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 Cheumatopsyche (Little Sister Sedges)
To generalize broadly, Cheumatopsyche is found lower in the watershed than the similar genera Hydropsyche and Ceratopsyche. It is also smaller, but there is wide variation in size and color between the species. See the family Hydropsychidae page for life cycle details common to these genera.
The most important trout stream species are Cheumatopsyche campyla and Cheumatopsyche pettiti.
The most important trout stream species are Cheumatopsyche campyla and Cheumatopsyche pettiti.
Where & when
In 1233 records from GBIF, adults of this genus have mostly been collected during June (28%), July (22%), May (17%), August (15%), April (7%), and September (7%).
In 444 records from GBIF, this genus has been collected at elevations ranging from 10 to 9186 ft, with an average (median) of 2690 ft.
Genus Range
Specimens of the Caddisfly Genus Cheumatopsyche
1 Male Adult
I didn't identify this one directly, but I eventually identified one of several I collected from the same swarms that appeared to be of the same species. (I lost track of which specimen was which in storage.) The microscope pictures come from one of these specimen, not necessarily the same specimen as the DSLR pictures. They key to Cheumatopsyche, and the hind wing venation that separates them from Hydropsyche is pretty clear in the attached picture as well as another specimen I checked under the scope.
This specimen was one of tens of thousands we saw on a July 1st evening on the Madison, beginning with big swarms around every vehicle and tree at the Eight Mile Ford access point and continuing all up and down the river bank. We somehow didn't catch any trout, perhaps because they were stuffed with pupae from when these things emerged. Or maybe we just weren't fishing well. Either way, this one represents a major hatch there.
I somehow forgot to photograph this important specimen against the hooks size chart, but fortunately I preserved a few. The body length is about 6 mm, and total length from head to wingtip is 9 mm.
This specimen was one of tens of thousands we saw on a July 1st evening on the Madison, beginning with big swarms around every vehicle and tree at the Eight Mile Ford access point and continuing all up and down the river bank. We somehow didn't catch any trout, perhaps because they were stuffed with pupae from when these things emerged. Or maybe we just weren't fishing well. Either way, this one represents a major hatch there.
I somehow forgot to photograph this important specimen against the hooks size chart, but fortunately I preserved a few. The body length is about 6 mm, and total length from head to wingtip is 9 mm.
2 Female Adults
This one has a body a little bit over 6 mm long.
1 Adult
3 Pupae
This is the first fully formed caddis pupa (technically, a pharate adult) that I've collected and photographed alive and healthy. I'll put a video of this specimen online soon, too.
I photographed this one recently dead. It's hard to keep caddis pupae alive for very long in a collection container.
I was surprised how bright green this pupa is. It's chartreuse. After collecting it, I experimented with melting down chartreuse jigs and making little translucent rubber caddis abdomens on my flies. They looked good, and the trout liked them, but they weren't very durable at all. This specimen is recently deceased in the photographs.
Start a Discussion of Cheumatopsyche
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 Cheumatopsyche (Little Sister Sedges)
Taxonomy
Species in Cheumatopsyche
Cheumatopsyche campyla
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Cheumatopsyche etrona
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Cheumatopsyche gracilis
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Cheumatopsyche harwoodi
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Cheumatopsyche lasia
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Cheumatopsyche pasella
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Cheumatopsyche pettitiCaddisflies
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Cheumatopsyche sordida
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Cheumatopsyche speciosa
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Species in Cheumatopsyche: Cheumatopsyche campyla, Cheumatopsyche etrona, Cheumatopsyche gracilis, Cheumatopsyche harwoodi, Cheumatopsyche lasia, Cheumatopsyche pasella, Cheumatopsyche pettiti, Cheumatopsyche sordida, Cheumatopsyche speciosa
35 species (Cheumatopsyche analis, Cheumatopsyche aphanta, Cheumatopsyche arizonensis, Cheumatopsyche bibbensis, Cheumatopsyche burksi, Cheumatopsyche cahaba, Cheumatopsyche comis, Cheumatopsyche edista, Cheumatopsyche ela, Cheumatopsyche enonis, Cheumatopsyche flinti, Cheumatopsyche gelita, Cheumatopsyche geora, Cheumatopsyche gordonae, Cheumatopsyche gyra, Cheumatopsyche halima, Cheumatopsyche helma, Cheumatopsyche kinlockensis, Cheumatopsyche logani, Cheumatopsyche mickeli, Cheumatopsyche minuscula, Cheumatopsyche mollala, Cheumatopsyche morsei, Cheumatopsyche oxa, Cheumatopsyche parentum, Cheumatopsyche petersi, Cheumatopsyche pinaca, Cheumatopsyche pinula, Cheumatopsyche richardsoni, Cheumatopsyche rossi, Cheumatopsyche smithi, Cheumatopsyche vannotei, Cheumatopsyche virginica, Cheumatopsyche wabasha, and Cheumatopsyche wrighti) aren't included.