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.
To my knowledge, this species has only been described in the scientific literature from the Oregon Cascades. However, on July 25th, I found several swarms of a dozen or so male spinners dancing above a gravel road/trail on the rim of a bouldery canyon at 2800 feet elevation on the eastern slope of the Washington Cascades.
Although this canyon would easily constitute class 4+ whitewater when flows are higher, at typically low summer flows there are lots of quiet backwaters in the pools between the fast drops and boulders. This might be the habitat for the Paraleptophlebia nymphs.
I found them again a couple weeks later on the Middle Fork Snoqualmie River on the west slope of the Washington Cascades.
Spinner behavior
The male spinners I encountered were flying right at dusk.
Specimens of the Mayfly Species Paraleptophlebia sculleni
This specimen (and a few others I collected but didn't photograph) appear to represent the first finding of Paraleptophlebia sculleni outside the Oregon Cascades, although it is not a monumental leap from there to the Washington Cascades. The key characteristics are fairly clear.
For a species not yet reported in my state, I've been surprised to find these in two different locations lately. I was tempted to think they're the more common Paraleptophlebia debilis, but the characteristic big dorsal bump on the claspers just isn't present.
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