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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Millcreek has attached these 4 pictures to aid in identification. The message is below.
Millcreek
Healdsburg, CA

Posts: 344
Millcreek on Dec 1, 2016December 1st, 2016, 7:12 am EST
This species, Sialis, also known as an alderfly, was identified to genus using Merritt, Cummins And Berg. There is no key to the California species of Sialis larvae.

They are usually found in slackwater areas of rivers and streams with a silt bottom and dead leaves. This one was found in the Russian River and measures about 16mm.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Taxon
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on Dec 2, 2016December 2nd, 2016, 10:05 am EST
Very cool, Mark. I believe larvae are also found in lakes and ponds.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
Millcreek
Healdsburg, CA

Posts: 344
Millcreek on Dec 2, 2016December 2nd, 2016, 1:03 pm EST
Roger-

They are pretty neat little animals. Yeah, they do live in ponds and lakes. And I believe they are also one of the few aquatic insects that pupate on land.
"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein
Taxon
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Site Editor
Plano, TX

Posts: 1311
Taxon on Dec 2, 2016December 2nd, 2016, 3:00 pm EST
Mark-

Right, the Megalopterans and most aquatic Coleopterans.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
Creno
Grants Pass, OR

Posts: 302
Creno on Dec 4, 2016December 4th, 2016, 5:10 am EST
There are also some primarily terrestrial caddis (see Anderson 1967 for a great discussion of Philocasca demita) and a couple where larvae leave the water and pupate terrestrially. There is still alot to be learned about caddis life history in intermittent aquatic systems.
Crepuscular
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Boiling Springs, PA

Posts: 920
Crepuscular on Dec 5, 2016December 5th, 2016, 3:29 am EST
There are also some primarily terrestrial caddis (see Anderson 1967 for a great discussion of Philocasca demita) and a couple where larvae leave the water and pupate terrestrially. There is still alot to be learned about caddis life history in intermittent aquatic systems.


Great stuff here.

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