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.

Stream photos

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

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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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Stonefly Species Allocapnia harperi (Little Snowflies)

Species Range

source

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Description from GBIFthe Global Biodiversity Information Facility

Source: Epiproct And Dorsal Process Structure In The Allocapnia Forbesi Frison, Allocapnia Pygmaea (Burmeister), And Allocapnia Rickeri Frison Species Groups (Plecoptera: Capniidae), And Inclusion Of Allocapnia Minima (Newport) In A New Species Group

Male epiproct. Apical segment of upper limb ca. 303 µm long, and armed on the apical ca. 186 µm with dense patch of wave-like spikes (Figs. 85 - 88); apical segment ca. 145 µm wide at base, gradually narrowed to a bluntly rounded tip. Basal segment of upper limb ca. 541 µm long and ca. 85 µm wide near mid-length; basal segment bears a shallow, longitudinal groove in basal half. Greatest width of lower limb about as wide as apical segment of upper limb, but not clearly projecting beyond margins of apical segment. Male tergal process. Prominent raised bilobed structure on abdominal tergum 8 (Figs. 89 - 90); process on tergum 8 ca. 256 µm wide and covered with scale-like structures. Lobes of tergum 8 process small, ear-like, directed caudally and obliquely oriented on segment; notch ca. 140 µm.

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