I found some small black beetles underneath rotting wood up at my mother-in-law’s place in Black Creek a couple of weeks ago and had a chance to check on whether or not they were still there. What I discovered was a large Ground Beetle that was superficially similar to the European Ground Beetles that I found at our place earlier in the month.
It became quite apparent that this beetle was different. It lacked the iridescent purple highlights and rather than having rows of dimples in the wing covers there were a series of parallel groves or lines in the elytra.
I’m not 100% sure but I’m leaning toward the Common Black Ground Beetle (Pterostichus melanarius) as a tentative identification for this beetle. It’s described as an European introduced species that is fairly common in back yards and gardens in North America.
Many of the species in Pterostichus look very similar so at this point I’m happy to just call it a generic Ground Beetle (Pterostichus sp.). I’ll do a little more research and post it on Bug Guide and see what bites. Will update this post if I get a conclusive identification of this wonderful beetle!
If you haven’t used Bug Guide to help with troublesome insect identification you should definitely check it out. Apparently this beetle is Pterostichus nigrocaeruleus. According to Tim Loh the beetle is:
A distinctive species due to the characteristics of the pronotum (constricted base with parallel sides & protuding front angles). There also should be purplish-bluish metallic sheen on the elytra, not visible in the image. West coast species, but in BC, has been reported only from Vancouver Island.
Very cool that in British Columbia it has only been reported on Vancouver Island!