**Mayfly Species Drunella coloradensis (Small Western Green Drake)**

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 coloradensis (Small Western Green Drake)

Common Names

Match	Common Name
	Small Western Green Drake
	Slate-Winged Olive
	Western Green Drake
	Dark Olive Dun
	Dark Brown Spinner
	Autumn Green Drake

Pictures Below ↓

This species is very similar to Drunella flavilinea. In areas where their ranges overlap, they can sometimes be found in the same streams. Allen and Edmunds (1962) say that Drunella coloradensis tends to favor colder water than Drunella flavilinea and that it may emerge as much as a month later.

Where & When

Region: West

Time Of Year (?): July to early October

Preferred Waters: Small streams

Altitude: High

According to Fred Arbona, this species requires streams which never exceed 60°F, and this limits them to small streams at high altitude.

Pictures of 10 Mayfly Specimens in the Species Drunella coloradensis:

Specimen Page:12

Drunella coloradensis (Small Western Green Drake) Mayfly Nymph

View 11 PicturesThis one nicely illustrates the variation in coloration within an single Ephemerellid species in a single stream, when compared to its lighter, banded counterpart.

Collected July 25, 2019 from Mystery Creek #249 in Washington
Added to Troutnut.com by Troutnut on July 26, 2019

Male Drunella coloradensis (Small Western Green Drake) Mayfly Dun

View 8 PicturesThe positive species ID on this dun comes from both the spinner that it (or possibly one other dun just like it) molted into and the overwhelming abundance of nymphs of this species in my kicknet samples from the same site.

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

Drunella coloradensis (Small Western Green Drake) Mayfly Nymph

View 5 Pictures

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

Specimen Page:12

Your Thoughts On Drunella coloradensis:

You must log in at the top of the page to post. If you haven't registered yet, it's this easy:

Jargon Defined:

Dun: 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.

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.