Iron Blue Duns

Mayflies

Caddisflies

Stoneflies

Scientific Names

Match	Scientific Name
	Paraleptophlebia adoptiva
	Leptophlebia cupida
	Leptophlebia johnsoni
	Paraleptophlebia mollis

Like most common names, "Iron Blue Dun" can refer to more than one taxon. They're previewed below, along with 5 specimens. For more detail click through to the scientific names.

Mayfly Species Paraleptophlebia adoptiva

These are very rarely called Iron Blue Duns.

This is the best Spring hatch after the Quill Gordons (Epeorus pleuralis) but before the Hendricksons (Ephemerella subvaria) in most parts of the East, although it can overlap with both. The Blue Quills are small mayflies (hook size 16-20) but they can hatch in incredible numbers at a time when eager trout are just beginning to look to the surface after a hungry winter.

Male Paraleptophlebia adoptiva (Blue Quill) Mayfly Dun

View 14 Pictures

Collected April 30, 2007 from in
Added to Troutnut.com by on May 3, 2007

Mayfly Species Leptophlebia cupida

These are very rarely called Iron Blue Duns.

Most anglers encounter these large mayflies every Spring in the East and Midwest. They are omnipresent in small portions, providing filler action in the days or hours between the prolific hatches of the early season Ephemerella flies.

See the main Leptophlebia page for details about their nymphs, hatching, and egg-laying behavior. This is by far the most important species of that genus.

Leptophlebia cupida (Black Quill) Mayfly Nymph

View 8 Pictures

Collected March 29, 2005 from in
Added to Troutnut.com by on April 6, 2006

Male Leptophlebia cupida (Black Quill) Mayfly Dun

View 6 PicturesThis Leptophlebia cupida dun was extremely cooperative, and it molted into a spinner for me in front of the camera. Here I have a few dun pictures and one spinner picture, and I've put the entire molting sequence in an article.

Collected May 27, 2005 from in
Added to Troutnut.com by on May 16, 2006

Female Leptophlebia cupida (Black Quill) Mayfly Spinner

View 7 Pictures

Collected May 28, 2005 from in
Added to Troutnut.com by on May 24, 2006

See 14 more specimens...

Mayfly Species Leptophlebia johnsoni

These are very rarely called Iron Blue Duns.

Mayfly Species Paraleptophlebia mollis

These are very rarely called Iron Blue Duns.

This species often emerges together with Paraleptophlebia strigula and Paraleptophlebia guttata, and the combined effect can be a good fishable hatch. The latter two are much less famous than mollis, but Knopp and Cormier say they are more reliable.

Male Paraleptophlebia mollis (Jenny Spinner) Mayfly Dun

View 6 Pictures

Collected June 8, 2005 from in
Added to Troutnut.com by on May 26, 2006

Jargon Defined:

Dun: 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.

Molting: When aquatic insects with hard exoskeletons (like mayfly and stonefly nymphs) grow bigger, their exoskeleton does not grow with them. Instead they grow a new, larger one underneath and shed the old one when it's too small. This process is called molting.

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).

Spinner: There are two winged stages of adult mayflies. They emerge from the water as duns, molt on land (usually) into their fully mature stage, spinners. As spinners, they mate, lay eggs, and die.

Useful References:

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