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Photo#498741
Alderfly? - Sialis nevadensis

Alderfly? - Sialis nevadensis
Tahoe National Forest, Placer County, California, USA
July 2, 2010
Size: ~2cm

Moved
Moved from Sialis.

Moved
Moved from ID Request.

yes, but those colors!?!?
stunning.

 
Yep, stunning!
Maybe just a colorful Sialis nevadensis? That's just a guess. The colors don't seem to fit any of the other Calfornia species, but I haven't really studied Sialis that closely. I'll look through my collection to see if I have any of that species. I don't recall ever seeing one that looked like this, but maybe I overlooked a specimen.

Ross (1937) gives this for S. nevadensis males: "Black with the following exceptions: head usually with an orange band covering lateral area of head and posterior half of vertex...." and for the female, "color and general structure as in male, except that the head is usually shining and impunctate."

Ross, H. H. 1937. Studies of Nearctic Aquatic Insects I. Nearctic alder flies of the genus Sialis (Megaloptera, Sialidae). Illinois Natural History Survey Bulletin 21(3):57-77.

 
Thank you both...
I was quite shocked, too...all the alderflies I have seen were pretty much blackish or grayish!

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