Header image
Enter a name
Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
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 Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen appears to be of the same species as this one collected in the same spot two months earlier. The identification of both is tentative. This one suffered some physical damage before being photographed, too, so the colors aren't totally natural. I was mostly photographing it to test out some new camera setting idea, which worked really well for a couple of closeups.
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 Cinygmula par

I have not found any specific information about this species in the fly fishing literature, but I did encounter a spinner swarm plentiful enough to make for great fishing in the right kind of stream. However, this was happening at dusk in a stream where the biggest trout were seven inches long and they would all charge any dry fly that hit the water, hatch or no hatch.

Where & when

Time of year : Summer

In 6 records from GBIF, adults of this species have been collected during August (50%), September (17%), June (17%), and July (17%).

In 8 records from GBIF, this species has been collected at elevations ranging from 1000 to 10971 ft, with an average (median) of 8701 ft.

Species Range

Spinner behavior

Time of day: Dusk

Habitat: Riffles

I observed a swarm of thousands of Cinygmula par spinners gathered over a riffle at dusk on a small stream on the east slope of Washington Cascades on July 4th.

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: 8-9 mm
Wing length: 9-10 mm

A medium-sized species, wings tinged with light grey, darker at bases; dark midventral ganglionic marks.

Thoracic notum light pitch-brown, “sometimes approaching light luteo-piceous anteriorly at the sides” (Eaton). Legs sooty to golden brown; base of fore femur and trochanter somewhat paler, base of first fore tarsal joint darker. Wings hyaline, “tinted with light bistre-grey throughout, but with a stronger tint than elsewhere” at the wing roots and in the stigmatic area; near wing roots the color becomes rather dark brown. Venation yellowish brown.

Abdominal segments 2-7 semi-hyaline; tergites largely light brown, the anterior margins, antero-lateral areas, narrow median line and submedian streaks being hyaline, “dirty-whitish.” The three pale longitudinal streaks are outlined in darker color. Sternites paler, the ganglionic areas on 3-7 conspicuously marked with sepia-brown. Segments 8-10 opaque; tergites “Vandyke-brown,” sternites “very light brownish ochre” (Eaton). Tails brown. A large spine on lower outer margin of penes on each side, smaller spine on inner margin (see fig. 103).

This species is allied to both C. confusa and C. hyalina (both now a synonym of C. par), also to the eastern C. atlantica (now a synonym of Cinygmula subaequalis). Distinguishing features are indicated under each of these species.

Described as C. confusa

Body length 9 mm, wing length 10 mm

A rather large species with amber-tinged wings; spines on inner and lower outer margins of penes; purplish mid-ventral patches on hyaline segments.

Head deep red-brown. Thorax light olive brown, the central portion of notum shaded with darker brown; purplish tinges on prothorax, and on pleura below the wings. Coxae of all legs light brown. Fore femur deep purplish, remainder of fore leg blackish; middle and hind legs light purplish brown. Wings “evenly suffused with deep amber color, with dark, clean cut venation” (McD.). Abdominal segments 2-7 hyaline. Posterior half of each tergite purplish brown; indistinct pale submedian streaks outlined in brown are most evident on tergites 2 and 3; on these tergites also, the brown band is wider than on the following segments. Sternites 2-7 with midventral purplish patches, one on each segment. Segments 8-10 opaque, light brown; tergites with slight purplish shading; sternites somewhat paler than tergites. Forceps smoky brown basally; tails deep blackish brown. A spine on inner margin, another on lower outer margin of each side of penes (see fig. 103).

This species is allied to C. hyalina (now a synonym for C. par) and Cinygmula par. The deep amber tinge of the wings distinguishes it from both of these species. The purplish tinge of the fore femur likewise separates it from C. hyalina; the fore leg of C. par is much lighter in color.

Described as C. hyalina

Body length 9? mm, wing length 10? mm

A species with untinted wings; spines on inner and lower outer margins of penes.

The description of this species is largely comparative, with only points of distinction between this and C. confusa (now a synonym of C. par) being indicated. Said to be very similar to confusa in general appearance, but with hyaline wings, tinted very slightly in the stigmatic area only. Thorax somewhat deeper in color than in confusa; legs light to deep brown, but lacking the purple tinge of that species. Tergites 2 and 3 almost entirely brown, with faint traces only of the pale submedian streaks. Posterior margins of tergites brown, with less purplish tinges, and the “definition between the pale and dark areas is less distinct” (McD.). Sternites suffused with whitish, appearing more opaque than in confusa. Penes very similar in structure, but the basal spine on the lower outer margin is relatively longer and straighter, and the divisions of the penes relatively stouter, than in C. confusa. (See fig. 103).

This species is allied also to C. par, from which it may be distinguished by the paler wings and less extensive brown shading on abdominal tergites.

Specimens of the Mayfly Species Cinygmula par

2 Male Spinners
1 Female Spinner

1 Video of Cinygmula par Mayflies:

Cinygmula par mating flight

It's remarkable what thick hatches, and especially spinner flights, can come from a species few anglers have ever heard of. The genus Cinygmula is thought to produce unremarkable spinner flights, but this one would certainly have gotten the trout going if it weren't happening just before dark on a small stream where there isn't a lot of nocturnal feeding.

Start a Discussion of Cinygmula par


  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Mayfly Species Cinygmula par

Species Range
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy