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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This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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Cheumatopsyche (Little Sister Sedge) Caddisfly Pupa Pictures
I photographed this one recently dead. It's hard to keep caddis pupae alive for very long in a collection container.
This caddisfly was collected from the Namekagon River in Wisconsin on May 18th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.
Discussions of this Pupa
Can you provide a size for this specimen?
5 replies
Posted by GONZO on Nov 8, 2006
Last reply on Jul 24, 2008 by GONZO
Jason-
I hate to ask you to dig through your specimen vials, but I'm curious to know if you can give a size reference for this one. I've stared at it many times. My first impression was Brachycentrus, but that impression was based entirely on color and markings. I haven't been able to find any definitive keys to verify this id (though I may be missing something).
May 18 does seem a little on the late side for most of the common Eastern/Midwestern Brachycentrus spp. But, we do have a peak emergence of a Micrasema sp. around that time on the Brodheads. This is the reason I was wondering about the size. I also wanted to call attention to this specimen in the hope that Litobrancha, Taxon, or someone else might be able to end my puzzlement.
I hate to ask you to dig through your specimen vials, but I'm curious to know if you can give a size reference for this one. I've stared at it many times. My first impression was Brachycentrus, but that impression was based entirely on color and markings. I haven't been able to find any definitive keys to verify this id (though I may be missing something).
May 18 does seem a little on the late side for most of the common Eastern/Midwestern Brachycentrus spp. But, we do have a peak emergence of a Micrasema sp. around that time on the Brodheads. This is the reason I was wondering about the size. I also wanted to call attention to this specimen in the hope that Litobrancha, Taxon, or someone else might be able to end my puzzlement.
Start a Discussion of Pupa
References
- Merritt R.W., Cummins, K.W., and Berg, M.B. 2019. An Introduction to the Aquatic Insects of North America (Fifth Edition). Kendall/Hunt Publishing Company.
Cheumatopsyche (Little Sister Sedge) Caddisfly Pupa Pictures
Collection details
Location: Namekagon River, Wisconsin
Date: May 18th, 2004
Added to site: January 25th, 2006
Author: Troutnut
Date: May 18th, 2004
Added to site: January 25th, 2006
Author: Troutnut