Slate-Winged Mahogany Duns

There are many species in this genus of mayflies, and some of them produce excellent hatches. Commonly known as Blue Quills or Mahogany Duns, they include some of the first mayflies to hatch in the Spring and some of the last to finish in the Fall.

In the East and Midwest, their small size (16 to 20, but mostly 18's) makes them difficult to match with old techniques. In the 1950s Ernest Schwiebert wrote in Matching the Hatch:


Fortunately, modern anglers with experience fishing hatches of tiny Baetis and Tricorythodes mayflies (and access to space-age tippet materials) are better prepared for eastern Paraleptophlebia. It's hard to make sense of so many species, but only one is very important and others can be considered in groups because they often hatch together:

• Paraleptophlebia adoptiva is by far the most important species of this genus in the two regions and is an early Spring emerger.


• Paraleptophlebia mollis, Paraleptophlebia guttata, and Paraleptophlebia strigula complement each other in late spring and early summer.


• Paraleptophlebia debilis and Paraleptophlebia praepedita occur together in the fall.

In the West, it is a different story. For starters the species run much larger and can be imitated with flies as large as size 12, often size 14, and rarely smaller than 16. Another difference is the West has species with tusks! Many anglers upon first seeing them think they are immature burrowing nymphs of the species Ephemera simulans aka Brown Drake. With their large tusks, feathery gills, and slender uniform build, it's an easy mistake to make. Using groups again:

• The most important species is Paraleptophlebia debilis. This large (for the genus) Fall emerger can be found throughout the region. It is often accompanied by one of the slightly larger tusked species. Depending on locale, this can be Paraleptophlebia bicornuta (the most common), Paraleptophlebia packii or Paraleptophlebia helena. Check out their hatch pages for distribution information.


• Spring is the season for the smaller Paraleptophlebia heteronea throughout most of the region with Paraleptophlebia gregalis filling this niche in California and parts of Oregon.

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