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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
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.

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.
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 Megarcys irregularis (Rainier Springflies)

Species Range

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.

Source: Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae)

(Figs. 12, 24, 30, 36, 42, 48, 60, 70, 84 a-b, Table 1)Source: Larvae Of The Nearctic Species Of The Stonefly Genus Megarcys Klapálek (Plecoptera: Perlodidae)

Characters. Head capsule width male 3.06 - 3.30 mm, female 3.90 - 4.62 mm; pronotal width male 2.88 - 3.12 mm, female 3.36 - 4.08 mm; body length male 18.3 - 19.5 mm, female 19.5 - 24.0 mm (Table 1). Color and pigmentation (Figs. 12, 24, 30, 36, 42, 48), lacinia, and dorsomesal band of erect silky white hairs typical of genus. Wing pads of male and female macropterous. Gill number and arrangement typical of genus (Fig. 70). Submental gill length male 0.12 - 0.42 mm, female 0.36 - 0.45 mm; anterior supracoxal gill length male 0.27 - 0.42 mm, female 0.36 mm (Table 1). Legs (Fig. 30) with setation typical of genus as described by Stewart & Stark (2002). Y-arms of mesosternum (Fig. 36) typical of genus. Cercal segments male 24 - 26 (Table 1), with setation typical of genus. Developing membranous, windsock-like process of male epiproct (Figs. 42, 48, 70) evident in late instar individuals, and pointed posteroventrally in lateral view (Fig. 79). Developing female subgenital plate of 8 th sternum (Figs. 49, 84 a, b) shallowly notched mesally.


Start a Discussion of Megarcys irregularis

Stonefly Species Megarcys irregularis (Rainier Springflies)

Taxonomy
Species Range
Common Name
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