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.
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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.
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.
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This topic is about the Caddisfly Genus Pycnopsyche
Example specimens
BrettB on Oct 2, 2008October 2nd, 2008, 7:16 am EDT
Came in to work today and noted several large Autumn sedges on doors facing river(18mm wing-to-head and 34mm total w/ antennae). Though more brownish-rusty than I remember them being, I'm relatively certain it is a Pycnopsyche due to the size, timing and dark markings near the rear mid-wing (sort of looks like a yin-yang symbol). Does anyone know of a good emerger fly for this hatch? I'm assuming it emerges in the evening through early morning. I may tie up some size 8 rusty elk hair caddis for adult imitations. Big bugs!
Brett Billings
long-time tyer and amateur entomologist
long-time tyer and amateur entomologist
GONZO on Oct 2, 2008October 2nd, 2008, 7:54 am EDT
Brett,
Although some might emerge on the surface, most Pycnopsyche crawl out to emerge. A surface emerger is usually not of much value. A large fur-bodied soft hackle crawled along the bottom toward shore can be effective for imitating the pupae. In addition to the dry adult pattern, a big rusty wet could also be useful when the adults are laying eggs.
Although some might emerge on the surface, most Pycnopsyche crawl out to emerge. A surface emerger is usually not of much value. A large fur-bodied soft hackle crawled along the bottom toward shore can be effective for imitating the pupae. In addition to the dry adult pattern, a big rusty wet could also be useful when the adults are laying eggs.
BrettB on Oct 3, 2008October 3rd, 2008, 9:35 am EDT
Gonzo,
Thanks for the ideas. I like the idea of a big, fat wet fly on the bottom late in the afternoon as nymphs start to drift. A big wet fly in size 10 or 12? Perhaps some grey-brown muskrat fur with partridge hackle? Sounds like a very promising technique. The rusty wet fly also sounds good.
Thanks for the ideas. I like the idea of a big, fat wet fly on the bottom late in the afternoon as nymphs start to drift. A big wet fly in size 10 or 12? Perhaps some grey-brown muskrat fur with partridge hackle? Sounds like a very promising technique. The rusty wet fly also sounds good.
Brett Billings
long-time tyer and amateur entomologist
long-time tyer and amateur entomologist
GONZO on Oct 3, 2008October 3rd, 2008, 9:49 am EDT
I'd go lighter with the body color on the pupa, Brett. The belly is usually a pale creamy color with a ginger tint and the back is a darker ginger-brown. A loose mix of those colors will suffice for a general suggestion. You might want to dub a band of blackish brown just behind the soft-hackle collar to suggest the dark wingpads. A #10-12 (2X) should be about right.
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