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 seems to lead to Couplet 35 of the Key to Genera of Perlodidae Nymphs and the genus Isoperla, but I'm skeptical that's correct based on the general look. I need to get it under the microscope to review several choices in the key, and it'll probably end up a different Perlodidae.
Millcreek on Sep 17, 2015September 17th, 2015, 2:25 pm EDT
These nymphs were identified to genus using Merritt, Cummins and Berg (2008) as well as Buglab's "Key to Western Baetidae". They were keyed to species using Day's "New Genera of Mayflies From California" 1955, http://www.ephemeroptera-galactica.com/pubs/pub_d/pubdayw1955p121.pdf where it is described as Paracloeodes abitus (a synonym of Paracloeodes minutus). These were found in the Russian River, CA.
It's found in warm shallow water with a substrate of small gravel with a medium amount of algae attached. It's usually found in September.
The main ways of telling it apart from the other Baetidae are smaller size (3.5 - 4 mm), the claws being half the length of the tarsi and a labium shaped as shown above.
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