This is probably THE biggest bee I've ever seen. I heard it well before I spotted it, it's also the loudest bee I've ever heard. overnight temps at this time was around -1 celcius, at the time I'd spotted this it was 10:50 a.m. and already almost room temp. The bee however was very slow moving between flowers which were locus (or loco) weeds. After leaving a few clusters and having to fly around 5-7 feet, it did speed up, however I could easily get my camera close down to it. This is about as late as you'll find bees around here in Canada, however these were at the bottom of a badlands area on a windless unusually warm day.