I saw this thread in passing last week and then guess what I found in my brand new front and back porches this weekend? I never heard of carpenter bees until I moved to Virginia.
I tried the wood putty plug and they either knocked it out or it fell out. Normally, I am afraid of bees, but I was so mad that they were eating my brand new remodeled house that I was ready to grab one and strangle it with my bare hands!
I'm going to try Bondo this weekend to plug the holes.
All done,my FRiend...all done! Thanks for asking.
A couple of doses of Ortho Home Defense applied to the boreholes and...there ya go. Worked like a charm! I applied it before sundown,soaking the holes really good with it. Went out the next evening after work and soaked them again.
I had about 6 holes up under the eaves and I emptied those out pretty quick,and haven’t seen hide nor hair of ‘em. I did,however,find one dead one on my front stoop,and just kicked him out into the driveway. HAAAAH! Mess with the bull,you get the horns! LOLOL
Good luck with your solution,but I swear that Ortho really worked good,and I get those little buggers every single year. I sure know what to do next spring...