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.

Stream photos

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Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult

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.

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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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Stonefly Genus Amphinemura (Tiny Winter Blacks)

Where & when

In 96 records from GBIF, adults of this genus have mostly been collected during May (36%), April (27%), and June (26%).

In 9 records from GBIF, this genus has been collected at elevations ranging from 480 to 3264 ft, with an average (median) of 2917 ft.

Genus Range

source

Map of specific collection sites

Specimens of the Stonefly Genus Amphinemura

1 Female Adult

Female Amphinemura (Tiny Winter Black) Stonefly Adult

6 Pictures

Lateral view of a Female Amphinemura (Nemouridae) (Tiny Winter Black) Stonefly Adult from Mystery Creek #23 in New York

A few of these tiny stoneflies were among the only species of aquatic insect adults in the air on this particular afternoon, with most of the action coming from a species of Epeorus mayfly. I somehow forgot to photograph this one on the usual ruler, but I recall it was very, very small, with an abdomen no more than 1mm in girth and the body, not counting the wings, probably just 5-7mm long.

Collected September 5, 2006 from Mystery Creek #23 in New York

Added by Troutnut on October 3, 2006

Collected September 5, 2006 from Mystery Creek #23 in New York and added by Troutnut on October 3, 2006

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