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.
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It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.
I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.
The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.
Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.
The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.
Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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Dark Olive Brown Spinners
Like most common names,"Dark Olive Brown Spinner" can refer to more than one taxon. They're previewed below, along with 1 specimen. For more detail click through to the scientific names.
Mayfly Species Baetis flavistriga
These are very rarely called Dark Olive Brown Spinners.
This is one of the most widespread and abundant Baetis species, and it may produce fishable hatches under a variety of conditions.
This species is known in angling books by several old synonyms, including Baetis quebecensus, Baetis levitans, Baetis cingulatus, and Baetis phoebus, in addition to the correct name.
This species is known in angling books by several old synonyms, including Baetis quebecensus, Baetis levitans, Baetis cingulatus, and Baetis phoebus, in addition to the correct name.
This nymph keys to Baetis assuming the villipore is present (hard to see in my photos or scope), and within that genus it tentatively keys to the flavistriga species complex, of which Baetis flavistriga itself is by far the most common in Washington state, so that's the most likely ID.
See 2 more specimens...
Mayfly Species Dannella simplex
These are very rarely called Dark Olive Brown Spinners.
Although by no means a superhatch, this species can be important. Authors who discuss it lament the general lack of credit it receives for the fine hatches it produces on some streams.