Mayfly Genus Neoephemera

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Neoephemeridae

» Genus Neoephemera

4 species aren't included.

Pictures Below ↓

To my knowledge, nothing has been written in the angling literature about this rare genus of relatively large mayflies.

Where & When

Region: East

Neoephemera seems to be most common in the Southeast, although there are scattered distribution records across parts of the Midwest and Northeast. The one specimen on this site hatched in mid-late May.

Nymph Biology

Neoephemera mayfly nymphs look like overgrown Caenis nymphs, with the characteristic operculate (

The operculate gills of a Caenis nymph.

Operculate: Lidlike; usually used to describe the pair of enlarged elytroid gills (called the operculum) which some silt-dwelling mayfly nymphs like Caenis and Eurylophella have developed to shield their other gills from debris.) gills protecting their other gills from silt.

Pictures of 1 Mayfly Specimen in the Genus Neoephemera:

Neoephemera Mayfly Nymph

View 7 PicturesThis specimen was sent to me for identification by Caleb Boyle, who did such a good job taking pictures of his mystery mayfly that, after identification, I asked him for permission to add it to this site, which he granted. This is great luck, since Neoephemera is a rare mayfly and it's unlikely I would ever have collected a specimen for the site myself.

Caleb collected it in mid-late May of 2004 either McDowell County or Ashe County in North Carolina, in a riffle less than two feet deep in a cold trout stream. He reared the nymph into a dun, whose wings appear in one of the photos below. He describes the specimen as follows:

Nymph exoskeleton:
Body: 16-17mm
Tails: 3, equal length, 13mm
Found on the surface of the water. The gill cover covers ab. segments 3-5.

Subimago (Subimago: Mayfly nymphs emerge from the water into subimagoes, better known to anglers as "duns." They are a sexually immature, winged, recognizably adult stage and they must molt one more time into imagoes or "spinners" before they can mate.):
Body: 16mm, dark brown/ olive
Tails: 3, equal length, 14mm
Wings: dark slate color, large hind wings.

I don't know to which species it belongs, but its size rules out the most common one in the genus, Neoephemera bicolor. It matches the size of Neoephemera purporea so that is a likely other possibility, but there are two other candidate species (Neoephemera compressa and Neoephemera youngi) about which I have no information, so I can't rule them out.

Disregard the camera, region, and exact date listed on these photos. I still need to update the site to accommodate user contributions which don't use my equipment.

Collected May 20, 2004 from unknown in North Carolina
Added to Troutnut.com by Troutnut on March 20, 2007

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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.

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).

The operculate gills of a Caenis nymph.

Subimago: Mayfly nymphs emerge from the water into subimagoes, better known to anglers as "duns." They are a sexually immature, winged, recognizably adult stage and they must molt one more time into imagoes or "spinners" before they can mate.