Header image
Enter a name
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.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Goose
Posts: 77
Goose on Sep 18, 2006September 18th, 2006, 1:47 am EDT
Hi Jason: Being that the bottom side of a BWO is a medium to light olive in color, why do people tend tie them in dark olive or even gray? The fish only see the bottom. Just wondering.
Troutnut
Troutnut's profile picture
Administrator
Bellevue, WA

Posts: 2758
Troutnut on Sep 18, 2006September 18th, 2006, 7:08 am EDT
BWO colors really run the gamut, because they can belong to several dozen different mayfly species. Some are light and some are darker.

Patterns do seem to be a bit on the dark side. This might have something to do with the common name. People think "olive" should be the shade of a green olive, which is too dark for a lot of the species. Then the patterns get even darker when they're wet.

The effect might seem a little worse when you look at the pictures on this site, because I photograph mayflies under really bright light to show the hues and patterns well. Under normal conditions they'll look a bit darker than they appear in my photos.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Sayfu
Posts: 560
Sayfu on Mar 27, 2013March 27th, 2013, 1:23 pm EDT
A guide that I have always respected for his fly fishing knowledge, a Montana Guide who guided on the Missouri River, and a trib, the Smith river, Neal Streaks, wrote that his effective dry for BWO's was a gray bodied Parachute Adams. He didn't feel a need to match the exact body color.
JOHNW
JOHNW's profile picture
Chambersburg, PA

Posts: 452
JOHNW on Mar 27, 2013March 27th, 2013, 3:56 pm EDT
Goose,
In fishing many of the same streams as you I have found that fly rite #10 is a very good color for the early baetids, while something leaning more to the gray end of the spectrum is more suitable for the big summer BWO's (cornutas I believe). Although the ones I examined most recently were almost the same dun color as the wing.
JW
"old habits are hard to kill once you have gray in your beard" -Old Red Barn

Quick Reply

Related Discussions

Topic
Replies
Last Reply
10
Apr 2, 2013
by Feathers5
8
Jan 9, 2009
by JAD
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy