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 an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
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Caddisfly Genus Neophylax (Autumn Mottled Sedges)
In his tables in Caddisflies, Gary LaFontaine ranks this as the fourth most important genus in the Pacific Northwest, where the main species are Neophylax rickeri and Neophylax splendens, but other species may be important across the country. Swisher and Richards in Selective Trout say that Neophylax fuscus is very important in the Midwest.
Where & when
Neophylax caddisflies emerge in concentrated numbers in the fall because they enter diapause during the summer, which synchronizes their emergence to within three weeks on a given stretch of stream.In 150 records from GBIF, adults of this genus have mostly been collected during October (43%), September (27%), June (8%), July (7%), August (7%), and November (5%).
In 123 records from GBIF, this genus has been collected at elevations ranging from 30 to 8566 ft, with an average (median) of 1601 ft.
Genus Range
Egg-Laying behavior
The ovipositing behavior of this genus is not well-documented, but what is known varies by species.Specimens of the Caddisfly Genus Neophylax
1 Female Adult
This large caddisfly looks really neat close-up.
3 Larvae
The size of the head compared to the body in this larva is surprising, and I think this means it's a fairly early instar of something which is going to get a lot bigger, but I'm not sure.
See the forum comments for notes on the identification of this specimen.
2 Underwater Pictures of Neophylax Caddisflies:
A variety of cased caddisfly larvae, probably mostly Neophylax, have clustered along the backside of a rock in fast water. There seem to be some Helicopsychidae larvae clustered along the bottom, and a few other taxa are mixed in. It's interesting that several larvae have especially large stones placed over the front openings of their cases, perhaps to block the case off for pupation.
It does seem to be the wrong time of year for Neophylax to be pupating, but that was the ID given for one of these which I collected and photographed up close.
It does seem to be the wrong time of year for Neophylax to be pupating, but that was the ID given for one of these which I collected and photographed up close.
A wide variety of caddis larvae and other insects have clustered together on the backside of this rock in fast water.
In this picture: Caddisfly Genus Neophylax (Autumn Mottled Sedge).
Start a Discussion of Neophylax
References
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
- 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 Neophylax (Autumn Mottled Sedges)
Taxonomy
Species in Neophylax
Neophylax concinnus
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Neophylax fuscusSmall Dot-Wing Sedges
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Neophylax rickeriBrown Dot Sedges
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Neophylax splendens
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21 species (Neophylax acutus, Neophylax aniqua, Neophylax atlanta, Neophylax auris, Neophylax ayanus, Neophylax consimilis, Neophylax delicatus, Neophylax etnieri, Neophylax mitchelli, Neophylax nacatus, Neophylax occidentis, Neophylax oligius, Neophylax ornatus, Neophylax ottawa, Neophylax securis, Neophylax sinuatus, Neophylax slossonae, Neophylax smithi, Neophylax stolus, Neophylax toshioi, and Neophylax wigginsi) aren't included.