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.

The trees were leafing out and the trout were rising on this productive Wisconsin stream

From the Namekagon River in Wisconsin

Stream photos

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

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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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Acroneuria carolinensis (Golden Stone) Stonefly Nymph Pictures

This stonefly was collected from unknown in Wisconsin on February 7th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.

Discussions of this Nymph

Acroneuria specimen moved from genus to species level

Posted by Entoman on Mar 11, 2012

Last reply on Mar 11, 2012 by Entoman

The head markings better match up with A. carolinensis (pronounced unbroken W, thick tapering occipital band). Another clue is the femora maculation. A. abnormis usually has either dark brown legs without obvious maculation or longitudinal dark stripes as opposed to the pale bands or blotches evidenced on this specimen. While a dark dorsal habitus is usually associated with abnormis, it is not a very dependable character. The other common species (lycorias) has head and leg markings that can look quite similar, but it has anal gills and usually a pale center with dark margins on the terga.

A. carolinensis
http://bugguide.net/node/view/515177

A. abnormis
http://www.troutnut.com/specimen/446

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