**Mayfly Species Siphlonurus alternatus (Gray Drake)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Siphlonuridae (Gray Drakes)

» Genus Siphlonurus (Gray Drakes)

» Species alternatus (Gray Drake)

Common Names

Match	Common Name
	Gray Drake
	Adams
	Brown Quill Spinner
	Black Drake

Pictures Below ↓

This species occasionally produces important spinner falls. Its spinners may join the swarms of Siphlonurus quebecensis or Siphlonurus rapidus, amplifying the importance of all three species.

Where & When

Regions: East, Midwest

Time Of Year (?): Early May through early September; peaking from late June through July

Spinner Behavior

Time Of Day: Evening

Habitat: Riffles

Pictures of 2 Mayfly Specimens in the Species Siphlonurus alternatus:

Siphlonurus alternatus (Gray Drake) Mayfly Nymph

View 2 Pictures

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

Female Siphlonurus alternatus (Gray Drake) Mayfly Spinner

View 7 PicturesI'm tentatively classifying this one as Siphlonurus alternatus, because it seems to fit that species best in the old keys in Needham's Biology of Mayflies, but I'm hesitant because I can't find documentation that southwest Montana or the surrounding area is within the species' range, although they are widely distributed throughout eastern North American and western Canada.

Collected July 2, 2019 from the Gallatin River in Montana
Added to Troutnut.com by Troutnut on July 18, 2019

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Jargon Defined:

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.

Leonard, Justin W. and Fannie A. Leonard. 1962. Mayflies of Michigan Trout Streams. Cranbrook Institute of Science.

Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.