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.

I caught several wild and colorful 8-9 inch brook trout in the clear little pool below this waterfall.

From Mystery Creek # 89 in New York

Stream photos

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Female Hydropsyche (Spotted Sedge) Caddisfly Adult Female Hydropsyche (Spotted Sedge) Caddisfly Adult

Lateral view of a Female Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Adult from the Columbia River in Washington

7 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.

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 Bug Family Belostomatidae (Giant Water Bugs)

Where & when

In 1049 records from GBIF, adults of this family have mostly been collected during July (12%), September (11%), August (11%), June (10%), October (10%), May (10%), April (10%), March (7%), and November (6%).

In 40 records from GBIF, this family has been collected at elevations ranging from 33 to 12303 ft, with an average (median) of 787 ft.

Family Range

source

Map of specific collection sites

Specimens of Giant Water Bugs:

2 Adults

Belostoma flumineum (Electric Light Bug) Giant Water Bug Adult

14 Pictures

Giant water bug. This dangerous aquatic predator belongs to the species Belostoma flumineum, in a family known as the "toebiters"

Artistic view of a Belostoma flumineum (Belostomatidae) (Electric Light Bug) Giant Water Bug Adult from the West Branch of Owego Creek in New York

I'm glad I finally got one of these Belostoma water bugs under my good camera. I had been hoping to get one in my kick-net samples for a while with no luck, but I ended up finding this one drifting midstream just below the surface while I fished. I have frequently seen water scorpions do that, too, and I'm beginning to suspect that is a common situation travel for these large Hemiptera bugs, and perhaps the way trout are used to seeing them.

Collected April 23, 2007 from the West Branch of Owego Creek in New York

Added by Troutnut on April 24, 2007

Collected April 23, 2007 from the West Branch of Owego Creek in New York and added by Troutnut on April 24, 2007

Belostoma flumineum (Electric Light Bug) Giant Water Bug Adult

4 Pictures

Lateral view of a Belostoma flumineum (Belostomatidae) (Electric Light Bug) Giant Water Bug Adult from the Namekagon River in Wisconsin

I haven't seen the imitation of these things stressed, but in August 2003 on one of my favorite rivers the largest brown trout I kept had stomachs full of these things.

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

Discussions of Belostomatidae

Anyone else find these to be important?

2 replies

Posted by Troutnut on Jul 26, 2006 in the species Belostoma flumineum

Last reply on Oct 9, 2006 by GONZO

Back when I was just starting to learn to fly fish and still kept quite a few fish, I autopsied the stomachs of a couple 17-19 inch brown trout in August and found them packed with these Belostoma flumineum bugs.

I haven't tied a reasonable imitation yet, but if those fish (from a few miles apart on the same river) were so fond of them an imitation is probably a great idea. It would be good to figure out where and when these things are important.

None of the fly fishing literatue I've seen has dealt with them at all, except for mentioning their existence in passing.

Start a Discussion of Belostomatidae