Pale Morning Duns
This name used to refer to two now defunct species, Ephemerella inermis and Ephemerella infrequens. The inermis mayflies were discovered to be the same species as Ephemerella excrucians and now they bear that scientific name. The infrequens species was recently reclassified as a subspecies (Subspecies: Entomologists sometimes further divide a species into distinct groups called subspecies, which have two lower-case words on the end of their scientific name instead of one. The latter is the sub-species name. For example, Maccaffertium mexicanum mexicanum and Maccaffertium mexicanum integrum are two different subspecies of Maccaffertium mexicanum.) of Ephemerella dorothea.
Anglers usually shorten the Pale Morning Dun hatch to the PMD hatch.
Like most common names, "Pale Morning Dun" can refer to more than one taxon. They're previewed below, along with 4 specimens. For more detail click through to the scientific names.
Mayfly Species Ephemerella excrucians
The behavioral information I've given below is tentative. Because of the taxonomic shuffling and the fact that books usually describe this species together with others, it is a little bit unclear which writings specifically apply to excrucians.
View 5 PicturesI spent (Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.) a while with a microscope to fairly positively identify this specimen as Ephemerella excrucians.Mayfly Species Ephemerella dorothea
Ephemerella dorothea consists of two distinct subspecies (Subspecies: Entomologists sometimes further divide a species into distinct groups called subspecies, which have two lower-case words on the end of their scientific name instead of one. The latter is the sub-species name. For example, Maccaffertium mexicanum mexicanum and Maccaffertium mexicanum integrum are two different subspecies of Maccaffertium mexicanum.) which both produce excellent action. Ephemerella dorothea dorothea is a small species of Sulphur in the East, and Ephemerella dorothea infrequens (formerly Ephemerella infrequens) is one of the two main Pale Morning Dun hatches of the West.
View 6 PicturesI keyed this nymph carefully under a microscope to check that it's Ephemerella dorothea.
View 6 Pictures
View 5 Pictures
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