Chocolate Spinners

Mayflies

Caddisflies

Stoneflies

Scientific Names

Match	Scientific Name
	Eurylophella bicolor
	Ephemerella needhami

Like most common names, "Chocolate Spinner" can refer to more than one taxon. They're previewed below, along with 2 specimens. For more detail click through to the scientific names.

Mayfly Species Eurylophella bicolor

These are sometimes called Chocolate Spinners.

According to the Leonards in Mayflies: An Angler's Study of Trout Water Ephemeroptera , this species and Eurylophella bicolor are the two most likely hatches for fly fishermen to encounter in Michigan. Based on my sampling, it seems other species may be more prevalent elsewhere.

Mayfly Species Ephemerella needhami

These are sometimes called Chocolate Spinners.

This small and slightly noteworthy mayfly appears during the finest hours of the year. Ernest Schwiebert describes an Ephemerella needhami day in Matching the Hatch:

"It was a wonderul morning, with a sky of indescribable blue and big, clean-looking cumulus clouds, and the water was sparkling and alive. You have seen the water with that lively look; you have also seen it dead and uninviting in a way that dampens the enthusiasm the moment you wade out into the current."

I have not fished a needhami emergence, but the exquisite nymphs show up often (though never abundantly) in my samples.

Ephemerella needhami (Little Dark Hendrickson) Mayfly Nymph

View 5 PicturesI took quite a few notes at the microscope when I collected this specimen. They're attached to the appropriate pictures.

I found this specimen in the same collection as a similar one. Since I only have strange views of this one, it's possible that they're actually the same specimen and I somehow confused my picture-ordering and got the impression that they're different nymphs.

Collected June 8, 2005 from in
Added to Troutnut.com by on May 26, 2006

Ephemerella needhami (Little Dark Hendrickson) Mayfly Dun

View 7 PicturesSee the comments for an interesting discussion of the identification of this dun.

Collected June 1, 2007 from in
Added to Troutnut.com by on June 4, 2007

See 7 more specimens...

Jargon Defined:

Dun: Mayflies have two adult stages. They first emerge from the water as duns (scientifically known as the subimago stage). They then molt into the spinner (imago) stage, in which they mate and die. Sometimes the word "dun" is confusingly used to refer to a brownish gray color in fly tying materials.

Emergence: The transformation of a nymph or pupa into the adult winged stage of an insect. The term may refer to the emergence of an individual, or the daily or yearly event in which all individuals of a species emerge.

Nymphs: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).

Useful References:

Knopp, Malcolm and Robert Cormier. 1997. Mayflies: An Angler's Study of Trout Water Ephemeroptera . The Lyons Press.

Schwiebert, Ernest G. 1955. Matching the Hatch. MacMillan Publishing Company.