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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I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing this one.
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Mayfly Family Caenidae (Angler's Curses)
The tiny mayflies of this family are usually found in warm, slow, marginal trout water, although some trout streams hold good populations too.
The only genus ever known to produce fishable hatches is Caenis. It turns up frequently for anglers who sample nymphs, but it is rarely of any practical importance for fly fishing because its emergence traits and tiny size (even smaller than Tricorythodes) make it relatively unimportant.
Brachycercus is even more focused on warm water than Caenis.
The only genus ever known to produce fishable hatches is Caenis. It turns up frequently for anglers who sample nymphs, but it is rarely of any practical importance for fly fishing because its emergence traits and tiny size (even smaller than Tricorythodes) make it relatively unimportant.
Brachycercus is even more focused on warm water than Caenis.
Taxonomic History
Some relatively common trout stream species formerly known in Brachycercus were recently reclassified into Sparbarus and Susperatus.
Family Range
Identification
To determine whether a specimen of Ephemeroptera belongs to Caenidae, use the Key to Families of Mayfly Nymphs or Key to Families of Mayfly Duns and Spinners.
Specimens of the Mayfly Family Caenidae
1 Female Dun
1 Female Spinner
9 Nymphs
This interesting little Caenis nymph is way darker than any of the others I collected in January 2004, probably a different species. It also has shorter tails.
I confirmed the identity of this nymph by looking at it under a microscope to be certain of the shape of its gills and head.
I confirmed the identity of this nymph by looking at it under a microscope to be certain of the shape of its gills and head.
I confirmed the identity of this nymph by looking at it under a microscope to be certain of the shape of its gills and head.
I confirmed the identity of this nymph by looking at it under a microscope to be certain of the shape of its gills and head.
This is probably the most common lake mayfly in western Montana. It can be found with one or more species of Caenis.
Discussions of Caenidae
Start a Discussion of Caenidae
References
- Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.
Mayfly Family Caenidae (Angler's Curses)
Taxonomy
Genus in Caenidae: Brachycercus, Caenis
5 genera (Amercaenis, Cercobrachys, Latineosus, Sparbarus, and Susperatus) aren't included.