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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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Dorsal view of a Stenacron interpunctatum (Heptageniidae) (Light Cahill) Mayfly Nymph from the Marengo River in Wisconsin
Posts: 1
Chadwick on Jul 1, 2009July 1st, 2009, 12:19 pm EDT
I would like to know the best way to present the nymph and in which section of the river. Should they be dead drifted mid riffle, swung through tail out ect.
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"Bear Swamp," PA

Posts: 1681
GONZO on Jul 2, 2009July 2nd, 2009, 11:12 am EDT
Hi Chadwick,

Although heptageniids can swim, they generally do it out of the current. If you were to rate the swimming ability of mayfly nymphs, Isonychia would be Michael Phelps, and most heptageniids would be something like the fat kid in remedial gym class. When you watch heptageniids like Stenacron, Maccaffertium, or Stenonema in aquaria, they often try to cling to airstones or, in the absence of stones or other debris, to each other. However, when they get caught in the turbulence created by the airstone without first getting a good grip, they usually freeze and drift in a kitelike manner until they are free of the current. Then they might swim around awkwardly until they regain a foothold on something.

So, clinger nymph imitations presented in stronger current should usually be dead-drifted with at most an occasional feeble twitch. A gentle twitching lift or swing would be imitative as the nymph moves into emergence sites near edges, eddies, or slack areas around boulders.

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