Dun Variants

Mayflies

Caddisflies

Stoneflies

Scientific Names

Match	Scientific Name
	Isonychia bicolor
	Attenella attenuata

Like most common names, "Dun Variant" 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 Isonychia bicolor

These are often called Dun Variants.

This is by far the most important species of Isonychia. Many angling books once split its credit with the species Isonychia sadleri and Isonychia harperi, but entomologists have since discovered that those are just variations of this abundant species.

See the main Isonychia page for more about these intriguing mayflies.

Isonychia bicolor (Mahogany Dun) Mayfly Nymph

View 7 PicturesThis Isonychia bicolor nymph from the Catskills displays the prominent white stripe sometimes characteristic of its species. This is the first such specimen I've photographed, because members of the same species in the Upper Midwest have a more subdued stripe (and were once thought to be a different species, Isonychia sadleri). The striking coloration on this eastern nymph is more appealing.

Collected April 19, 2006 from in
Added to Troutnut.com by on April 21, 2006

Female Isonychia bicolor (Mahogany Dun) Mayfly Dun

View 13 Pictures

Collected June 14, 2005 from in
Added to Troutnut.com by on May 26, 2006

Male Isonychia bicolor (Mahogany Dun) Mayfly Spinner

View 15 PicturesI got several really nice pictures of this spinner. I also collected a female on the same trip.

Collected August 9, 2006 from in
Added to Troutnut.com by on August 11, 2006

See 16 more specimens...

Mayfly Species Attenella attenuata

These are very rarely called Dun Variants.

This intriguing species has received a lot of attention in past angling books. Recent authors suspect that much of this credit was a case of mistaken identity, with Attenella attenuata receiving praise for the hatches of Drunella lata and Dannella simplex. Much of the credit was legitimate and accurate, but this species is no longer thought to be on par with its most popular cousins in Ephemerella and Drunella.

I have several specimens listed under this species, but I'm not positive the identification is correct.

Female Attenella attenuata (Small Eastern Blue-Winged Olive) Mayfly Dun

View 4 PicturesThis specimen came from the same hatch as a male.

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

Female Attenella attenuata (Small Eastern Blue-Winged Olive) Mayfly Spinner

View 11 Pictures

Collected July 1, 2005 from in
Added to Troutnut.com by on April 22, 2006

See 2 more specimens...

Jargon Defined:

Nymph: 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.