Tanya, resolve next winter(before it gets too cold to paint) to have those bore holes filled and the entire surface repainted thickly. I have the same problem on my other house, a contemporary with thick fascia boards. We're going to have them covered with the mesh wire used with stucco applications and then spray painted.

It's primarily the males who are doing the dive bombing to guard whatever section of the house they've staked their claim to. Annoying but they don't sting.
The moms can and do sting but they're busy getting food for the larvae developing in the chambers.
You could also cover the backsides of the fascia board with cement board but I think the mesh is a longer lasting solution. The mesh is too fine for them to chew into the board behind it.

Here's a bit of info on both the females and the drones pulled from a website. The female is an excellant pollinator and killing them should be avoided.

Drones - Some folks are terrified of this buzzer. You won't see him visiting flowers and minding his own business like the female. Rather he'll be looking you over to see if you are sexy. Drones have a territory that they watch, and anything within it that moves, will be investigated.
There is not an ounce of aggression in this harmless fellow's body, except toward other drones. He cannot sting you anyway. So when he comes to buzz around you, look him straight in the eye and dance with him. Toss a pebble and watch him chase it. Look cross eyed, or stick out your tongue at him. See, all he'll do is a friendly buzz game. This is an ideal chance to teach your kids one of the joys of nature, rather than load them up with wasted fear of something completely harmless.

She's often mistaken for a bumble bee, but is easily distinguished by her shiny black butt, instead of a fuzzy gold and brown butt.
Carpenter bees are much maligned because they bore into wood to make their nests, but they are valuable pollinators and should be protected. Usually the damage they do to wood is just cosmetic.
They pollinate many spring flowers, though they sometimes slit blueberry flowers and steal nectar without pollinating them.
Carpenter bees are solitary bees, with each lady making her own nest. They are most common in early spring.

There are also suggestions on the internet for providing nesting for the carpenter bees, one being basically to provide nesting blocks made out of untreated softwood such as pine or fir. A commonly sized block is 4"x4" or 4"x6", drilled with holes that are about ¼"-3/8" wide and 4-6" deep. Brian Griffin, who raises orchard mason bees in Washington, drills his 4"x6" blocks with holes on ¾" centers, so that each block has 102 holes. (9) He angles the front of the block and places a piece of cedar shingle on top, to act as a roof overhang. These blocks can be used for many years and can be cleaned with a bleach solution.

Good luck!

Heather

Someone told me to plug holes with steel wool. They have almost destroyed our playhouse.

Carla

That will work for a time but steel wool degrades(rusts into nothingnesss) and you still have lots of chewable wood.
Fortunately, soffits and fascia boards are cosmetic rather than load bearing.

I stand out on my front porch with a Tennis racket, drink a beer and serve them into the neighbors yard :)

actually, that worked at my last house....and its what my orkin man next door neighbor recommended.

And while soffits and fascia boards are mostly cosmetic, in that they don't help hold up the structure to which they are attached, they do have their uses and it's time consuming and expensive to replace them, so writing them off as negligible comes off as a little thoughtless.

If the bees really are eating your wood, then there are a couple of ways to treat them. Having the exposed wood sprayed with a powdered insecticide mixed with liquid, so the powder stays on the surface and is walked through by the bee will kill off the ones who walk on the wood. Painting the wood will deny them access, stains aren't as effective. And using a puffer bottle to squirt a little insecticide powder (pymethrin, pyrethrin, etc.) in the hole, so the bee walks through that will also kill them, as they groom themselves and ingest the powder. Knocking them down - tennis or badminton rackets work very well - and stepping on them also kills them - but they do learn that trick, and will disappear as soon as you show up, only to come back when you go around the corner! You do have to squash them, as they are only stunned by being knocked down.

If you want to preserve the bees, hanging up blocks of untreated wood, drilled with holes or not, will allow them a spot to live without them destroyng your buildings. I know of one person's place near here where the porch steps fell apart after a number of years of bees nesting there, so their drilling holes can be dangerous, as well as purely cosmetic.

I do agree that with the decline in honeybees, especially the latest threat, helping the native bees is good, but it does need to be balanced with some common sense - we are living here also, and adjustments can only go so far. To go with the line of thought that says humanity is the highest good and should "have" whatever humanity needs without thought for the rest of nature is as foolish and shortsighted as to say that Nature should be paramount and hmanity should not be here. We are here, and therefore, we should do all we can to make our impact as light as possible, but living in poverty or squalor is no more attractive to me than living in great wealth!

get a fly swatter and pop the #%$@ out of those suckers!

dibbit, my response wasn't meant to be flippant, much less thoughtless.
Since my other home suffers the same problem I've given the solution a lot of thought. Fortunately, the damage repair can be delayed because these aren't load bearing boards. This give the homeowner time to address the problem in colder weather when the c.bees are dormant.

We need all the pollinators so I don't agree with the insecticide route. In late fall , we will be tacking up tight wire mesh to the back and undersides of our problem areas before repainting.
The objective is to discourage all carpenter bees from using our home as a nesting site.