The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
This genus has not received any credit in angling books I've read, but entomologist Jason Robinson writes on the Troutnut forum that Agapetus is a common trout stream genus.
It is very easy for caddisflies to go unnoticed in the angling world, because they may be so easily mistaken for already well-known species by anglers with limited identification resources and tools.
Where & when
In 199 records from GBIF, adults of this genus have mostly been collected during June (29%), May (28%), July (18%), August (11%), and April (6%).
In 85 records from GBIF, this genus has been collected at elevations ranging from 69 to 20669 ft, with an average (median) of 2021 ft.