Carpenter bees look very close to bumble bees, but they have a lot more black color than you would expect to see. They are solitary and don’t nest like a wasp. However, they can set up individual nests in the same area. When a carpenter bee finds a place it likes ( bare wood ), it will bore an almost perfect circular hole into the wood and then turn 90 degrees and tunnel with the grain. It will lay several eggs, separating each with wood pulp. These eggs will hatch and move out to find a place to set up their own set of eggs. Later in the season, as they look for a place to overwinter, they may come back to the hole they were born in since the “mother” leaves a pheromone around the opening for recognition later. This is why you can see multiple carpenter bees in one area season after season, like the picture above. The best service approach is to treat locally, and then a follow up later in the season and finally closing up the hole they made before freezing weather sets in.