Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York

Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Stream photos

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Limnephilus (Summer Flier Sedge) Caddisfly Larva Limnephilus (Summer Flier Sedge) Caddisfly Larva

Case view of a Limnephilus (Limnephilidae) (Summer Flier Sedge) Caddisfly Larva from the Yakima River in Washington

This seems to be a young larva of Limnephilus. Although not clear in the picture, several ventral abdominal segments have chloride epithelia.

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27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.

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Baetis alius

Millcreek has attached these 4 pictures to aid in identification. The message is below.

Millcreek
Healdsburg, CA

Posts: 344

Millcreek on Jan 24, 2015January 24th, 2015, 1:07 pm EST

This mayfly was collected from the Russian River near Healdsburg, Ca. It's common from March through October. It's usually found in shallow water 3-12 inches deep and relatively free of silt with a bottom of sand, gravel and cobble.

It's fairly easy to identify from the dorsal side of the abdomen with section five, nine and ten being mostly light in color. It's also got a mouth with labial palpi having the inner margin of segment 2 slightly convex to nearly straight as opposed to variously concave. It also has the first gill much smaller than the others.

Descriptions to genus were from Merritt, Cummins and Berg (2008). The descriptions to species were from Morihara and McCafferty (1997) "The Baetis Larvae of North America (Baetidae: Ephemeroptera).
http://www.ephemeroptera-galactica.com/pubs/pub_m/pubmoriharad1979p139.pdf
and MacCafferty, Meyer, Randolph and Webb (2008) "Evaluation of Mayfly Species Originally Described as Baetis Leach (Ephemeroptera: Baetidae)From California.
http://www.ephemeroptera-galactica.com/pubs/pub_m/pubmccaffertyw2008p577.pdf

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