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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 Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington
Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
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 albertae (Pink Ladies)

This is one of the two most common Western species of Epeorus, and its spinner falls can be important.

Where & when

Time of year : July through August

Preferred waters: Slower than other mountain Epeorus species

Altitude: 5,000 to 6,000 feet

In 19 records from GBIF, adults of this species have been collected during July (47%), June (26%), September (21%), and August (5%).

In 17 records from GBIF, this species has been collected at elevations ranging from 3248 to 8415 ft, with an average (median) of 5358 ft.

Species Range

Hatching behavior

Water temperature: Warmer than other Western Epeorus species

The Epeorus albertae emergence is usually too sparse to be important.

Spinner behavior

Time of day: Early morning or late afternoon/evening

These are the most fishable events produced by Epeorus albertae.

Nymph biology

Current speed: Fast

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 albertae
Body length: 10 mm
Wing length: 10-11 mm

Eyes of living insect blue-grey. Thorax light brown; mesonotum with a central darker band which spreads out on posterior portion “where there is a median spot of pale ochreous” (McD.). No dark markings on pleura. Legs pale brown; all femora with dark spot near middle. Fore femur and tibia subequal. Tip of fore tibia blackish, other joinings dark brown. Wings hyaline; venation pale brown, fine, inconspicuous; humeral cross vein marked with blackish. Abdominal tergites 2-6 semi-hyaline, slightly smoky; posterior margins narrowly brown. Sternites 2-7 pale hyaline, with faint traces of dark spots at ganglionic areas. Segments 8-10 opaque; tergites brown, sternites creamy. Forceps creamy, brown at apex. Tails brown. Apical margin of forceps base somewhat excavated laterally. Divisions of penes not lobed, as in I. longimanus (now a synonym of Epeorus longimanus); laterally each division is prolonged into a beak-like process; see fig. 107. Median spines rather stout, slightly divergent apically; shorter than in Iron lagunitas (now a synonym of Epeorus lagunitas).

Described as I. youngi

Body length 10 mm, wing length 10-11 mm

Allied to I. albertae (now a synonym of Epeorus albertae), but with shorter fore femur, black spiracular markings and black markings on thoracic pleura.

Head pale yellowish. Thorax fawn-colored. Anterior, posterior and postero-lateral margins of pronotum narrowly black; posterior portion somewhat smoky. Median olive brown streak on mesonotum. Tip of scutellum blackish, also posterior margins of mesonotum and depressions on each side of scutellum. Pale area anterior to scutellum; on each side of this, an olive brown area. Metathoracic scutellum and posterior margin of sclerite blackish. A brownish black streak extends downward from lateral margin of pronotum to base of fore leg. An oblique black streak on pleura anterior to root of fore wing; narrow black pencilings above, anterior and posterior to middle and hind coxae. A small black dot on each coxa. Legs yellowish. A prominent black spot at middle of each femur, and traces of a reddish brown or blackish apical band on each; this may be reduced to a small dark spot on ventral margin. Apex of fore tibia, all claws, and joinings of fore tarsus, blackish. Fore femur about as long as tibia. Femora may be faintly tinged with red. Wings hyaline; venation very pale brown. Basal costal cross veins indistinct, especially at costal margin; cross veins between bulla and stigmatic area obsolescent. Stigmatic cross veins well developed, slightly aslant, not anastomosed, about 14 in number. Humeral cross vein deep purplish black in posterior 2/3 of its length; pale next to costal margin.

Abdominal segments 2-7 semi-hyaline, whitish, faintly washed with pale brown. Posterior margins of tergites narrowly purplish black, most distinct dorsally. Median and lateral areas of tergites faintly brown-shaded; anterior margins and antero-lateral angles pale. A curved black streak, cutting across the postero-lateral angle on each side, divides into two branches at spiracle, so that a pale oval area is enclosed by black lines, as in I. hesperus (now a synonym of Epeorus hesperus). Ganglionic areas on sternites very faintly marked with brown. Abdominal segments 8-10 opaque, fawn-colored like thorax. Tails pale brown; apical portion of each joint is slightly deeper brown. Genitalia very much as in I. albertae (See fig. 107).

The black markings on thorax and spiracular areas of abdomen, and the more distinct median femoral spot, distinguish this species from I. albertae and I. lagunitas (now a synonym of Epeorus lagunitas). The fore femur is also shorter than in the former species. The very indistinct costal cross veins basal of the stigmatic area separate this species from I. sancta-gabriel (now a synonym of Epeorus hesperus) to which it is closely allied. It seems to be allied also to I. hesperus (now a synonym of Epeorus hesperus) but the dark posterior margins of the tergites and the faint brown markings at ganglionic areas of sternites should distinguish it from that species.

Specimens of the Mayfly Species Epeorus albertae

1 Male Dun
3 Female Duns
5 Male Spinners
3 Female Spinners
1 Nymph

Start a Discussion of Epeorus albertae


Mayfly Species Epeorus albertae (Pink Ladies)

Species Range
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