**Mayfly Species Paraleptophlebia bicornuta (Mahogany Dun)**

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Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Leptophlebiidae (Blue Quills and Mahogany Duns)

» Genus Paraleptophlebia (Blue Quills and Mahogany Duns)

» Species bicornuta (Mahogany Dun)

Common Names

Match	Common Name
	Mahogany Dun
	Large Slate-Winged Mahogany Dun
	Blue Dun

Pictures Below ↓

This important Western species is one of the few mayflies outside the Ephemeridae family to possess large tusks on the front of its head. It is also one of the largest species of Paraleptophlebia.

P. bicornuta is often reinforced by simultaneous hatches of the more common Paraleptophlebia debilis. The two duns appear virtually identical to the naked eye, though bicornuta usually has an edge in size.

Paraleptophlebia bicornuta is by far the widest distributed tusked species, though there are others. Telling the tusked species apart is very difficult and even entomological texts are largely ambiguous on the characters that differentiate them. Distribution records are probably the most reliable way for anglers to know with any probability what they are looking at. Check out the Paraleptophlebia packii and Paraleptophlebia helena hatch pages for more distribution information.

Where & When

Region: West

Time Of Year (?): September through early November

Hatching Behavior

Time Of Day (?): Morning and afternoon

Pictures of 5 Mayfly Specimens in the Species Paraleptophlebia bicornuta:

Specimen Page:12

Male Paraleptophlebia bicornuta (Mahogany Dun) Mayfly Spinner

View 3 Pictures

Collected September 26, 2011 from the Touchet River in Washington
Added to Troutnut.com by Bnewell on September 26, 2011

Male Paraleptophlebia bicornuta (Mahogany Dun) Mayfly Dun

View 1 PicturesYou wonder sometimes how certain insects get their common names. This one is called the 'mahogany dun' for some unknown reason.

Collected October 5, 2011 from the Touchet River in Washington
Added to Troutnut.com by Bnewell on October 6, 2011

Paraleptophlebia bicornuta (Mahogany Dun) Mayfly Nymph

View 1 PicturesThis species is interesting because it is common in lakes as well as streams. It is one of the last species of the year to emerge in western Montana. Adults have been collected as late as October 15 weather permitting.

Collected July 31, 2007 from Flathead Lake in Montana
Added to Troutnut.com by Bnewell on June 26, 2011

Specimen Page:12

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Jargon Defined:

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.

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.

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