The way I tell the difference is bumble = hairy butt and carpenter = smooth/shiny butt (technically called "hairless"). I had always thought it was "butt" & not "abdomen", but thanks to Google, I found how wrong I was terminology wise, LOL. I always thought the abdomen was the center of the bee, not the bottom part. From the attached link: General Bumble Bee Information The "Bumble Bee" is a big, hairy, black and yellow bee whose size can range from 3/4 inch to 1 1/2 inch. This insect is often mistaken for a carpenter bee, which closely resembles the bumble bee in appearance. Carpenter bees have a shiny and smooth abdomen as opposed to the fuzzy abdomen seen on a bumble bee. The pic posted by terrene is a carpenter bee. Here is a link that might be useful: Bumble Bee Biology

Oh dear...hope everybody is fine. Queen bumbles love insulation to start a family. I would move it when dark and bumble is home,.......yes slow...but not guarantee for success.

Bumble bees are harmless, I would leave them until the babies are hatched, they don't have large colonies, perhaps 20 or so......enjoy them! Konrad

when you see the bees, look and see if they have a shiny black bottom, if they are fuzzy you have bumble bees, if they have black shiny bottoms, then they are wood bees or Carpenter Bees as Randy said. Carpenter Bees are harmless to people and pets, but they can sting if they have too, if you dont' have treated wood, they bore holes into the wood to make nests.. in time they can rot out boards around the home if they are let run crazy over years and years. DH's in-laws had the bees for 10+ years.. never had one sting us.. but they never had there home treated for it either, which rotted out boards in years to come. They are not bad bees, and they also really good pollinators to trees and our flowers. My Father in law, use to play ping-pong with the bees LOL both of DH's parents are now passed on. but I still get a giggle out of thinking about him playing ping-pong with the Carpenter bees!!