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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.

Silver Creek in Idaho

Stream photos

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Zapada cinctipes (Tiny Winter Black) Stonefly NymphZapada 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.
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.

  1. Trout Streams
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  2. Washington
    3. ›
  3. Holder Creek

  1. Trout Streams
    2. ›
  2. Washington
    3. ›
  3. Holder Creek

I stopped along highway 18 east of Tiger Mountain and south of Fall City to collect some nymphs from this stream. It was simply a convenient spot to look for bugs (if scrambling down a steep, brushy, muddy slope counts as convenient). I have never heard of anyone fishing it. It seems too small and brushy to mess with, though it's large enough to probably hold small trout.

Closeup insects by Troutnut from Holder Creek in Washington

11
Calineuria californica (Golden Stone) Stonefly Nymph
Lateral view of a Calineuria californica (Perlidae) (Golden Stone) Stonefly Nymph from Holder Creek in Washington
This striking golden stonefly is the first of its species I've had the chance to photograph.
7
Male Baetis bicaudatus (BWO) Mayfly Nymph
Male Baetis bicaudatus (Baetidae) (BWO) Mayfly Nymph from Holder Creek in Washington
This specimen was collected along with a female which was quite a bit larger, different in color, but otherwise seemed the same morphologically.
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Taenionema (Willowfly) Stonefly Nymph
Taenionema (Taeniopterygidae) (Willowfly) Stonefly Nymph from Holder Creek in Washington
This specimen was the only one of its kind in my kick net sample from this small creek. At first I thought it was Nemouridae, but it's not. Unfortunately, there is no species key available for Taenionema nymphs. Potential species found in Washington include nigripenne, oregonense, pacificum, and pallidum.
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Female Baetis bicaudatus (BWO) Mayfly Nymph
Female Baetis bicaudatus (Baetidae) (BWO) Mayfly Nymph from Holder Creek in Washington
I collected this one along with a male that was quite a bit smaller but equally ready to emerge in mid April. I spent quite a while on the identifications, because they really don't look very much like the Baetis bicaudatus nymph I caught last year in Idaho. However, the presence of hind wing pads rules out Acentrella turbida and Iswaeon anoka, the lack of a fringe of long setae on the tibiae rules out Acentrella insignificans, range rules out Heterocloeon, and the thumb-like projection on the labial palp points to Baetis. Thus, Baetis bicaudatus is a fairly confident ID, and it's not too surprising that it looked different from my previous specimen because bicaudatus is thought to be a species complex with multiple types that haven't been fully sorted out yet. The microscope pictures for this specimen aren't from the same exact nymph, but a mixture of a few others of the same kind that I didn't mind dissecting.

References

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