Unsure of which species this is. I thought it looked a lot like a plant i know as Devil's Club, which I've seen in Alaska but this is on the north shore in MN so I'm not sure.
The B. ternarius seemed rather pale in color in this area. I saw several with this coloration. Also, they seemed to lack pollen carried on their legs. Perhaps these were a freshly hatched brood. The coloration might intensify with time?