Carpenter bee holes should be dusted with DRIONE DUST. Use a HAND DUSTER to make the treatment. 3-5 puffs will be enough to kill the active bees. Leave treated holes open for 1-2 days and then seal them with a 1/2″ CORK.
To stop new holes from being drilled, spray CYPERMETHRIN on fencing, soffits, overhangs and other locations carpenter bees have targeted. Use a good PUMP SPRAYER to apply the cypermethrin and retreat monthly during their active season.