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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.

Dorsal view of a Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington
As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.
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 Nixe rusticalis

Where & when

In 33 records from GBIF, adults of this species have been collected during July (55%), August (27%), June (12%), and September (6%).

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 Heptagenia rusticalus
Body length: 5 mm
Wing length: 5 mm

Mesonotum brown; abdominal tergites largely brown, paler laterally; genitalia of lucidipennis (now a synonym of Nixe lucidipennis) type.

Head brown between the eyes, becoming yellowish anteriorly; ochreous shading at bases of antenna. Pronotum brown, shading into yellowish on the lateral margins. Mesonotum brown, likewise metanotum. Pleura and sternum paler, dull yellowish; tinges of brown on pleura. Legs dull yellowish, like sternum in color; femora with slight tinges of brown, fore tarsus suffused with pale smoky. Basal joint of fore tarsus about 1/4 of the second; on hind leg, basal tarsal joint longer than the second. Wings hyaline; longitudinal veins faint, cross veins almost invisible except those of the costo-apical space, which are 5 or 6 in number.

Abdomen largely brown dorsally, paler laterally; segments 1-6 semi-hyaline, 7-10 opaque and somewhat ruddier in color dorsally. Each tergite with faint pale middorsal line bordered by a pair of indistinct pale submedian streaks, not attaining the posterior margin, and most distinct on the anterior tergites. In transmitted light a small pale antero-lateral patch and a larger postero-lateral one are visible, separated by a narrow brown strip. Sternites dull dirty yellowish, tinged with ruddy on the posterior segments. Forceps and tails pale smoky. Apical inner projection of each division of penes less prominent than in H. lucidipennis (now a synonym of Nixe lucidipennis); the lateral margin drawn out into a slight hook, much as in the H. maculipennis (now a synonym of Leucrocuta maculipennis) group, which character is not found in lucidipennis or H. inconspicus (now a synonym of Afghanurus inconspicua). Subapical spines on the ventral surface near outer margin usually small (see fig. 97).

This species, intermediate between lucidipennis and inconspicus, is smaller than the former, likewise somewhat darker in color and with clearer abdominal markings. It is considerably darker than the latter species, and differs in details of genitalic structure.

Start a Discussion of Nixe rusticalis


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

Mayfly Species Nixe rusticalis

Species Range
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