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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 Paraleptophlebia moerens

Where & when

In 13 records from GBIF, adults of this species have been collected during June (69%), May (15%), July (8%), and April (8%).

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

Body length: 6 mm
Wing length: 6 mm

This is another small, clear-winged species with whitish, cross-lined abdomen. Head and thorax dark brown above. Legs pale. Wings whitish with a milky stigmatic area covering costal and subcostal interspaces. Costal cross veins almost wholly obsolete even in the stigmatic area where their faint vestiges are numerous, simple, and considerably aslant.

Abdomen brown on the ends; segments whitish on 3 to 6; less so on 2 and 7. The dorsal apical cross-bands of the white segments are well marked, as are also the lateral, longitudinal, spiracular lines which meet them at the hind angle of the segments. Forceps with a large basal lobe-like dilatation of its first segment. Penes separated for half their length by an oval notch, the aperture of which is closed by a lobe-like prolongation inward of their distal ends. Outer angle of the tips broadly rounded. The proximal portion of its margin is prolonged forward in an incurved spine; attached to this spine is the usual reflexed spur which is very slender (see fig. 133). Tails white.

Start a Discussion of Paraleptophlebia moerens


Mayfly Species Paraleptophlebia moerens

Species Range
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