**Mayfly Species Rhithrogena hageni (Western Black Quill)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Heptageniidae (March Browns, Cahills, Quill Gordons)

» Genus Rhithrogena

» Species hageni (Western Black Quill)

Common Names

Match	Common Name
	Western Black Quill
	Western March Brown
	Dark Tan Spinner
	Pale Brown Dun
	Black Quill

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 58°F, the spinner fall is often delayed until the next morning.

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Jargon Defined:

Duns: 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.

Nymphs: 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.

Useful References:

Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.

Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.

Knopp, Malcolm and Robert Cormier. 1997. Mayflies: An Angler's Study of Trout Water Ephemeroptera . The Lyons Press.