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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

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.
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Male Baetidae (Blue-Winged Olive) Mayfly Nymph Pictures

This male nymph is probably in its final instar. The wing pads are extremely black and the large turbinate eyes are very apparent inside the nymph's head.

Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Ventral view of a Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Lateral view of a Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Male Baetidae (Blue-Winged Olive) Mayfly Nymph from the Bois Brule River in Wisconsin
Dorsal view of a Male Baetidae (Blue-Winged Olive) 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

Nymph Color Comment
8 replies
Posted by DarkDun on Jan 30, 2007
Last reply on Jul 18, 2009 by Shawnny3
I see the grayish tint as more of a Salmon tint. I would tie up some variations and test them. I tie all my nymphs with a variegated coloration rather than a blend. This works on most flies and I try to match the tones to the segment(band)of the natural as you sugested. I have had much success with this approach.
Baetid nymph color
1 replies
Posted by Martinlf on Dec 23, 2006
Last reply on Dec 26, 2006 by GONZO
OK, this olive nymph seems to have a good bit of grey in it. I know colors vary a lot among baetids, but I'm wondering about a good general color for shucks. And nymphs. Are most of them more olive than this? Or is it too hard to generalize? Also, I notice darker and lighter segments in the abdomen. I've noted this in subvaria's and try to get a lighter band just ahead of the darker tail segment in nymphs I tie for them. Perhaps this is a good idea with baetid nymphs as well.

Start a Discussion of Nymph

Male Baetidae (Blue-Winged Olive) Mayfly Nymph Pictures

Collection details
Location: Bois Brule River, Wisconsin
Date: June 9th, 2005
Added to site: May 26th, 2006
Author: Troutnut
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