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.
Featured on the forum
This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
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.
Insect Order Lepidoptera (Moths)
Many species, of course, are not aquatic at all.
Hatching behavior
The pupae of aquatic moths turn into adults underwater in their cocoons, so they are not worth imitating. The emerging adults, swim away from their pupal cocoons and are vulnerable to trout until they crawl or fly away from the water.Egg-Laying behavior
Time of day: Usually dusk or nighttime
Because almost all of the action is at dusk and later, anglers don't realize how prolific these insects really are.
Larva & pupa biology
Diet: Algae and plankton
Shelter type: Some build silk shelters.
Specimens of Moths:
3 Adults
In the field, I accidentally mistook this moth for a weird-looking caddisfly. Only later did I notice the moth mouthparts and that the "hair" on the wings is actually tiny, flat scales.
I have been told this is the only western aquatic moth, Petrophila confusalis, see here on milkweed blossoms.
1 Larva
I caught this inchworm lowering itself to the surface of a trout stream from its silk thread. I saw a couple others floating on the surface, so it's likely the trout were familiar with them.
1 Streamside Picture of Moths:
Start a Discussion of Lepidoptera
References
- LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
- Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.
Insect Order Lepidoptera (Moths)
Taxonomy
Family in Lepidoptera
GeometridaeInchworms
1
7
Family in Lepidoptera: Geometridae
12 families (Arctiidae, Cosmopterigidae, Cosmopterigidae, Cossidae, Gelechiidae, Nepticulidae, Nepticulidae, Noctuidae, Olethreutidae, Pyralidae, Sphingidae, and Tortricidae) aren't included.