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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 Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington
This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
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 Neoleptophlebia heteronea (Blue Quills)

This species is the primary spring emerging Paraleptophlebia throughout the western region. Outside of California and parts of Oregon, if you run into a little blue winged brown bodied fly with three tails in the spring, it's probably this.

Where & when

Time of year : Spring or early summer

Preferred waters: Rivers of all speeds and sizes

I collected one specimen on the Madison River, Montana on July 1st.

In 9 records from GBIF, adults of this species have been collected during June (67%), May (22%), and August (11%).

In 8 records from GBIF, this species has been collected at elevations ranging from 6535 to 10387 ft, with an average (median) of 8671 ft.

Species Range

Hatching behavior

Time of day : Afternoon

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 Paraleptophlebia heternea
Body length: 5-6 mm
Wing length: 6-7 mm

This is a blackish species with brown-and-white ringed abdomen. The top of head and thorax are rich reddish brown, the sides duller. The fore legs are brown, with paler tarsi and the other legs are wholly pale. The wings are whitish with cross veins absent from most of the costal space, with only a few irregular ones in the stigmatic region. The basal segment of the abdomen and the three apical ones are brown. The middle segments are paler, whitish at the base with the rings broader on segments 4 and 5 and disappearing on 7, and the black spiracles have a broken line connecting them. Basal segment of the forceps rather broad, then nearly parallel-sided to the middle, then strongly tapering; the 3rd segment is nearly as long as the 2nd but much more slender. The penes are separated by a V-shaped notch. The sperm ducts terminate in a projecting tube that is longer than the spines at its outer side, and that has its outer cavinate margin revolute (see fig. 134).

Specimens of the Mayfly Species Neoleptophlebia heteronea

5 Male Spinners

Start a Discussion of Neoleptophlebia heteronea


Mayfly Species Neoleptophlebia heteronea (Blue Quills)

Species Range
Common Name
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