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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Rhyacophila carolina (Green Sedge) Caddisfly Larva Pictures
This specimens shows that the name "green rockworm" doesn't quite fit all Rhyacophila larvae, even though it does fit the majority. This is actually the first of their larvae that I've found in a different color. I'm not sure if it's because of the species or because this is a young one, but I have found equally small green larvae, so I'm guessing it's the species.
This caddisfly was collected from Mongaup Creek in New York on May 6th, 2007 and added to Troutnut.com by Troutnut on May 18th, 2007.
Discussions of this Larva
carolina?
3 replies
Posted by Litobrancha on Jun 12, 2007
Last reply on May 16, 2011 by Peter_O
fits carolina in the key, but something doesn't look right to me, head shape doesn't really look like carolina and it is rather hairy. love to see an adult!!!
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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.
Rhyacophila carolina (Green Sedge) Caddisfly Larva Pictures
Collection details
Location: Mongaup Creek, New York
Date: May 6th, 2007
Added to site: May 18th, 2007
Author: Troutnut
Date: May 6th, 2007
Added to site: May 18th, 2007
Author: Troutnut