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.

Upper Titcomb Lake

From Titcomb Basin in Wyoming

Stream photos

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Neoleptophlebia Mayfly Nymph Neoleptophlebia Mayfly Nymph

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington

Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.

10 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.

A good Dicosmoecus discussion

This topic is about the Caddisfly Genus Dicosmoecus

This is a superhatch in the West. Gary LaFontaine had a self-proclaimed obsession with Dicosmoecus, and he devotes several pages of Caddisflies to stressing the importance of its larvae, pupae, and adults. He wrote:

The question for fly fishermen seeking big trout is: "Which insects provide the best opportunity for catching such fish?" My list would be: Giant Orange Sedge (Dicosmoecus sp.), Salmon Fly (Pteronarcys californica, a stonefly), and the Michigan Mayfly (Hexagenia limbata). Dicosmoecus is the most important -- and the contest is not even close.

His reasons for this judgement are five traits of Dicosmoecus:

Very large size: Adults 30mm long, and thick.

Activity concentrated within 2-3 weeks.

Emerges in the low, clear water of fall.

Active during afternoon and evening.

Abundant in rivers with sea-run trout.

Personally I have only caught a good Dicosmoecus hatch one time, and on a secret desert spring creek. It reminded me of fishing Isonychia mayfly hatches back east, because there weren't enough bugs around to have trout rising consistently, but the presence of a particularly good food source in low numbers for a long time had them on the lookout for imitations. I had big trout cartwheeling out of the water to smash actively-fished imitations.

Example specimens

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Female Dicosmoecus gilvipes (October Caddis) Caddisfly Adult

Female Dicosmoecus gilvipes (Limnephilidae) (October Caddis) Caddisfly Adult from the South Fork Snoqualmie River in Washington

I've been hoping to add a really good October Caddis to the photo collection here for years, but so far I had struck out on finding them on the river. Tonight, this one flew into the kitchen during a pizza party at a house along the river, and was quickly pointed out -- one of the perks of hanging out with other aquatic biologists! Maybe next year I can finally get a salmonfly on taco night or something.

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Female Dicosmoecus atripes (October Caddis) Caddisfly Adult

Female Dicosmoecus atripes (Limnephilidae) (October Caddis) Caddisfly Adult from the St. Joe River in Idaho

This specimen is 26 mm. - Entoman

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Dicosmoecus gilvipes (October Caddis) Caddisfly Adult

Dicosmoecus gilvipes (Limnephilidae) (October Caddis) Caddisfly Adult from the Touchet River in Washington

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Aug 22, 2006August 22nd, 2006, 3:42 pm EDT

There's a good topic with people sharing their experiences with Dicosmoecus over at the Washington Fly Fishing Forum.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Aug 22, 2006August 22nd, 2006, 7:40 pm EDT

Jason-

In case you're not familiar with the cast of characters on WFF, that particular thread drew several pretty savvy members. Preston is Preston Singletary a columnist with Flyfishing & Tying Journal. Smamla (as in S. malma) is Curt Kramer, a retired WDFW fisheries biologist and renowned Bull Trout enthusiast.

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com