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.

Here Oksrukuyik Creek flows away from the Dalton Highway toward the pipeline. It eventually grows into one of the major rivers of the North Slope, and the main drainage to the west of the Sag, but where it crosses the road it's just a small grayling stream.

From Oksrukuyik Creek in Alaska

Stream photos

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Holocentropus Caddisfly Larva Holocentropus Caddisfly Larva

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.

11 Recently Added Photos

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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Male Penelomax septentrionalis Mayfly Nymph Pictures

This is surely the most distinctive-looking species in Ephemerellidae. I like the rugged, spindly look. If mayflies made movies, Penelomax septentrionalis would probably play the supervillain.

Maybe I should take a break and get something to eat.

Ruler view of a Male Penelomax septentrionalis (Ephemerellidae) Mayfly Nymph from the Delaware River in New York The smallest ruler marks are 1 mm.

Dorsal view of a Male Penelomax septentrionalis (Ephemerellidae) Mayfly Nymph from the Delaware River in New York

Male Penelomax septentrionalis (Ephemerellidae) Mayfly Nymph from the Delaware River in New York

Ventral view of a Male Penelomax septentrionalis (Ephemerellidae) Mayfly Nymph from the Delaware River in New York

A hairy mayfly nymph. This gangly, odd-looking nymph is from the rare species Ephemerella septentrionalis

Artistic view of a Male Penelomax septentrionalis (Ephemerellidae) Mayfly Nymph from the Delaware River in New York

This mayfly was collected from the Delaware River in New York on May 13th, 2007 and added to Troutnut.com by Troutnut on May 18th, 2007.

Discussions of this Nymph

Great Photos

2 replies

Posted by Earlfishman on May 19, 2007

Last reply on May 19, 2007 by Troutnut

Jason,

The underwater photos are unreal. What sort of lens are you using on that camera? It is just now occuring to me to ask how many of your pictures on this site are taken through a scope and how many are taken with just a camera?

Earl

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