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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.
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.

Updates from March 19, 2004

Updates from March 19, 2004

Photos by Troutnut

Several whitetail deer cross the river in front of me in the middle of winter.

Underwater photos by Troutnut

There's a large Ephemerella subvaria nymph in the top left.
Some large Ephemerella mayfly nymphs cling to a log.  In the background, hundreds of Simuliidae black fly larvae swing in large clusters in the current.
Three big Ephemerella subvaria mayfly nymphs share a rock with some cased caddis larvae.
There's a stonefly nymph in the bottom right corner of this picture, but what's really interesting is those white blotches. They're pretty common in my Wisconsin home river river, stuck flat onto the rocks--lots of rocks have a speckled look as a result. They are microcaddis cases, made by larvae of the caddisfly family Hydroptilidae. These are made by larvae of the subfamily Leucotrichiinae, most likely the genus Leucotrichia. They spin little flat oval cases of silk tight and immobile against the rocks.
The mayfly and stonefly nymphs in this picture blend in extremely well.
A large crayfish lurks under a log which is home to several mayfly nymphs and caddisfly larvae.
The strange tubes all over this rock house tiny midge larvae.
A large Ephemerella subvaria nymphs clings to a log along with a couple smaller mayfly nymphs.
A couple Sulphur (Ephemerella invaria) nymphs cling to a log.
An Ephemerella subvaria nymph clings to a white rock in the foreground, and there are other nymphs in the background.
The top of this stump is covered with mayfly and caddisfly life.
This picture shows some of the intricate homes woven by net-spinning caddis larvae.

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