A male. Thanks for the interesting description of his unusual behavior. These guys are very territorial and normally would beat up on a bumblebee. Since it was a rainy day, he might have cooled down so much he couldn't summon up any aggressive moves. But I suspect he was at the end of his last useful day, in which case his leg-lift could have been a weak aggressive display; he has hooks on the underside of his abdomen that he reportedly uses to wound other bees. The reason I suspect he was on his last legs is that, in our CT garden, the large males seem to go very suddenly from near-constant activity to total burn-out. They're there every day for two or three weeks, defending their particular patch of flowers against all comers and trying to mate with each female who lands on that patch -- then, late one afternoon, they settle on a flower and just stop. The next morning they're gone, like yours.