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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington
Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
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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Giant Water Bug Species Belostoma flumineum (Electric Light Bugs)

Where & when

In 141 records from GBIF, adults of this species have mostly been collected during September (18%), August (15%), October (15%), July (13%), May (12%), and June (11%).

In 12 records from GBIF, this species has been collected at elevations ranging from 246 to 1083 ft, with an average (median) of 620 ft.

Specimens of the Giant Water Bug Species Belostoma flumineum

2 Adults

Discussions of Belostoma flumineum

Anyone else find these to be important?
2 replies
Posted by Troutnut on Jul 26, 2006
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 Belostoma flumineum

References

Giant Water Bug Species Belostoma flumineum (Electric Light Bugs)

Taxonomy
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