**Mayfly Species Eurylophella temporalis (Chocolate Dun)**

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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 temporalis (Chocolate Dun)

Common Name

Match	Common Name
	Chocolate Dun

Pictures Below ↓

Where & When

Regions: East, Midwest

Time Of Year (?): Mid-May through early June, perhaps later

Preferred Waters: Lakes and large streams

This widespread Eastern and Midwestern species is not really mentioned in fly fishing literature. The Leonards say in Mayflies of Michigan Trout Streams that it is found in lakes and small streams, though the specimens I collected in northern Wisconsin came from the very small headwaters of a small stream.

Since I have collected the nymphs in early June without the darkened wing pads (

The wing pads on this final instar Baetidae mayfly nymph are extremely dark.

Wing pad: A protrusion from the thorax of an insect nymph which holds the developing wings. Black wing pads usually indicate that the nymph is nearly ready to emerge into an adult.) that would indicate an impending hatch, I assume they emerge later than the dates I've found in books.

Pictures of 1 Mayfly Specimen in the Species Eurylophella temporalis:

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

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Jargon Defined:

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 wing pads on this final instar Baetidae mayfly nymph are extremely dark.

Wing pads: A protrusion from the thorax of an insect nymph which holds the developing wings. Black wing pads usually indicate that the nymph is nearly ready to emerge into an adult.

Useful References:

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