**Mayfly Species Baetis brunneicolor (Blue-Winged Rusty Dun)**

Mayflies

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Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Baetidae (Blue-Winged Olives)

» Genus Baetis (Blue-Winged Olives)

» Species brunneicolor (Blue-Winged Rusty Dun)

Common Names

Match	Common Name
	Blue-Winged Rusty Dun
	BWO
	Little Blue-Winged Olive
	Rusty Spinner
	Slate-Winged Brown Quill
	Little Slate-Winged Brown Quill

This is the largest common species of Baetis on our trout streams, and it can hatch in incredible numbers, drawing impressive rises of selective trout.

Anglers may have read in books about Baetis hiemalis, which is now a synonym (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) of Baetis brunneicolor. It appears to have been a name for the fall-hatching brood of this species, which was reported to prefer slow water and weedy habitat instead of the gravelly riffles of the early summer brood.

Where & When

Regions: East, Midwest, West

Time Of Year (?): June through mid-November; best in early summer and again in the fall

Baetis brunneicolor is most often praised for the action it creates in the Midwest, but it is locally abundant in parts of the East and maybe in the West as well.

Hatching Behavior

Time Of Day (?): Sometimes all day long; best in late afternoon to evening

The duns drift a long distance on the water before taking flight, making them excellent dry-fly insects.

Nymph Biology

Current Speed: Any

Substrate: Gravel, vegetation

Recent Discussions of Baetis brunneicolor

Big Green River, Wisconsin, late September 1 Reply »

Posted by Admiralb on Sep 28, 2013

Last reply on Sep 30, 2013 by Entoman

I hosted two visiting delegates to the T.U. National Convention in Madison, WI. on September 25, 2013, taking them to the Big Green River in Grant County near Fennimore. There was a high overcast in the morning, and these mayflies [which I merely called "BWO's" and imitated with #16 parachute dries - thin olive bodies, gray wing posts and dun parachute hackle] - were active. Both of my guests raised browns fishing a gray nymph behind a #16 parachute dry BWO. As long as my flies catch fish, I don't need to be a detailed entomologist. Nevertheless, I do sincerely appreciate the detailed scientific info, because it helps me focus my flytying and fly selection. Thank you.

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Jargon Defined:

Brood: When a species produces more than one generation per year, each one is called a brood.

Duns: 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.

Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.

Useful References:

Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.

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

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

Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.