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.
|Option 1||Option 2|
|Occipital area with a pair of pale oval markings adjacent to compound eyes; posterior margins of ovals marked by dense irregular rows of short, thick setae (sf 16.173)||Occipital area without pale oval markings margined by short, thick setae|
|Western North America and higher latitudes of Eastern North America||Widely distributed|
5 Example Specimens
This specimen represents a common find in a late-April sample from the far upper Yakima River. It seems to be the same species as another one I collected previously. Of the species keyed in Szczytko & Stewart 1979, it probably matches Isoperla fusca closest, but there's a good chance it's a species that wasn't in the key. The leg segments have a fringe of fine hairs which is supposed to be absent in Isoperla fusca, and the four dark stripes of the mesonotum and metanotum don't continue as 4 separate stripes on the pronotum as they should in the description of fusca. It's possible fusca is more variable than previously described, or this is a different species not included in that key. It's also worth noting there's definitely no fringe of fine setae on any part of the cerci, just the whorls of little stout ones around segment bases.