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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
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.
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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This topic is about the Mayfly Genus Baetisca

These mayflies are a sleeper hatch which has barely received a nod in the fly fishing literature. Their abundance never matches that of the classic superhatches, but they can be important on some waters. The taxonomic common name for this family and genus is Armored Mayfly but angler reports often refer to them as Humpback Nymphs and the adults as Speckled Duns or Batflies.

Their primary claim to fame is their peculiar shape, both as nymphs and as adults. On most rivers they are a rare oddity, but there are places where their spinner falls elicit greedy rises and staunch selectivity from the trout. These spinners never even come close to blanketing the water, but trout have such an affinity for them that even their sparsest falls should excite the angler.

I favor two explanations for their importance. First, they have a very stout profile, and late-season beetle action suggests that trout like this trait. Second, the Baetisca action lasts for up to a month on a single stretch of water. This caters to the selective trout's love of the familiar.

Example specimens

BRAT
Posts: 10
BRAT on Oct 25, 2009October 25th, 2009, 8:46 am EDT
Hi there; I just gathered a sample from our local Black River here in SE Vermont, and found a thriving population of armored mayflies. Wasn't sure what they were at first, with their bubble-humped backs and short little tails, but once I used my hand lens I realized they have tiny little "thorns" behind their last legs. Their mottled coloring resembles everything I've seen here, confirming my ID. I'll be sending off a sample to a friendly bug lab to let the pros look at them.
Taxon
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on Oct 25, 2009October 25th, 2009, 8:54 am EDT
BRAT-

There are (11) species of Baetisca in N. America. Yours would likely be Baetisca rubescens if found in VT.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

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