**Mayfly Species Drunella spinifera (Western Slate Olive Dun)**

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Ephemeroptera (Mayflies)

» Family Ephemerellidae (Hendricksons, Sulphurs, PMDs, BWOs)

» Genus Drunella (Blue-Winged Olives)

» Species spinifera (Western Slate Olive Dun)

Common Names

Match	Common Name
	Western Slate Olive Dun
	Small Western Green Drake

Pictures Below ↓

This taxon prefers cold water and does not flourish where water temperatures exceed 60 degrees. As with the slightly larger Drunella coloradensis, this species prefers cold tailwaters, high elevation headwaters and spring creeks.

Where & When

Region: West

Time Of Year (?): August and September

This species is most prevalent near the Pacific Coast, but scattered local populations occur throughout the northern states of the West.

Spinner Behavior

Time Of Day: Dusk

These spinner flights are too sparse to be important.

Pictures of 4 Western Slate Olive Dun Specimens:

Specimen Page:12

Male Drunella spinifera (Western Slate Olive Dun) Western Slate Olive Dun Nymph

Male Drunella spinifera (Western Slate Olive Dun) Mayfly Nymph

View 8 PicturesIn a bucket full of Drunella coloradensis nymphs, this was the only specimen of Drunella spinifera (and the first one I've found anywhere).

Collected July 28, 2019 from Mystery Creek #199 in Washington
Added to Troutnut.com by Troutnut on July 30, 2019

Drunella spinifera (Western Slate Olive Dun) Western Slate Olive Dun Nymph

Drunella spinifera (Western Slate Olive Dun) Mayfly Nymph

View 3 PicturesThis species resembles Drunella grandis but the spines tell the story.

Collected December 19, 2009 from 6 mile Creek in Montana
Added to Troutnut.com by Bnewell on June 26, 2011

Female Drunella spinifera (Western Slate Olive Dun) Western Slate Olive Dun Dun

Female Drunella spinifera (Western Slate Olive Dun) Mayfly Dun

View 2 Pictures

Collected July 9, 2007 from Fern Creek in Montana
Added to Troutnut.com by Bnewell on June 29, 2011

Specimen Page:12

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Jargon Defined:

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.

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