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.
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This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
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Insect Order Coleoptera (Beetles)
The common terrestrial forms are especially important during the late summer when they get knocked into the stream in any number of ways. As far as I know there are no specific life cycle habits which toss these insects into the water in great numbers; they just become important because there are so many of them around incidentally.
Trout generally relish beetles and their imitations make great searching patterns.
Specimens of Beetles:
3 Adults
You wouldn't know to look at it, but this is an aquatic beetle and it's in water in the photographs.
This is an iridescent green terrestrial beetle. They're common in northern Wisconsin's forests during the middle of summer, and I found them on the water's surface more than any other terrestrial insect. I saw the trout take a few and caught some trout on an imitation.
This is a water beetle. It is the hardest object in the world to pick up with tweezers. The second hardest is Mount Everest.
7 Larvae
Every picture of this Psephenidae larva was taken with my old C740UZ through a microscope.
This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
1 Streamside Picture of Beetles:
Many beetles of this species were jumping around the rocks like popcorn on a mid-April afternoon. I'm sure they end up in the water for the trout at times.
In this picture: Insect Order Coleoptera (Beetle).
1 Underwater Picture of Beetles:
Discussions of Coleoptera
Family
1 replies
Posted by DMM on Nov 26, 2006 in the family Hydrophilidae
Last reply on Nov 29, 2006 by Troutnut
I noticed the ending of the family is reversed--should be -ae.
Start a Discussion of Coleoptera
References
- Merritt R.W., Cummins, K.W., and Berg, M.B. 2019. An Introduction to the Aquatic Insects of North America (Fifth Edition). Kendall/Hunt Publishing Company.
- Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.
Insect Order Coleoptera (Beetles)
Taxonomy
Family in Coleoptera
Amphizoidae
1
5
CurculionidaeWeevils
1
3
ElmidaeRiffle Beetles
1
14
HydrophilidaeGiant Water Scavenger Beetles
1
2
PsephenidaeWater Pennies
3
12
26 families (Anthicidae, Carabidae, Chrysomelidae, Dryopidae, Dytiscidae, Georyssidae, Gyrinidae, Haliplidae, Heteroceridae, Hydraenidae, Hydroscaphidae, Hygrobiidae, Lampyridae, Limnichidae, Lutrochidae, Melyridae, Microsporidae, Noteridae, Ptiliidae, Ptilodactylidae, Salpingidae, Scirtidae, Staphylinidae, Staphylinidae, Tenebrionidae, and Torridinicolidae) aren't included.