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Mayfly Species Rhithrogena hageni (Western Black Quill)

Pictures Below
According to Fred Arbona in Mayflies, the Angler, and the Trout, this is an excellent hatch and one of the most common fast-water mayflies in the West.  

Where & When


Region: West

Time Of Year (?): July to August

Preferred Waters: Large rivers and streams

Altitude: Above 5,000 feet
There are conflicting accounts of the hatch dates for this species. Caucci and Nastasi list it as a July-August emerger, but Knopp and Cormier speak of it hatching in the spring.

Hatching Behavior


Time Of Day (?): Late morning on warm days; early afternoon on cold days

The nymphs emerge on the bottom of the river and float to the surface as fully formed duns.

Spinner Behavior


Time Of Day: Late evening to dusk

The spinner falls are more important than the emergence. Knopp and Cormier give an unusually specific description of the conditions for a spinner fall in Mayflies: An Angler's Study of Trout Water Ephemeroptera :

Female spinners commence their fall during the evening or just before dusk, when air temperature has fallen to the low 60s F. If the air temperature drops below 58F, the spinner fall is often delayed until the next morning.

Pictures of 3 Mayfly Specimens in the Species Rhithrogena hageni:

Male Rhithrogena hageni (Western Black Quill) Mayfly SpinnerMale Rhithrogena hageni (Western Black Quill) Mayfly Spinner View 10 PicturesI collected this spinner from the trail (old logging road) above a whitewater canyon on a small stream in the Cascades. I'm using its positive ID to put a species ID on a female dun and [speclink id]1217]mature nymph collected on the same trip.
Collected July 4, 2020 from Mystery Creek #249 in Washington
Added to Troutnut.com by Troutnut on July 12, 2020
Female Rhithrogena hageni (Western Black Quill) Mayfly DunFemale Rhithrogena hageni (Western Black Quill) Mayfly Dun View 7 PicturesI was surprised by the olive cast on the body of this female Rhithrogena dun, which led me to mistake it for a western green drake (Drunella) in the field. I was pleasantly surprised to get a closer look and find something I hadn't collected yet. Its species ID is based on proximity to male spinner collected on the same trip, as well as physical similarity (size, tergite (
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.
)
coloration, dark streaks on the femora (
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.
)
) to that specimen.
Collected July 4, 2020 from Mystery Creek #249 in Washington
Added to Troutnut.com by Troutnut on July 12, 2020
Rhithrogena hageni (Western Black Quill) Mayfly NymphRhithrogena hageni (Western Black Quill) Mayfly Nymph View 9 PicturesI'm basing the ID of this near-mature nymph on a male spinner with similar size and markings, collected on the same trip. There isn't a key to reliably identify the nymphs of most Rhithrogena species otherwise.
Collected July 4, 2020 from Mystery Creek #249 in Washington
Added to Troutnut.com by Troutnut on July 12, 2020

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