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Western Slate Olive Duns

Like most common names, "Western Slate Olive Dun" can refer to more than one taxon. They're previewed below, along with 5 specimens. For more detail click through to the scientific names.

Mayfly Species Drunella spinifera

These are pretty much always called Western Slate Olive Duns.
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.
Male Drunella spinifera (Western Slate Olive Dun) Western Slate Olive Dun NymphMale 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 in
Added to Troutnut.com by on July 30, 2019

Mayfly Species Drunella flavilinea

These are very rarely called Western Slate Olive Duns.
The Flavs pick up about a week after the closely related but larger Western Green Drakes (Drunella grandis and Drunella doddsii) finish hatching on most Western waters.

Their hatches may be complemented by simultaneous hatches of two less prolific species, Drunella coloradensis and Drunella spinifera.
Drunella flavilinea (Flav) Mayfly NymphDrunella flavilinea (Flav) Mayfly Nymph View 6 PicturesAlthough the identification is not certain because the nymph is not yet mature, the configuration of tubercles (
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled.  They are especially large in this species.
A few (not all) of the abdominal tubercles on this Ephemerella needhami nymph are circled. They are especially large in this species.
Tubercle: Various peculiar little bumps or projections on an insect. Their character is important for the identification of many kinds of insects, such as the nymphs of Ephemerellidae mayflies.
)
on this one--particularly the forefemora--seems to best match Drunella flavilinea.
Collected July 2, 2019 from in
Added to Troutnut.com by on July 18, 2019
Drunella flavilinea (Flav) Mayfly DunDrunella flavilinea (Flav) Mayfly Dun View 1 Pictures
Collected July 31, 2010 from in
Added to Troutnut.com by on June 29, 2011
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