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.

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Coleoptera (Beetle) Insect Larva Coleoptera (Beetle) Insect Larva

Lateral view of a Coleoptera (Beetle) Insect Larva from Sears Creek in Washington

6 Recently Added Photos

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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Stenonema vicarium (March Brown) Mayfly Nymph Pictures

I keyed this nymph to Stenonema fuscom, which is now synonymized with Maccaffertium vicarium. However, the size, markings, and time of year make me very skeptical of this identification.

Ruler view of a Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Nymph from the Bois Brule River in Wisconsin

Dorsal view of a Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Nymph from the Bois Brule River in Wisconsin

Ventral view of a Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Nymph from the Bois Brule River in Wisconsin

This mayfly was collected from the Bois Brule River in Wisconsin on June 9th, 2005 and added to Troutnut.com by Troutnut on May 26th, 2006.

Discussions of this Nymph

M. vicarium?

8 replies

Posted by Entoman on Mar 26, 2012

Last reply on Jul 2, 2012 by Gutcutter

You were right about the markings, Jason. This is one of the paler Summer Cahill species, probably mexicanum. The inverted "U" tergal markings are very distinctive (moved to mexicanum).

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