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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.

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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Mayfly Species Callibaetis californicus (Speckled Duns)

This western species is the largest of the Baetidae family. It can be quite common in weedy and cold stillwaters, especially on the West Coast as it's name implies. Initial broods can be 12mm or larger making them easy to recognize. At the lower end of its size range however, it is quite difficult if not impossible for anglers to distinguish from its smaller and more common sibling, Callibaetis ferrugineus hageni. They are so similar in behavior and appearance that discerning the difference is not a factor in angling success. See the Callibaetis Hatch Page for pertinent information.

Where & when

In 8 records from GBIF, adults of this species have been collected during September (38%), April (25%), March (13%), October (13%), and August (13%).

In 1 record from GBIF, this species has been collected at elevation of 1250 ft.

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.

Male Spinner

Body length: 6-8 mm
Wing length: 7-8 mm

A reddish brown species; wing of male not pigmented.

Head and thorax of male dark reddish brown. Fore femur reddish brown; tibia paler red-brown, darker distally, blackish at femoro-tibial joining; tarsus yellowish, joinings narrowly brownish. Middle and hind legs yellowish white; femora with a prominent pre-apical reddish brown band, and streaked longitudinally with red-brown in distal half; 6 to 8 round reddish brown dots along the middle area of each. Tibiae blackish at femoral joining; distal tarsal joint red-brown, other joints reddish apically; joinings narrowly red-brown. Head and thorax of female paler red-brown except the postero-lateral areas of mesonotum; stippled with reddish brown. Fore leg yellowish white, the dark reddish brown femoral band very prominent; apex of tibia, and all of the tarsus except the basal joint, reddish.

Wings hyaline; cross veins few in number (18 to 22 beyond first branch of radius) marginal intercalaries single (see fig. 161); longitudinal veins pale yellowish brown in both sexes; cross veins yellowish in wing of male, and in female wing beyond the disc; those in disc of female wing snowy white. Wing of male not pigmented. Vitta in wing of female rather dark reddish brown, including the basal costal space; cross veins fenestrate with hyaline, those in the costal space to beyond the middle being “short bands from vein to costa,” rather than the usual round or oval spots. Hind margin of vitta “with about 8 or 10 indentations,” those in the basal half quite wide. Hind wing rather narrow for its length, and narrowed toward the tip; reddish brown at extreme base. Cross veins only moderately numerous; usually no marginal intercalary; the costal border distinctly emarginate immediately behind the basal projection.

Abdomen of male reddish brown, paler yellowish brown ventrally; tergites with paler lateral and posterior margins; anterior margin of each very narrowly darker; an indistinct darker line marks the spiracular area; traces of a pale mid-dorsal line. On each tergite and sternite, a pair of reddish brown oblique submedian streaks from anterior margin about to the middle of the segment; one or two dark dots in a line with each dark streak, immediately posterior to it. Median and lateral areas of each segment with red-brown stippling, the dots not very close together. Abdomen of female paler, flesh-colored, but similarly marked. Forceps reddish brown at base, yellowish apically. Tails whitish, joints relatively very long; alternate joinings purplish brown.

Female Spinner

Longitudinal veins pale yellowish brown in both sexes; cross veins yellowish in wing of male, and in female wing beyond the disc; those in disc of female wing snowy white.

Abdomen of female paler, flesh-colored, but similarly marked.

Start a Discussion of Callibaetis californicus


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

Mayfly Species Callibaetis californicus (Speckled Duns)

Species Range
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