**Mayfly Species Baetisca obesa (Armored Mayfly)**

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Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Baetiscidae (Armored Mayflies)

» Genus Baetisca (Armored Mayflies)

» Species obesa (Armored Mayfly)

Common Names

Match	Common Name
	Armored Mayfly
	Batfly
	Humpbacked Nymph
	Speckled-Winged Dun
	No-Name Mayfly

Pictures Below ↓

I have no experience with important fishing to this species, but it is probably the Baetisca species that Ernest Schwiebert discussed in Nymphs as locally abundant on one stretch of a Catskill river.

See the Baetisca genus page for more details.

Where & When

Regions: East, Midwest

This is the most common species of Baetisca in the East. Its official range extends into the Midwest, but populations there are overshadowed by the more prolific Baetisca laurentina.

Pictures of 3 Mayfly Specimens in the Species Baetisca obesa:

Baetisca obesa (Armored Mayfly) Mayfly Nymph

View 12 Pictures

Collected May 6, 2007 from the Neversink River (above reservoir) in New York
Added to Troutnut.com by Troutnut on May 10, 2007

Baetisca obesa (Armored Mayfly) Mayfly Nymph

View 10 Pictures

Collected May 6, 2007 from the Neversink River (above reservoir) in New York
Added to Troutnut.com by Troutnut on May 10, 2007

Female Baetisca obesa (Armored Mayfly) Mayfly Dun

View 12 PicturesThis Baetisca obesa dun hatched out in my aquarium from nymphs collected a couple weeks earlier.

Collected May 23, 2007 from the Neversink River (aquarium-raised) in New York
Added to Troutnut.com by Troutnut on June 4, 2007

Recent Discussions of Baetisca obesa

Similiar found in Minnesota 1 Reply »

Posted by PRohlfsen on May 11, 2007

Last reply on May 11, 2007 by Troutnut

I was fishing the Vermillion River in Minnesota south of the metro area and found a nymph similar to the Armored Mayfly Nymph. It did appear to be much more green in color. It was moving through a really muddy part of the stream, which I found interesting.

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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).

Useful References:

Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.

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

Leonard, Justin W. and Fannie A. Leonard. 1962. Mayflies of Michigan Trout Streams. Cranbrook Institute of Science.

Schwiebert, Ernest. 1973. Nymphs. Wichester Press.