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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 Sweltsa (Chloroperlidae) (Sallfly) Stonefly Nymph from the Yakima River in Washington
This species was fairly abundant in a February sample of the upper Yakima.
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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Female Drunella tuberculata Mayfly Dun Pictures

I don't know for sure that this is Drunella tuberculata, but that's my best guess for now.

It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.

Markings described for the abdominal sternites of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.

This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.

Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Ventral view of a Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Dorsal view of a Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Lateral view of a Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
The projection under the right eye of this one is interesting.

Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York
Ruler view of a Female Drunella tuberculata (Ephemerellidae) Mayfly Dun from the West Branch of the Delaware River in New York The smallest ruler marks are 1 mm.

This mayfly was collected from the West Branch of the Delaware River in New York on June 7th, 2007 and added to Troutnut.com by Troutnut on June 8th, 2007.

Discussions of this Dun

Insect migration
7 replies
Posted by Mykisslayer on Jan 30, 2014
Last reply on Feb 3, 2014 by PaulRoberts
Do adult aquatic insects travel or migrate to other watersheds or bodies of water? Or do they remain close to the area where they emerged?
Anyone recognize this Drunella?
8 replies
Posted by Troutnut on Jun 8, 2007
Last reply on Sep 21, 2009 by GONZO
I'm a bit puzzled about this one. See the specimen description for details. I know female duns are awful for identification, but this is the only one of its species I could find. Would any of you Ephemerellid experts (Konchu!!) care to take a guess?

Start a Discussion of Dun

Female Drunella tuberculata Mayfly Dun Pictures

Collection details
Location: West Branch of the Delaware River, New York
Date: June 7th, 2007
Added to site: June 8th, 2007
Author: Troutnut
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