Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin

Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Cedar sweepers line the fertile spring creek headwaters of a famous trout stream.

From the Bois Brule River in Wisconsin

Stream photos

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Kogotus Stonefly Nymph Kogotus Stonefly Nymph

Dorsal view of a Kogotus (Perlodidae) Stonefly Nymph from Mystery Creek #199 in Washington

This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.

8 Recently Added Photos

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 Metretopus borealis (Pseudo-Gray Drakes)

Where & when

In 32 records from GBIF, adults of this species have mostly been collected during July (38%), August (28%), June (25%), and September (6%).

In 279 records from GBIF, this species has been collected at elevations ranging from -30 to 3524 ft, with an average (median) of 919 ft.

Species Range

source

Map of specific collection sites

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 Metretopus norvegicus

Body length: 10 mm
Wing length: 9 mm

A brownish species, the middle abdominal segments of the male translucent; only species of the genus known in North America.

Thorax pitch-black above. Body somewhat discolored. Abdominal segment 1, and segments 7-10, bistre brown; the middle segments translucent. Posterior margins of tergites narrowly marked with umber brown. Mid-dorsal line of the same color, also “an oblique linear lanceolate streak on each side produced forwards from it, so as to constitute a tridentate marking, enclosing on each side of the dorsum a large almost right-angled triangular translucent space, rounded at the posterior angle, the shortest side of which is at the base of the segment. From the right angle of this triangle a fine tapering blackish streak proceeds towards the middle of the hypotenuse” (Eaton). Tails uniformly dark grey. The apical margin of the ninth sternite of the female is entire, and convex. The penes are divided half way to the base; each free portion is rather linear, and directed slightly outward, having a rounded lobe on the inner apical margin (see fig. 114).