My guess is that this is a female Great Black Wasp, however, the white bands on the antennae are not typical — open to correction on the ID. A couple of viewers have suggested an Ichneumon wasp, but the size and antennae make me wonder about that id. Found actively exploring back and forth on a trail bench under a mixed hardwood stand, South Central Ontario, this one was about 30mm (1.25") in length. A. single handheld image.