Mayfly Species Ephemerella aurivillii

Mayflies

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Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)

» Genus Ephemerella (Hendricksons, Sulphurs, PMDs)

» Species aurivillii

Pictures Below ↓

I have found nothing about this species in the writing of anglers, but the scientific literature shows it to be the most widespread species in the Ephemerella genus, and the only one that spans more than one continent. It may have gone unnoticed for so long because it might not produce thick hatches, and the sporadic individuals could easily be mistaken for Hendricksons.

Where & When

Regions: East, Midwest, West

Time Of Year (?): Mid-June to early August

This species was first described in Europe, and has also been found in Asia and North America. I have collected them in Alaska and New York, and probably Wisconsin, although the ID on the Wisconsin specimens is less certain.

I found ready-to-hatch, definitive Ephemerella aurivillii nymphs near Fairbanks, Alaska, in mid-July. However, because this species is found across such a large geographic range, the emergence timing probably varies widely. They may go unnoticed in the East due to overlaps in timing with more abundant Ephemerella species.

Pictures of 21 Mayfly Specimens in the Species Ephemerella aurivillii:

Specimen Page:12 3

Male Ephemerella aurivillii Mayfly Spinner

View 15 PicturesThis spinner molted from a dun after being photographed, and the dun form is listed here as a separate specimen. I've rarely found a more cooperative and photogenic mayfly.

Collected July 10, 2011 from Nome Creek in Alaska
Added to Troutnut.com by Troutnut on July 16, 2011

Male Ephemerella aurivillii Mayfly Dun

View 14 PicturesThis is the most widespread species of Ephemerella, and also the most abundant in some places, but nobody I've talked to seemed to know what its duns looked like, and there were no pictures of its duns online or in any angling books. That mystery is solved with this male dun, which hatched from a definitively identified nymph.

Collected July 10, 2011 from Nome Creek in Alaska
Added to Troutnut.com by Troutnut on July 12, 2011

Ephemerella aurivillii Mayfly Nymph

View 7 Pictures

Collected May 10, 2008 from the Chena River in Alaska
Added to Troutnut.com by Troutnut on April 20, 2011

Specimen Page:12 3

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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.

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).

Spinner: There are two winged stages of adult mayflies. They emerge from the water as duns, molt on land (usually) into their fully mature stage, spinners. As spinners, they mate, lay eggs, and die.