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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Dorsal view of a Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington
This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
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.

Mayfly Species Tricorythodes stygiatus (Tricos)

Where & when

Time of year : Mid-July through October

This is probably the most abundant species of Tricorythodes in the East and Midwest.

In 7 records from GBIF, adults of this species have been collected during August (43%), July (29%), September (14%), and June (14%).

In 2 records from GBIF, this species has been collected at elevations of 1181 and 3264 ft.

Species Range

Tricorythodes stygiatus Fly Fishing Tips

This species requires a size 24 hook or smaller, unlike Tricorythodes minutus which may sometimes be imitated on a size 20 or 22 hook.

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.

Male Spinner

Body length: 2.5-3 mm
Wing length: 3.5 mm

Mesonotum shiny blackish; thoracic sternum and abdomen dull blackish; hind femora deep rufo-piceous, tibiae largely same color.

Head dull black, the posterior tubercles shiny black; eyes and lateral ocelli black; basal joint of antenna black, paler apically. Median area of pronotum dull black, with faint ruddy tinge in the mid-dorsal portion; shiny black laterally. Mesonotum shiny black, the scutellum with ruddy tinges; pleura shiny black; anterior to the wing roots and around the bases of the legs are dull areas. Sternum dull black. Coxa and trochanter of fore leg black; femur blackish with a pale hyaline streak longitudinally; tibia and tarsus whitish, tinged faintly with ruddy; tibia 1.5 mm. in length. Coxae and trochanters of middle and hind legs blackish, femora shiny rufo-piceous; tibiae largely rufo-piceous, becoming paler apically; tarsi whitish. Wings whitish hyaline; subcosta and radius darker. Abdominal tergites completely suffused with dull blackish, tinged slightly with ruddy in the median area, especially on the basal tergites. Sternites dull blackish; lateral margins somewhat shiny; posterior margins faintly whitish. Genitalia dull whitish (see fig. 160). Tails blackish basally, becoming pale smoky apically.

The black body and deep reddish brown femora separate this from other small species in the genus.


Start a Discussion of Tricorythodes stygiatus

References

Mayfly Species Tricorythodes stygiatus (Tricos)

Taxonomy
Species Range
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