Mayfly Genus Attenella

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)

» Genus Attenella

Species in Attenella
Attenella attenuataSmall Eastern Blue-Winged Olive	0	0
Attenella delantalaSmall Blue-Winged Olive	0	0
Attenella margaritaLittle Western Blue-Winged Olive	0	0

1 species isn't included.

Pictures Below ↓

This genus is represented by several important species across the country. In the East, Attenella attenuata (Little Blue-winged Olive) has garnered much attention as an important hatch in past angling texts. However, possible confusion with more abundant Drunella species of Blue-winged Olives has perhaps led to overstatement regarding its importance.

The species Attenella margarita (Little Western Blue-winged Olive) is disributed nationally. Though its eastern presence is relatively minor, in the West this mayfly can produce exceptional hatches.

Two other western species, Attenella delantala and to a lesser extent Attenella soquele often show up quite prominently in stream samples taken in the coastal states. The dramatically marked delantala nymph cannot be easily confused with any other western ephemerellid. Information regarding their winged appearance seems to be unavailable for now. Why they have gone unreported in angling texts is a mystery perhaps due to emergence behavior or misidentification by anglers of the dun and spinner stages. There is much to learn about these species that can be fairly abundant in some locales.

Hatching Behavior

A significant difference between this genus and other ephemerellids is it's reported propensity to emerge from its nymphal shuck (

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Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.

Shuck: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.) from the stream bottom in heptagenid fashion. While other ephemerellids can and do emerge underwater, this usually takes place within a foot at most from the surface. Attenella's availability as a submerged dun in the entire water column means use of the winged wetfly or soft hackles fished deeply can be an important tactic.

Pictures of 7 Mayfly Specimens in the Genus Attenella:

Specimen Page:12

Female Attenella margarita (Little Western Blue-Winged Olive) Mayfly Dun

View 6 PicturesI found this dun unusually late in the year for anything in the Ephemerellidae family in the East. It's also small for that family.

Collected September 4, 2006 from Willowemoc Creek in New York
Added to Troutnut.com by Troutnut on October 3, 2006

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 the Namekagon River in Wisconsin
Added to Troutnut.com by Troutnut on May 26, 2006

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

View 3 PicturesThis specimen came from the same hatch as a female.

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

Specimen Page:12

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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.

Emergence: The transformation of a nymph or pupa into the adult winged stage of an insect. The term may refer to the emergence of an individual, or the daily or yearly event in which all individuals of a species emerge.

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).

View Full Size

Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.

Shuck: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.

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.