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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

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 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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Lateral view of a Hydropsyche aenigma (Hydropsychidae) (Spotted Sedge) Caddisfly Adult from the West Branch of the Delaware River in New York
These big caddisflies were tempting trout as they wriggled out of their shucks, while others skated across the water at a medium pace, probably egg-laying.
Troutnut's profile picture
Bellevue, WA

Posts: 2758
Troutnut on May 18, 2007May 18th, 2007, 1:43 pm EDT
I'm really just guessing. I'm too busy too key it out right now but I'd really like to know what it is. This was one of the main species the fish were taking (along with Apple Caddis) on the West Branch of the Delaware the other day.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Taxon's profile picture
Site Editor
Plano, TX

Posts: 1311
Taxon on May 18, 2007May 18th, 2007, 4:22 pm EDT
Sure looks like Hydropsyche to me. There are ~13 species in NY, and I don't have access to species keys. However, I suppose H. betteni can be eliminated as a possibility, as your specimen would be too short for that species.
Best regards,
Roger Rohrbeck
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on May 20, 2007May 20th, 2007, 8:49 am EDT
If I'm reading the wing venation correctly in photo #16, this looks like Ceratopsyche.
Grants Pass, OR

Posts: 302
Creno on Dec 22, 2007December 22nd, 2007, 10:10 am EST
Folks - Ceratopsyche - Symphitopsyche - Hydropsyche - just another problem for the splitters. Right now there seem to be two schools and both are represented in the previous postings.

While the photos are some of the best I have seen of the details necessary to make a determination, I cannot quite make out the single final character needed to be sure (the lateral spur on that most intimate of the male parts). But based on what I can see, and the great photo of the goldish spots on the wings I would suggest Hydropsyche (Ceratopsyche) aenigma.

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