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.

Waterfalls over smooth bedrock above Titcomb Lakes

From Titcomb Basin in Wyoming

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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Updates from October 4, 2011

Closeup insects by Bnewell from the Touchet River in Washington

Onocosmoecus unicolor (Great Late-Summer Sedge) Caddisfly Adult

2 Pictures

Onocosmoecus unicolor (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Adult from the Touchet River in Washington

Collected October 4, 2011 from the Touchet River in Washington

Added by Bnewell on October 11, 2011

Collected October 4, 2011 from the Touchet River in Washington and added by Bnewell on October 11, 2011

Male Paraleptophlebia bicornuta (Mahogany Dun) Mayfly Dun

1 Picture

Male Paraleptophlebia bicornuta (Leptophlebiidae) (Mahogany Dun) Mayfly Dun from the Touchet River in Washington

You wonder sometimes how certain insects get their common names. This one is called the 'mahogany dun' for some unknown reason.

Collected October 4, 2011 from the Touchet River in Washington

Added by Bnewell on October 6, 2011

Collected October 4, 2011 from the Touchet River in Washington and added by Bnewell on October 6, 2011

Comments / replies

Entoman

Northern CA & ID

Posts: 2604

Entoman on Oct 6, 2011October 6th, 2011, 9:09 am EDT

Hi Bob,

You wonder sometimes how certain insects get their common names. This one is called the 'mahogany dun' for some unknown reason.

Yeah, I agree with you that Blue Quill (defined as a dun hackled, peacock quill bodied fly) is a better handle for this specimen. As to why it's stuck with the name Mahogany Dun, I'm afraid it is a victim of lumping as important species of leptophlebiids are mahogany colored. Important baetids go by the name Blue-Winged Olive in spite of having brown bodies for the same unfortunate reason.

Regards,

Kurt

"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman