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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.

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington
This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
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 Epeorus dulciana

Where & when

In 1 records from GBIF, adults of this species have been collected during June (100%).

In 1 record from GBIF, this species has been collected at elevation of 1450 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

Described in Needham et al (1935) as Iron dulciana
Body length: 9? mm
Wing length: 9.5 mm

A species of the albertae (now a synonym of Epeorus albertae) group; blackish markings on thoracic pleura; apical margin of forceps base as in I. sancta-gabriel (now a synonym of Epeorus hesperus).

Head yellowish; antennae dusky. Red patches on vertex of head of female, between eyes and ocelli, and posterior to median ocellus; posterior margin of occiput blackish. Thoracic notum pale brown. Lateral and posterior margins of pronotum blackish. A reddish streak on each side of anterior portion of mesonotum. Posterior portions of mesonota and metanota somewhat darker brown; dark median streak on mesonotum. Pleura and sternum yellow-brown. Creamy markings on pleura; a red-brown streak from pronotum to base of fore leg, another anterior to middle leg. Black dots on and above all coxae. Legs yellowish to olive brown. Tip of fore tibia, claws and tarsal joinings blackish brown. Median blackish spot on each femur, also a narrow red-brown apical band. Fore femur very slightly shorter than tibia. Wings hyaline. Venation yellowish in male, cross veins indistinct except those of stigmatic area, which are 9-11 in number. Humeral cross vein black near subcosta.

Abdominal tergites yellowish to olive brown; posterior margins narrowly blackish. Sternites slightly paler. Tails yellowish to olive brown, joinings faintly darker. Genitalia as in fig. 107, "n. sp., McD.” The black thoracic markings ally this species to I. sancta-gabriel and I. youngi (now a synonym of Epeorus albertae). Differences in detailed structure of the penes separate it from both species; the pale venation of the male also serves to distinguish it from the former species. The apical margin of the forceps base is much more produced than in I. youngi.

Female Spinner

Described in Needham et al (1935) as Iron dulciana
Body length: 9? mm
Wing length: 9.5 mm

In female, venation rather dark brown; veins fine but distinct.

Start a Discussion of Epeorus dulciana


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

Mayfly Species Epeorus dulciana

Species Range
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