Bees often go inside of attics or parapet walls at the roof because of the elevated location and protection against predators.
Large bees under roof.
You wont be able to see the hive or swarm on the inside but you will notice flight activity going in and out of the vent hole.
Carpenter bees are solitary bees and they have very different nesting habits when you compare them to other varieties.
In my yard i have both flowers and hummingbirds who also pollinate.
The hole will appear perfectly round and perhaps half an inch across.
The bees are attracted to it and once in the solution they are doomed.
I use a solution of super thick water and sugar in a large tub each day to rid my yard of them.
It s too sticky to escape.
If you see large black and yellow bees which hover around and dart in and out of the eaves around your home then you stand a good chance of having carpenter bees in your roof.
Common places for bees to hide and build nests include overhangs cracks window frames shutters door frames and underneath the siding.
When you see several large bees hovering around in the same place every day there is probably a nest somewhere nearby.
The screen on the holes are usually 1 4 inch which give the bees plenty of room to squeeze through.
Once they get in the attic they will usually build a hive on the under side of the roof.
They prefer being inside as opposed to being outside nonetheless bees can build on the outside but its not near as common.
In the picture below these bees have protection from the rain sun.