This Skwala nymph still has a couple months left to go before hatching, but it's still a good representative of its species, which was extremely abundant in my sample for a stonefly of this size. It's obvious why the Yakima is known for its Skwala hatch.
GONZO on Nov 8, 2006November 8th, 2006, 6:08 am EST
I hate to ask you to dig through your specimen vials, but I'm curious to know if you can give a size reference for this one. I've stared at it many times. My first impression was Brachycentrus, but that impression was based entirely on color and markings. I haven't been able to find any definitive keys to verify this id (though I may be missing something).
May 18 does seem a little on the late side for most of the common Eastern/Midwestern Brachycentrus spp. But, we do have a peak emergence of a Micrasema sp. around that time on the Brodheads. This is the reason I was wondering about the size. I also wanted to call attention to this specimen in the hope that Litobrancha, Taxon, or someone else might be able to end my puzzlement.
Troutnut on Nov 8, 2006November 8th, 2006, 7:23 am EST
Unfortunately I wasn't saving my specimens in vials back then. This was the first caddis pupa I photographed in the spring when I started this site. If I remember correctly, it was about hook size 16-18.
I'll move it to Brachycentrus for now based on your guess. The river where I collected it is in the far north of Wisconsin, which typically has timing more like the Adirondacks than PA or the Catskills or most of the famous MI water.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Just thought I'd take a moment to try to correct my lame old guess on this one. I must have had grannoms on the brain when I first looked at this! Although a green pupa with a dark back and belly is suggestive of some brachycentrids, that's about all that might excuse my first impression. I'm now convinced that this is a hydropsychid. If I have learned to read the hook plates on the 3rd abdominal segment correctly (thanks to Dave/Creno), this should probably be placed in Cheumatopsyche.