
Location: Beaverkill River, New York
Date: April 19th, 2006
Added to site: April 21st, 2006
Author: Troutnut
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