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Stonefly Nymph - Epeorus pleuralis - Epeorus

Stonefly Nymph - Epeorus pleuralis - Epeorus
Alma/Fundy National Park, Albert County, New Brunswick, Canada
August 14, 2009
Size: ~8mm
This larva was captured in fast flowing clear & cold fresh water (Dickson Brook) and photographed in the water. I'm pretty sure it is some sort of Stonefly larva but that's as far as I can get. I have more shots but they all look pretty much the same.

Moved from Mayflies.


To the best of my knowledge, there are only two genera of N. American Heptageniids with only two tails in their nymphal lifestage, Epeorus and Ironides. There are records of two Epeorus species in New Brunswick, E. pleuralis and E. vitreus, and to my knowledge, no records of Ironides. I suspect your photo is more likely to be of E. pleuralis, largely based your description of the stream in which it was found, as they tend to favor cold fast-moving streams, whereas E. vitreus tends to favor slow meadow streams. However, it would be necessary to examine the posterolateral spines, the femoral flange, and the 1st gill to more confidently differentiate between the two species, and even that would probably not be fail-safe.

Should have been spelled Ironodes. It has a single species in N. America, I. nitidus.

Greatly appreciated!
Hello Mr. Rohrbeck

Thank you for your very thorough explanation. This is exactly the sort of information that is very useful to me.

Beautiful shot Brian (as always, naturally)! If you're wandering around the edges of rivers at Fundy these days (Dickson, Upper Salmon, Point Wolfe, etc) above the head of tide, do look for very cool Winter Stoneflies right now, as they are definitely out in the yard up here in Kent County! I posted some shots from this week here.... This is perhaps THE group of insects (Stoneflies/Mayflies/Caddisflies) of greatest conservation concern in N Am these days, yet we still very little about them...For example, there is a species of stonefly known from a single individual (!!!) collected on the Pokiok Stream in the early '80s and it is called Alloperla acadiana...

Something to look for
Thanks Denis

I'll have to get out and have a look for them - when I'm not chained to my computer.

Moved from ID Request.

This is a mayfly nymph
Family Heptageniidae. Looks like it could be Epeorus, but let's wait for an expert.


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