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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Snow Sedges
This common name refers to only one genus. Click its scientific name to learn more.
Caddisfly Genus Psychoglypha
These are often called Snow Sedges.
These caddisflies may be important to the winter angler because they are one of the only insects around. Gary LaFontaine relays an interesting correspondence about this genus in Caddisflies:
I will keep an eye out this winter and hopefully collect some specimens to photograph.
Dr. George Roemhild explained to me how he finds these winter caddisflies in February and March: "They crawl up on the snowbanks, but when the sun hits their dark wings they melt down out of sight. That's how I collect them, by walking along looking for holes in the snow."
I will keep an eye out this winter and hopefully collect some specimens to photograph.
This Psychoglypha adult was found clinging to my garage door in the evening on April 9, 2013. It measures 21 mm in length, from the front of head to the end of wings. It is my hope that Creno will be able to identify it to species based on the image of its genitalia. However, if other images are required for a species ID, the specimen is available, so they can be easily taken. Thanks, Roger Rohrbeck, Mercer Island, WA.
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References
- LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
- 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.