Thanks for correcting my misidentification on this. It would be nice, and make sense, if my title were changed. Is that something I can/should do? It seems appropriate. I cruised the guide to find images of the adult beetle. Wow! I've only seen these in books or here, on my favorite website of all time. I've never seen an adult of this species, hence my assumption that it was a diurnal firefly larva. But, I wonder--is this a larva or an adult female? Absolutely fantastic resource this website is! Very grateful to you both.

Oh, and I added a few promised images of feeding behavior!

re: title; editing it is totally up to you --knock yourself out, but keep in mind you'll have to make the changes manually on every single image of the series (use cookies) :/
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it does sound puzzling that you found a larva of a beetle you've never seen in adult phase, but not of the one you see scores of... such things do happen, though, and are not that uncommon among the lampyrids and their allies w/bold, aposematic larvae (e.g.,(1))

I just reviewed all images on Bugguide for this species. Sexed specimens are all identified as male ("beetles"). Eric Eaton makes a comment that females are larviform at the following image. http://bugguide.net/node/view/40557/bgimage