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3. Acentrella insignificans nymphs

Acentrella insignificans nymphs are abundant in the Russian River from early January through April. Most are found in riffles or at the edge of riffles, also found in lesser numbers in glides. They prefer a substrate of clean gravel and cobble. Large numbers of nymphs are often found on the underside of cobbles.
The nymphs were identified to genus using Merritt, Cummins and Berg (2008). They were identified to species using Morihara and McCafferty's "The Baetis Larvae of North America (Ephemeropttera:Baetidae) (1979). They are listed in this account under the synonym Baetis insignificans. http://www.ephemeroptera-galactica.com/pubs/pub_m/pubmoriharad1979p139.pdf I also used Jacobus and McCafferty's key for North American Acentrella larvae in "A new species of Acentrella Bergsstrom (Ephemeroptera:Baetidae) from Great Smoky Mountains National Park, USA" (2006).http://www.ephemeroptera-galactica.com/pubs/pub_j/pubjacobusl2006p101.pdf