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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 Skwala (Perlodidae) (Large Springfly) Stonefly Nymph from the Yakima River in Washington
This Skwala nymph still has a couple months left to go before hatching, but it's still a good representative of its species, which was extremely abundant in my sample for a stonefly of this size. It's obvious why the Yakima is known for its Skwala hatch.
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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Artistic view of a Male Hexagenia atrocaudata (Ephemeridae) (Late Hex) Mayfly Spinner from the Namekagon River in Wisconsin
Posts: 1
Fishcraze on May 27, 2009May 27th, 2009, 6:13 am EDT
I know in North Alabama these flies usually hatch in Jun. What climate/water temperatures are required for hatching? Does it normally have to be dry/no rain for a week?

Thanks to anyone who can answer these questions. I promised my 12 year old, I was going to take him this year and I'm trying to plan my leave at the closest possible time.

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"Bear Swamp," PA

Posts: 1681
GONZO on May 27, 2009May 27th, 2009, 6:51 am EDT

Assuming that you are referring to Hexagenia hatches and not mayflies in general, the Hex hatches are typically quite lengthy--often lasting a month or more. You should not have too much trouble timing the hatch. Cooler than normal long-term weather patterns might delay the onset the hatching period a bit, and warmer than normal weather might accelerate it. Daily weather during the hatching period will influence the concentration and quality of the hatch. I find that the heaviest Hexagenia hatches usually occur on fairly hot days, but the sparser hatches on cooler, overcast days sometimes provide more time to fish. The concentrated, explosive hatches that often occur on warm evenings happen around (or after) dark and can be over in half an hour.

Posts: 115
Trtklr on May 31, 2009May 31st, 2009, 7:12 am EDT
in june if its been "normal" weather i wait for a few hot, humid days and warm nights, then i know its time. this year with the global cooling thats been going on things are running 2-3 weeks behind.
I have seen nothing more beautiful than the sunrise on a cold stream.

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