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

Mayflies

Caddisflies

Stoneflies

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
	Blue-Winged Olive
	BWO
	Rusty Spinner
	Little Blue-Winged Olive
	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 may occur in the West.

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

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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.