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**Mayfly Genus Eurylophella (Chocolate Duns)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

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

» Genus Eurylophella (Chocolate Duns)

Species in Eurylophella
Eurylophella bicolorChocolate Dun	0	0
Eurylophella funeralisChocolate Dun	0	0
Eurylophella lutulentaChocolate Dun	0	0
Eurylophella temporalisChocolate Dun	0	0

10 species aren't included.

Common Name

Match	Common Name
	Chocolate Duns

Pictures Below ↓

None of the species in this genus are recognized as significant hatches. Nevertheless, I have found their nymphs in my samples in many streams in both the East and Midwest.

Where & When

Regions: East, Midwest

Time Of Year (?): May and June

This genus is widespread throughout the East and Midwest but rarely abundant. The few species for which emergence dates are available all emerge in May and June.

Nymph Biology

Current Speed: Slow

These nymphs probably inhabit slow water where the bottom is covered with silt or detritus (Detritus: Small, loose pieces of decaying organic matter underwater.). The 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 they possess are a common adaptation evolved by mayflies in such environments.

Pictures of 22 Mayfly Specimens in the Genus Eurylophella:

Specimen Page:12 3

Male Eurylophella (Chocolate Duns) Mayfly Spinner

View 10 Pictures

Collected June 4, 2005 from the Teal River in Wisconsin
Added to Troutnut.com by Troutnut on May 24, 2006

Eurylophella temporalis (Chocolate Dun) Mayfly Nymph

View 9 Pictures

Collected June 5, 2005 from the Marengo River in Wisconsin
Added to Troutnut.com by Troutnut on May 25, 2006

Eurylophella (Chocolate Duns) Mayfly Nymph

View 5 PicturesThis nymph is an extremely early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.).

Collected February 7, 2004 from unknown in Wisconsin
Added to Troutnut.com by Troutnut on January 25, 2006

Specimen Page:12 3

Recent Discussions of Eurylophella

florida mayfly nymph imitations 2 Replies »

Posted by Homer47 on Sep 5, 2012 in the species Eurylophella temporalis

Last reply on Sep 6, 2012 by Sayfu

Looks like an imitation would be about a #10 or #8 dark brown nymph pattern. I'm down here in north Fla and trying to match the hatch in the far north central part of the state, mostly to fool the bream. Any ideas or help would be appreciated. I found two patterns so far that seem to work- a little brown nymph with a rusty brown/orange thorax(maybe this is a good representation of the E. Temporalis), and a size 12 buzzer nymph with black body, peacock thorax and white breathing filament. The bream seemed to agree with that choice. I would like to try and copy more local insects as I figure out what they are.There are dragonflies and damselflies and mosquitoes. I could start there.

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Jargon Defined:

Detritus: Small, loose pieces of decaying organic matter underwater.

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.

Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.

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.

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.