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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.

Dorsal view of a Glossosoma (Glossosomatidae) (Little Brown Short-horned Sedge) Caddisfly Larva from the Yakima River in Washington
I caught this tiny larva without a case, but it seems to key pretty clearly to to Glossosomatidae. From there, the lack of sclerites on the mesonotum points to either Glossosoma or Anagapetus. Although it's difficult to see in a 2D image from the microscope, it's pretty clear in the live 3D view that the pronotum is only excised about 1/3 of its length to accommodate the forecoxa, not 2/3, which points to Glossosoma at Couplet 5 of the Key to Genera of Glossosomatidae Larvae.
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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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

Specimens of Giant Water Bugs:

2 Adults

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

True Bug Family Belostomatidae (Giant Water Bugs)

Taxonomy
Genus in Belostomatidae
Belostoma
2
18
Genus in Belostomatidae: Belostoma
2 genera (Abedus and Lethocerus) aren't included.
Family Range
Common Names
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