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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Coleoptera (Beetle) Insect Larva Coleoptera (Beetle) Insect Larva

Lateral view of a Coleoptera (Beetle) Insect Larva from Sears Creek in Washington

6 Recently Added Photos

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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Insect Order Coleoptera (Beetles)

Lara (Elmidae) Riffle Beetle Larva from the South Fork Snoqualmie River in Washington

There are about 5,000 species of aquatic beetles, and I won't be including them all on this site. I've also only included certain aquatic beetles and terrestrial families which I've found frequently on trout streams.

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

Coleoptera (Beetle) Insect Adult

3 Pictures

You wouldn't know to look at it, but this is an aquatic beetle and it's in water in the photographs.

Collected January 30, 2004 from unknown in Wisconsin

Added by Troutnut on January 25, 2006

Collected January 30, 2004 from unknown in Wisconsin and added by Troutnut on January 25, 2006

Polydrusus (Weevil) Beetle Adult

3 Pictures

Artistic view of a Polydrusus (Curculionidae) (Weevil) Beetle Adult from the Bois Brule River in Wisconsin

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.

Collected July 30, 2004 from the Bois Brule River in Wisconsin

Added by Troutnut on January 25, 2006

Collected July 30, 2004 from the Bois Brule River in Wisconsin and added by Troutnut on January 25, 2006

Hydrophilidae (Giant Water Scavenger Beetle) Beetle Adult

2 Pictures

This is a water beetle. It is the hardest object in the world to pick up with tweezers. The second hardest is Mount Everest.

Collected January 12, 2004 from the Namekagon River in Wisconsin

Added by Troutnut on January 25, 2006

Collected January 12, 2004 from the Namekagon River in Wisconsin and added by Troutnut on January 25, 2006

7 Larvae

Lara Riffle Beetle Larva

14 Pictures

Dorsal view of a Lara (Elmidae) Riffle Beetle Larva from the South Fork Snoqualmie River in Washington

Collected May 13, 2022 from the South Fork Snoqualmie River in Washington

Added by Troutnut on May 16, 2022

Collected May 13, 2022 from the South Fork Snoqualmie River in Washington and added by Troutnut on May 16, 2022

Psephenus (Water Penny) Beetle Larva

5 Pictures

Here's a "water penny" (a Psephenidae beetle larva) crawling around on a real penny.

Artistic view of a Psephenus (Psephenidae) (Water Penny) Beetle Larva from Fall Creek in New York

Collected March 28, 2006 from Fall Creek in New York

Added by Troutnut on April 6, 2006

Collected March 28, 2006 from Fall Creek in New York and added by Troutnut on April 6, 2006

Coleoptera (Beetle) Insect Larva

3 Pictures

Collected July 24, 2019 from Mystery Creek #249 in Washington

Added by Troutnut on July 26, 2019

Collected July 24, 2019 from Mystery Creek #249 in Washington and added by Troutnut on July 26, 2019

Psephenus (Water Penny) Beetle Larva

3 Pictures

Dorsal view of a Psephenus (Psephenidae) (Water Penny) Beetle Larva from Cascadilla Creek in New York

Collected March 12, 2005 from Cascadilla Creek in New York

Added by Troutnut on April 5, 2006

Collected March 12, 2005 from Cascadilla Creek in New York and added by Troutnut on April 5, 2006

Psephenus (Water Penny) Beetle Larva

4 Pictures

Dorsal view of a Psephenus (Psephenidae) (Water Penny) Beetle Larva from Fall Creek in New York

Every picture of this Psephenidae larva was taken with my old C740UZ through a microscope.

Collected November 14, 2004 from Fall Creek in New York

Added by Troutnut on April 12, 2006

Collected November 14, 2004 from Fall Creek in New York and added by Troutnut on April 12, 2006

Amphizoa Beetle Larva

5 Pictures

Dorsal view of a Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington

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).

Collected May 28, 2023 from Sears Creek in Washington

Added by Troutnut on June 10, 2023

Collected May 28, 2023 from Sears Creek in Washington and added by Troutnut on June 10, 2023

Coleoptera (Beetle) Insect Larva

6 Pictures

Collected May 28, 2023 from Sears Creek in Washington

Added by Troutnut on June 10, 2023

Collected May 28, 2023 from Sears Creek in Washington and added by Troutnut on June 10, 2023

1 Streamside Picture of Beetles:

View Fullsize

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).

Taken April 15, 2005 from the West Branch of the Delaware River in New York

Added by Troutnut on February 1, 2006

Taken April 15, 2005 from the West Branch of the Delaware River in New York and added by Troutnut on February 1, 2006

1 Underwater Picture of Beetles:

View Fullsize

In this picture: Insect Order Coleoptera (Beetle).

Taken May 12, 2007 from the West Branch of the Delaware River in New York

Added by Troutnut on June 5, 2007

Taken May 12, 2007 from the West Branch of the Delaware River in New York and added by Troutnut on June 5, 2007

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.