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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Male Ephemerella subvaria (Hendrickson) Mayfly Dun Pictures
I collected this male Hendrickson dun and a female in the pool on the Beaverkill where the popular Hendrickson pattern was first created. He is descended from mayfly royalty.
This mayfly was collected from the Beaverkill River in New York on April 19th, 2006 and added to Troutnut.com by Troutnut on April 22nd, 2006.
Discussions of this Dun
My First Hendrickson Hatch
1 replies
Posted by MarkP on May 19, 2012
Last reply on May 22, 2012 by Entoman
Got to experience my first hatch of these flies on a stream where they aren't listed as having them present. Didn't last too long. Took place at 9:30 am and lasted about 30 minutes. Fish didn't rise to them during the hatch but I couldn't keep them off of a #18 BWO later in the day.
Unit of Measure
Posted by Flybyknight on Jan 11, 2008
Last reply on Jan 11, 2008 by Flybyknight
Look at the ruler. There are 10 clicks to a number.
I believe that we are looking at millimeters, not inches,
IMHO.
Dick
I believe that we are looking at millimeters, not inches,
IMHO.
Dick
Hendrickson size
2 replies
Posted by Jpsully on Jan 10, 2007
Last reply on Mar 16, 2007 by Matokuwapi
Jason:
Looking at the fifth photo from the top (the one with the ruler under the fly), it would appear that if you were to rotate the fly just a bit to the left, it would show that the fly is over one inch (25mm) long. That would make it twice as long as any Hendrickson I have ever seen. The average Hendrickson (to the best of my knowledge) is usually around 10-12mm (or about 1/2 inch), hook size 10-12. The hook size just doesn't seem to fit either. Where am I going wrong when looking at this fly (and hook)?
JP
Looking at the fifth photo from the top (the one with the ruler under the fly), it would appear that if you were to rotate the fly just a bit to the left, it would show that the fly is over one inch (25mm) long. That would make it twice as long as any Hendrickson I have ever seen. The average Hendrickson (to the best of my knowledge) is usually around 10-12mm (or about 1/2 inch), hook size 10-12. The hook size just doesn't seem to fit either. Where am I going wrong when looking at this fly (and hook)?
JP
Start a Discussion of Dun
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.
Male Ephemerella subvaria (Hendrickson) Mayfly Dun Pictures
Collection details
Location: Beaverkill River, New York
Date: April 19th, 2006
Added to site: April 22nd, 2006
Author: Troutnut
Date: April 19th, 2006
Added to site: April 22nd, 2006
Author: Troutnut