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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington
This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
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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Rhithrogena impersonata (Dark Red Quill) Mayfly Nymph Pictures

This was the only Rhithrogena specimen in a large sample of nymphs from a small Catskill stream. It looks virtually identical to Rhithrogena impersonata specimens collected in the Midwest, but I didn't get to check the distinguishing features under a microscope.

Ruler view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York The smallest ruler marks are 1 mm.
Ventral view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
This picture shows the characteristic gill structure of the Rhithrogena genus more clearly than the mature specimens of Rhithrogena impersonata that I collected back in the Midwest.  The "suction cup" gill structure is an adaptation to help the nymphs cling tight to rocks in fast water.

Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Dorsal view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York

This mayfly was collected from Mongaup Creek in New York on April 19th, 2006 and added to Troutnut.com by Troutnut on April 21st, 2006.

Discussions of this Nymph

identification needed
2 replies
Posted by Kinza on Feb 4, 2017
Last reply on Feb 6, 2017 by Crepuscular
Can you please identify the genus of Family Heptagenedae if I send you images?

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Rhithrogena impersonata (Dark Red Quill) Mayfly Nymph Pictures

Collection details
Location: Mongaup Creek, New York
Date: April 19th, 2006
Added to site: April 21st, 2006
Author: Troutnut
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