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.

Stream photos

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.

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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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Baetidae (Blue-Winged Olive) Mayfly Nymph Pictures

This Baetis nymph is quite a bit larger than any of the others I found in winter 2004. Abdomen segment 5 is only slightly pale while 9 and 10 are quite pale. The tail is banded at the tip. Its body measures about 9mm long. It's much larger than the other Baetis specimens I collected, and it has quite well-developed wingpads.

It's most likely a mature nymph from a very early-hatching brood. It comes from the headwaters of a very small, very spring-fed Lake Superior tributary, which wasn't at all frozen despite very frigid temperatures and 3 feet of snow on the ground.

This mayfly was collected from Schacte Creek, Bayfield County in Wisconsin on February 5th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.

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