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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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Posts: 4
Fgfg on Feb 25, 2017February 25th, 2017, 12:01 pm EST
Hey 👋
I've been fishing clear creek in golden Colorado, waters icy, I've been out past two days. Swinging black, olive and white streamers. Poison tounges, black beauties and zebra midges - no hits.

Any special advice for Colorado Rocky Mountain frozen creeks?

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Posts: 148
Iasgair on Feb 25, 2017February 25th, 2017, 1:53 pm EST

Nice to see another Coloradan. For Clear Creek, the hatches will primarily be midges. But mayfly nymphs should be on the move as well. You may want to try a combination of these in a 2-nymph set up.

BH Pheasant tail sizes 16-20.
BH Brassie 18-22 in olive, cream, or gray.
BWO Para. 16-22.
Midge dry flies 20-28.

I hope this helps. I know it works well on the Big T.

Also, stay warm and please be careful on any ice. Most of all, be patient. They will be deep in holes, and tucked up tight under rocks. Clear Creek can be very tough this time of year, but obviously better after run off.

If you continue using streamers, keep them as close to the bottom as you can tapping the rocks.

Posts: 4
Fgfg on Feb 25, 2017February 25th, 2017, 2:01 pm EST
This post was more than helpful - thank you Isagair - I will keep you posted on what works ! Thanks again! @isadair
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Posts: 148
Iasgair on Feb 26, 2017February 26th, 2017, 1:23 am EST
One more thing. Use smaller streamers than what you would normally use. I would use something 1 1/2 inches long at most.

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Posts: 1776
PaulRoberts on Feb 26, 2017February 26th, 2017, 3:04 am EST
If you are in really cold water the fish may not be willing to move much. I know we've had an unseasonably warm February, but this last front has dropped temps back to winter. Keeping speed in check will become important again.

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