Troutnut.com Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

Little Blue-Winged Olives

Scientific Names
MatchScientific Name
****Diphetor hageni
***Labiobaetis
***Attenella delantala
***Labiobaetis propinquus
***Attenella soquele
**Baetis
*Attenella margarita

Like most common names, "Little Blue-Winged Olive" 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 Diphetor hageni

These are pretty much always called Little Blue-Winged Olives.
This is one of the most important species of the Baetidae family. Previously known as Baetis parvus in the West and its synonym (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) Baetis devinctus in the East, it is distributed across the country but most of its fame comes from excellent hatches in the West. Prior to all the species being combined with Baetis tricaudatus, most angling literature considered it the most populous and widespread western species of the Baetidae family.

Dorsal (Dorsal: Top.) abdominal markings on the nymphs used to differentiate the species in these older works have since proved unreliable. The easiest way to tell them apart from B. tricaudatus is their lack of gills on the first abdominal segment. Telling adults apart is equally tough. Duns of D. hageni are typically a little smaller, but their bodies can also be olive, brownish olive and even two toned with thoraxes a shade of brown or tan with paler olivacious abdomens.

Diphetor hageni has two former names used in angling literature, Baetis parvus in the West and Baetis divinctus in the East.

Mayfly Genus Labiobaetis

These are often called Little Blue-Winged Olives.
This genus contains only one species of interest to anglers, Labiobaetis propinquus. See the species hatch page for more information.

The species of this genus can be identified by the combination of its tiny elliptical hindwings lacking costal projections (
The costal projection of a Baetidae dun.
The costal projection of a Baetidae dun.
Costal projection: A bump or point sticking up from the front margin of an insect's wing, usually the rear wing of certain mayflies. It is sometimes called a costal process.
)
( a few obscure species have them but they are so reduced as to be barely observable under low magnification) and lacking a conical mesonotal projection (Conical mesonotal projection: small cone shaped spike sticking up from the top and front part of the middle thorax segment.). Their two tailed nymphs are more difficult.

Mayfly Species Attenella delantala

These are often called Little Blue-Winged Olives.

Mayfly Species Labiobaetis propinquus

These are often called Little Blue-Winged Olives.
This species was previously known as Baetis propinquus, a name from older nomenclatures and angling literature familiar to many western anglers. Prior to its current listing, it did a brief stint in the genus Pseudocloeon. The irony is that though this species has hind wings, it was the last species remaining in Pseudocloeon (before the genus recent Nearctic taxonomic demise) which was best known for its species lacking hind wings as an identifying character.

Though it has a national distribution its most important hatches occur in the West, usually hatching between the larger broods of Baetis tricaudatus. Western anglers experiencing a hatch can easily confuse them with the larger Baetis bicaudatus as both nymphs appear similar with only two tails. Besides size, the adults can be separated from bicaudatus (with the help of a little magnification) because L. propinquus lacks acute costal projections (
The costal projection of a Baetidae dun.
The costal projection of a Baetidae dun.
Costal projection: A bump or point sticking up from the front margin of an insect's wing, usually the rear wing of certain mayflies. It is sometimes called a costal process.
)
on its tiny hind wings. Conversely, the presence of hind wings and lack of conical mesonotal projections (Conical mesonotal projection: small cone shaped spike sticking up from the top and front part of the middle thorax segment.) makes them easy to tell from the more common and equally tiny Acentrella turbida.

Mayfly Species Attenella soquele

These are often called Little Blue-Winged Olives.

Mayfly Genus Baetis

These are sometimes called Little Blue-Winged Olives.
This is one of the most prolific genera of mayflies in North American trout streams. Their small size permits the growth of up to three generations per year, and they are good dry-fly insects because they often hatch in impressive numbers and the duns ride the water for a long time before taking flight.

The genus Baetis and its species are probably the most misidentified mayflies in angling. Many who see mayflies too small to imitate with a size 16 Adams call them Baetis, especially if they're olive in coloration. In reality, Baetis (though the most prominent) is only one of several very similar and abundant genera in the family Baetidae. It seems species in the family are perpetually being reclassified, and identifying any of them, even to genus level is difficult. The angler who wants to describe what is seen streamside usually has only four choices:

1. Call them "Blue-Winged Olives" as most do. the problem is this name has lost all meaning due to being applied to dozens of species across several families (many of which have neither blue wings nor olive bodies). Besides, the name was originally coined for a species of British ephemerellid, the family where this common name should properly reside.

2. Call them "baetids", the Latin name for referring to members of the Baetidae family as a group. While technically accurate scientifically, it doesn't tell the listener or reader much about their appearance.

3. Call them outmoded scientific names - Even calling them by the updated name is usually risky for most species in the field. Adding to the difficulty by using names from outdated nomenclatures? Talk about confusion...

4. Call them "little (whatever color they are) quills." Perhaps this is the best choice as at least it's more accurately descriptive.

The fact is many are so similar that even alot of the specimens in the hatch pages can't be keyed below the family level with absolute certainty; at least from what's observable in the photos alone. They often require observation with a microscope and extensive knowledge of the subtle differences for accurate determinations. So - the next time a fishing buddy identifies a little olive mayfly from a distance using an obsolete name like Baetis vagans, just smile and nod...

For anglers raised on Schwiebert, Swisher, etc., it is often difficult to locate many important species in the newer literature. When working with older taxonomies and/or angling texts, the following hatch page links may prove helpful:

Baetis devinctus = Diphetor hageni (can be an important eastern species)
Baetis hiemalis = Baetis brunneicolor (important Midwest species with a national distribution)
Baetis insignificans = Acentrella insignificans (can be important in some western locales)
Baetis parvus = Diphetor hageni (very important western species)
Baetis propinquus = Labiobaetis propinquus (important in the West with a national distribution)
Baetis pygmaeus = Acerpenna pygmaea (can be important with distribution across all regions)
Baetis vagans = Baetis tricaudatus (most abundant and important species nationwide)

The relatively new genus Fallceon has two species of interest that are made up of several previous Baetis species. They are distributed nationally and may prove significant as more is learned about the angling opportunities they present, especially in the the South and Southwest.
Baetis (Blue-Winged Olives) Mayfly NymphBaetis (Blue-Winged Olives) Mayfly Nymph View 10 Pictures
Collected May 6, 2007 from in
Added to Troutnut.com by on May 18, 2007
Male Baetis (Blue-Winged Olives) Mayfly DunMale Baetis (Blue-Winged Olives) Mayfly Dun View 14 PicturesThis dun molted most of the way into a spinner (though the wings got stuck) the evening after I photographed it, so I took some more photos of the spinner.

I found a female nearby, probably of the same species.
Collected September 19, 2006 from in
Added to Troutnut.com by on October 4, 2006
Female Baetis (Blue-Winged Olives) Mayfly SpinnerFemale Baetis (Blue-Winged Olives) Mayfly Spinner View 4 PicturesI captured and photographed this specimen as a dun before she molted into the spinner photographed here. Her wings got a bit torn up in the process.
Collected April 19, 2006 from in
Added to Troutnut.com by on April 21, 2006
Male Baetis tricaudatus (Blue-Winged Olive) Mayfly AdultMale Baetis tricaudatus (Blue-Winged Olive) Mayfly Adult View 2 Pictures
Collected May 16, 2012 from in
Added to Troutnut.com by on May 18, 2012

Mayfly Species Attenella margarita

These are very rarely called Little Blue-Winged Olives.
Though having a national distribution, this species is considered by angling authorities to be important only in the West. In localized waters where it is abundant, it can be a significant hatch.
Female Attenella margarita (Little Western Blue-Winged Olive) Mayfly DunFemale 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 in
Added to Troutnut.com by on October 3, 2006
Top 10 Fly Hatches
Top Gift Shop Designs
Top Insect Specimens
Miscellaneous Sites