The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
I haven't keyed this specimen out, but I am instead placing it in Hydropsyche based on the striking visual similarity to this one, which I did key out.
This caddisfly was collected from the Madison River in Montana on June 30th, 2019 and added to Troutnut.com by Troutnut on July 17th, 2019.