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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.

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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Stonefly Species Sweltsa onkos (Sallflies)

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 Eight Eastern North American Sweltsa (Plecoptera: Chloroperlidae)

Mature larva. Body length 7.5 - 8.5 mm. General color brown, abdomen chestnut brown; body without distinctive pattern except underlying adult features in pharate individuals. Thorax and abdomen covered with abundant dark clothing hairs. Pronotum bearing ca. 20 anterolateral setae, and ca. 19 posterolateral setae; both rows extend to near median suture (Fig. 21). Mesonotum bearing ca. 13 outer marginal setae and a few inner marginal setae (Fig. 22). Foreleg with sparse femoral and more extensive tibial fringe setae; femora with ca. 5 long thick setae on dorsal margin and ca. 9 on ventral margin (Fig. 23); tibiae bearing 3 - 4 long thin outer marginal setae and ca. 5 inner marginal thick setae. Abdominal tergum 8 with posterior fringe complete; mesally fringe includes mixed thin and thick setae (Fig. 24); lateral intercalary setal cluster includes ca. 14 thick setae. Cerci with ca. 14 - 15 segments; long dorsal setae in apical segmental whorls about as long as two segments (Fig. 25).

Specimens of the Stonefly Species Sweltsa onkos

1 Adult

Start a Discussion of Sweltsa onkos

Stonefly Species Sweltsa onkos (Sallflies)

Taxonomy
Species Range
Common Names
Resources
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