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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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Caddisfly Genus Mystacides (Black Dancers)

Where & when

Time of year : Summer

This genus is represented across the continent, but the Western species Mystacides alafimbriata is probably the most prominent.

In 111 records from GBIF, adults of this genus have mostly been collected during June (27%), August (25%), July (24%), May (14%), and September (7%).

In 35 records from GBIF, this genus has been collected at elevations ranging from 3 to 3873 ft, with an average (median) of 1181 ft.

Genus Range

Hatching behavior

Time of day : Morning

Black Dancers emerge by crawling out onto rocks or other protruding objects, so emergence is not terribly important.

Egg-Laying behavior

Time of day: Dusk

The females dive to lay their eggs on the bottom.

Larva & pupa biology

Shelter type: Long, thin cases made of various debris. The case may be three times as long as the actual insect.

Specimens of the Caddisfly Genus Mystacides

3 Adults
2 Male Adults

Discussions of Mystacides

Does anyone have success fishing this hatch?
9 replies
Posted by Troutnut on Sep 24, 2006
Last reply on Jan 14, 2011 by PaulRoberts
I've been extremely frustrated several times by trout feeding on Black Dancers, especially on the Brule in Wisconsin. The flies gather in little swarms beneath overhanging alders along the bank, usually within a foot or two of the surface, and "dance" around. A trout or two, usually small, will appear below them and rise steadily.

This is one of the most reliable insect activities on that river in the summer. It's quite unlike any other hatch, since it never affects most of the stream. Instead, there are just little pockets of activity here and there along the bank. It would be interesting to see if some of the trout are Mystacides "specialists" who are conditioned to cruise the banks looking for this food source.

At any rate, I've never had much luck catching these trout. I've tried most often on the Brule but I've run across similar situations on Finger Lakes and Catskill rivers in New York, too. Has anyone cracked the code?

Start a Discussion of Mystacides


Caddisfly Genus Mystacides (Black Dancers)

Genus Range
Common Name
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