Blue-winged Olives
Baetis
Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
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Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
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Gray Foxes
Like most common names,"Gray Fox" can refer to more than one taxon. They're previewed below, along with 13 specimens. For more detail click through to the scientific names.
Mayfly Species Stenonema vicarium
These are often called Gray Foxes.
In the East and Midwest this is one of the most important hatches of the Spring. They are large flies which emerge sporadically, making for long days of good fishing.
This species contains the two classic Eastern hatches formerly known as Stenonema vicarium and Stenonema fuscum, the "March Brown" and "Gray Fox." Entomologists have discovered that these mayflies belong to the same species, but they still display differences in appearance which the trout notice easily. Anglers should be prepared to imitate both types.
This species contains the two classic Eastern hatches formerly known as Stenonema vicarium and Stenonema fuscum, the "March Brown" and "Gray Fox." Entomologists have discovered that these mayflies belong to the same species, but they still display differences in appearance which the trout notice easily. Anglers should be prepared to imitate both types.
I collected this mayfly on the same trip as a female of the same species. After these photos it molted into a spinner. This is the form of Stenonema vicarium which anglers call the "Gray Fox."
See 17 more specimens...
Mayfly Species Heptagenia solitaria
These are sometimes called Gray Foxes.
This species is common in the Flathead River below Kerr Day. The river here is fairly warm with a cobble and boulder bottom with heavy periphyton at times. This species is not common elsewhere in western Montana.
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Mayfly Genus Stenacron
These are very rarely called Gray Foxes.
The species in this genus were formerly classified in Stenonema. See the genus Maccaffertium for details. Only one species, Stenacron interpunctatum, is important to fly fishermen. See its page for details.
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Mayfly Species Stenacron interpunctatum
These are very rarely called Gray Foxes.
This is the best of the sporadic summer hatches known to anglers as Light Cahills. It was formerly known as Stenonema canadense and is considered by most angling historians as the model for that classic Catskill pattern.
This is a fairly small late-season female Stenacron dun.
Mayfly Species Ephemera varia
These are very rarely called Gray Foxes.
This is an excellent hatch of a different character than its Ephemera brethren. Rather than emerging in a flurry of activity within a week, the Ephemera varia hatch may last for more than a month in a single place.
This yellow drake dun hatched out of my aquarium over a month before her brethren in the wild are slated to emerge. She seems a bit small, and that might be the reason.
I found this female spinner ovipositing in a small stream. She came along while I was playing a trout -- every good bug seemed to do that last night! I didn't have my bug net, so I caught the trout in my landing net, released the trout, and caught the mayfly in my landing net. Her wing got a bit messed up from that.
References
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.