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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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Male Cinygma dimicki (Western Light Cahill) Mayfly Spinner Pictures

A couple days earlier I caught a male spinner of this species with some wing damage and missing tails, so I went back to the same pool try to get one more intact. This one has some leg damage, but between the two specimens you can get an idea what the whole insect looked like. There were small clouds of Cinygma dimicki spinners again over the same two small, specific locations in the pool, which is an interesting testament to how repeatably they choose their ideal mating habitat. I was able to capture this one and a female.

Lateral view of a Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Ruler view of a Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington The smallest ruler marks are 1 mm.
Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Dorsal view of a Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Ventral view of a Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington
Male Cinygma dimicki (Heptageniidae) (Western Light Cahill) Mayfly Spinner from the Cedar River in Washington

This mayfly was collected from the Cedar River in Washington on July 2nd, 2021 and added to Troutnut.com by Troutnut on July 4th, 2021.


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Male Cinygma dimicki (Western Light Cahill) Mayfly Spinner Pictures

Collection details
Location: Cedar River, Washington
Date: July 2nd, 2021
Added to site: July 4th, 2021
Author: Troutnut
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