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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Caddisfly Genus Oxyethira (Cream and Brown Microcaddisflies)
Every stage of this widespread, tiny but abundant genus may be important.
Genus Range
Larva & pupa biology
Current speed: Still or slow
Substrate: Vegetation
Discussions of Oxyethira
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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.
- Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.
Caddisfly Genus Oxyethira (Cream and Brown Microcaddisflies)
Taxonomy
36 species (Oxyethira abacatia, Oxyethira aculea, Oxyethira aeola, Oxyethira allagashensis, Oxyethira anabola, Oxyethira araya, Oxyethira arizona, Oxyethira coerceus, Oxyethira dualis, Oxyethira dunbartonensis, Oxyethira ecornuta, Oxyethira elerobi, Oxyethira florida, Oxyethira forcipata, Oxyethira glasa, Oxyethira grisea, Oxyethira itascae, Oxyethira janella, Oxyethira kelleyi, Oxyethira kingi, Oxyethira lumipollex, Oxyethira lumosa, Oxyethira maya, Oxyethira mirabilis, Oxyethira novasota, Oxyethira obtatus, Oxyethira parce, Oxyethira rivicola, Oxyethira roberti, Oxyethira rossi, Oxyethira savanniensis, Oxyethira setosa, Oxyethira sida, Oxyethira sininsigne, Oxyethira verna, and Oxyethira zeronia) aren't included.