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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.

Lateral view of a Male Callibaetis ferrugineus (Baetidae) (Speckled Dun) Mayfly Spinner from Mystery Creek #304 in Idaho
This is one of four specimens I photographed together from the same hatch, also including a nymph, a male dun, and a female dun. According to the key in Check (1982), the clear wing venation on the associated dun shows that it is either Callibaetis ferrugineous or Callibaetis pallidus, and the characteristics to tell the difference between those two are maddening for both the nymph and adult. If the partial shading in the wing is "medium to dark brown," and the dots on the body are "fuscous to dark brown," then it's ferrugineous. If the wing shading is "chestnut brown" and dots on the body are "yellowish to chestnut brown," then it's pallidus. However, several spare specimens I collected alongside the one in the photo have no markings on the wing at all, which would seemingly indicate ferrugineous according to the key. It's enough for a contingent ID, but I still wouldn't rule out pallidus.
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 Cinygmula ramaleyi (Small Western Gordon Quills)

This can be the first mayfly of the season on high mountain streams in the western states, but emerges later in the season in Alaska. It is the most important species of Cinygmula for anglers.

Where & when

Time of year : May through August; best in June or July

Cinygmula ramaleyi is widely distributed in the West.

This species appears to be common in interior Alaska, where it emerges during the latter half of the summer. Fishable hatches and selective grayling are possible on a couple of cold, productive spring creeks in the area.

In 10 records from GBIF, adults of this species have been collected during September (30%), August (30%), June (20%), October (10%), and July (10%).

In 9 records from GBIF, this species has been collected at elevations ranging from 2702 to 10492 ft, with an average (median) of 9760 ft.

Species Range

Hatching behavior

Time of day : Late morning

Water temperature: Mid 40°F range and up

Emergence in interior Alaska differs from that described for other locales; I have observed them emerging on a spring creek beginning in July and extending through September. It seems to pick up as the larger Drunella doddsii hatch tapers off, both in terms of season and time of day. Although they are reported as a late morning hatch in angling literature, I have most often observed them in the afternoon or early evening in Alaska. The duns emerge in classic sailboat fashion and take some time to get off the water.

Spinner behavior

Time of day: Midday

Habitat: Riffles

Nymph biology

Current speed: Medium to fast

Substrate: Gravel or rocks

In Mayflies, the Angler, and the Trout, Fred Arbona reports that his stomach samples showed trout feeding heavily on these nymphs during non-hatch periods.

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: 8 mm
Wing length: 10 mm

A medium-sized species with amber-tinged wings; spines on inner margin of penes only.

Head purplish brown. Thorax rather bright red-brown; mesonotum yellowish brown, median stripe darker red-brown. Postero-lateral areas of mesonotum on each side of and posterior to scutellum, and lateral areas of metanotum, purplish brown. Narrow purplish markings above leg bases. Median area of mesosternum darker than pleura. Legs reddish brown; fore leg tinged with smoky. All femora with distinct reddish tinge; apex of fore tibia blackish; femora-tibial joinings purplish brown, tarsal joinings narrowly dark brown, on all legs. Wings hyaline, distinctly amber tinged throughout. Veins rather fine, reddish brown.

Abdominal segments 2-7 and basal portion of 8, semi-hyaline; hyaline areas of tergites light red-brown, the posterior half or two-thirds of each purplish brown. Tergite 2 almost wholly dark except for narrow hyaline anterior margin; 2/3 of tergite 3, and about 1/2 of tergites 4-7, dark-shaded, the dark color often concentrated in postero-lateral areas. Pale submedian streaks outlined in darker color are faintly indicated on basal tergites. Sternites greyish with tinge of pale brown; no distinct darker median markings on 2-6. Segments 9 and 10, and apical portion of 8, opaque; tergites red-brown, sternites paler. Ganglionic areas of sternites 7-9 opaque, pale red-brown. Forceps deep olive or smoky brown; penes light red-brown; a curved spine on inner margin of each side of penes (see fig. 103). Tails deep smoky brown.

Specimens of the Mayfly Species Cinygmula ramaleyi

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

Start a Discussion of Cinygmula ramaleyi


Mayfly Species Cinygmula ramaleyi (Small Western Gordon Quills)

Species Range
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