We're having a bumper crop of carpenter bees this year and I think I've found a solution. 32 H&R shotshells.
I have a bunch of 22LR shot shells but that's too easy.
I was planning on loading a gas check on top of the powder and on top of the shot with a slight crimp but I simplified it a bit.
A load of 2.0 gr Titegroup and a cardboard wad punched from a cereal box over the powder. Scoop the case nearly full with #12 shot and a smear of silicone caulk over the top.

I tried 1gr of Titegroup but that was too light, 1.5 gr was better but 2.0 gr burns clean and puts down a nice round pattern at 8' from a Charter Arms 3" revolver.
86-87 gr of #12 shot per load.

These were loaded single cartridges, the next test will be to try them with another shell along side to see if they stay in tact.

Look out Carpenter bees!

It's going to be for snakes on my woods walks too.

"Camping places fix themselves in your mind as if you had spent long periods of your life in them.
You will remember a curve of your wagon track in the grass of the plain like the features of a friend."
Isak Dinesen