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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.

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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

True Fly Family Tipulidae (Crane Flies)

Tipulidae (Crane Fly) True Fly Adult from Brodhead Creek in Pennsylvania
Craneflies are only occasionally important. There are rumors of fishable mating flights, but most anglers will not encounter them. The larvae are probably the most important stage in the trout's diet.

Hatching behavior

Craneflies pupate for one to three weeks. The species which do so in the water then swim to the surface to emerge in the style of caddisflies, and are presumably vulnerable to trout, though I have not read about good fishing during these events.

Swisher and Richards in Selective Trout say the larvae all crawl out of the water to pupate, conflicting with the above account. There are so many species that it seems likely both behaviors occur in some species.

Egg-Laying behavior

Adult craneflies are occasionally important during their mating flights when their clumsy flying can crash them by accident into the water. Windy days may also blow them in.

Larva & pupa biology

Diet: Mostly vegetation

Many cranefly species live in many different underwater habitats, and others live in moist soil nowhere near the dirt. We anglers are only concerned with the former.

They live as larvae for about a year and sometimes the larvae end up in the drift in good enough numbers to get the trout excited. Buggy grub-like flies are locally known to perform well on certain rivers, and this may be due to a good population of drifting cranefly larvae (or perhaps I speculate too far). In general, larvae are more likely to be important than the adults.

Ernest Schwiebert notes in Matching the Hatch that they are most common in trout stomachs after the water has been high.

Specimens of Crane Flies:

4 Adults
7 Larvae

1 Streamside Picture of Crane Flies:


Start a Discussion of Tipulidae

References

True Fly Family Tipulidae (Crane Flies)

Taxonomy
5 genera (Brachypremna, Ctenophora, Holorusia, Nephrotoma, and Tipula) aren't included.
Common Name
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