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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 Glossosoma (Glossosomatidae) (Little Brown Short-horned Sedge) Caddisfly Larva from the Yakima River in Washington
I caught this tiny larva without a case, but it seems to key pretty clearly to to Glossosomatidae. From there, the lack of sclerites on the mesonotum points to either Glossosoma or Anagapetus. Although it's difficult to see in a 2D image from the microscope, it's pretty clear in the live 3D view that the pronotum is only excised about 1/3 of its length to accommodate the forecoxa, not 2/3, which points to Glossosoma at Couplet 5 of the Key to Genera of Glossosomatidae 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 Heptagenia townesi

Where & when

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

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: 11 mm
Wing length: 11-12 mm

A bronzy-brown species allied to Heptagenia marginalis; genitalia of the Heptagenia flavescens type (see fig. 95).

Head deep red-brown on vertex, paler before the ocelli; anterior margin widely black, frontal shelf shaded with blackish. Posterior margin purplish black; black median streak from middle of vertex to posterior margin, with a black submedian streak on each side. Antenna pale basally; filament smoky brown. Pronotum dark red-brown; lateral margin and a prominent lateral streak, black. A purplish streak above and behind fore coxa. Mesonotum deep red-brown, heavily shaded with blackish anteriorly, laterally above wing roots, and on entire posterior margin, including scutellum. Pleura paler red-brown, with wide yellowish areas anterior to and below wing roots. Blackish markings above leg bases as in H. marginalis. Sternum reddish brown, sutures narrowly darker. Fore leg dark bronzy brown; femur darker on each edge, with an indistinct median purplish band, and a semicircular dark mark at apex, as in marginalis; tip of tibia darker. Basal tarsal joint 1/4 to 1/5 of the second. Tarsus about 1 1/2 times as long as tibia. Middle and hind coxae, trochanter and femora pale whitish, the femora largely washed with purplish grey; margins and apical markings as in fore femur, also two indistinct longitudinal streaks; median band almost obsolescent. Tibiae and tarsi pale smoky brown, tarsal joinings darker.

Wings hyaline. Costa, subcosta and radius heavy, dark red-brown, almost black basally; cross veins in first two spaces similar, but not margined. All other veins finer, red-brown. Apical portion of costal space tinged with brownish; basal portion before humeral cross vein tinged with purplish. 5 to 6 cross veins in costal space before bulla, 19-22 beyond it.

Abdominal tergites 1-7 light yellowish to bronzy brown, semi-hyaline; 8-10 brighter with tinge of reddish, opaque. Posterior margins widely blackish; blackish wedge-shaped longitudinal stripes, one on each side, the wide part of each wedge directed forward. Traces of a blackish geminate mid-dorsal line, most distinct on 6 and 7, obsolescent on 4, 5, 8 and 9. Faint yellowish submedian triangles based on the posterior margin, are evident on some tergites. Sternites yellowish white, 9 red-brown; posterior margins greyish brown; on each sternite are two dark dots near the center, one on each side of median line, and two dark oblique submedian streaks from the anterior margins. Forceps and tails dark reddish to smoky brown. Penes quite similar to those of H. marginalis; second forceps joint relatively longer than in that species.

The slightly larger size, dark bronzy color and ventral abdominal markings distinguish this species from H. marginalis; it is considerably larger than the pale Heptagenia dolosa, another allied species.

Start a Discussion of Heptagenia townesi


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

Mayfly Species Heptagenia townesi

Species Range
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