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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 Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington
As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.
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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Freshwater Invertebrate Underwater Pictures

Freshwater Invertebrate Underwater Pictures

Underwater photos of freshwater invertebrates in their natural habitat.

Hundreds of cased caddisfly larvae live on this log in a small brook trout stream.

From Eighteenmile Creek in Wisconsin
This is my favorite underwater picture so far. It shows a bunch of Simuliidae (black fly) larvae clinging to a rock and swinging in the fast current. There are also at least four visible mayfly nymphs, probably in the family Baetidae.

From Eighteenmile Creek in Wisconsin
Several Baetidae nymphs line up on a rock.

From Mongaup Creek in New York
This is a close-up underwater view of a stillborn Ephemerella subvaria (Henrickson) female dun.

From the East Branch of the Delaware River in New York
A Brachycentrus "Apple Caddis" pupa scoots around in the surface film.  Apparently it had some difficulty emerging, so I was able to slip my camera underneath it and take a picture from below.

From the East Branch of the Delaware River in New York
This picture from below shows a stillborn Ephemerella subvaria (Hendrickson) dun drifting on the surface amidst a number of shed pupal skins from Brachycentrus caddisflies which were heavily hatching that day.

From the East Branch of the Delaware River in New York
There are several mayfly and stonefly nymphs clinging to this log.

From Eighteenmile Creek in Wisconsin
This Brachycentrus "Apple Caddis" struggled more than its kin in escaping its pupal skin, enabling me to take an underwater picture of it from directly below.  This is sort of a trout's eye view, but I used the flash for the picture so the transparent shuck appears far brighter than it really is.

From the East Branch of the Delaware River in New York
There's a large Ephemerella subvaria nymph in the top left.
The white blotches on this rock are Leucotrichia caddisfly cases, and the wispy tubes are cases made by a type of midge.
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.
The West Branch of the Delaware River in New York
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.
Cased caddis larvae blanket this section of stream bottom.

From Eighteenmile Creek in Wisconsin
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