Killer bees

Actually, not killer bees, more chewing, gnawing, pesky bees. We have carpenter bees: they look like bumble bees but instead of hairy backs, they are smooth and shiny; they don't sting (often) but they like to hang out on the redwood siding and chew little holes in it. They chew a hole in, turn at right angles, tunnel down a few inches and exit through a new hole. Hooray, they don't do structural damage, boo, they leave the siding looking like swiss cheese!
We have spent the last few weekends experimenting with various insecticides in an attempt to rid ourselves of the little critters. I wouldn't bother but they make a lot of noise while chewing and this freaks me out, especially as they are by my bedroom window and they chew throughout the night. We could call in te professionals but apparently killing the buzzing ones requires time and patience and that translates to lots of money, and it is quite easy to kill them yourself. You need either powder insecticide and a baster or a spray with a long nozzle to poke into the holes. I was also told you could spray them with WD40 and that should be easy as it comes with a target nozzle but it didn't kill any bees although the ones flying around didn't squeak at all.
The powder worked well where we could get it directly into the holes,and there were a few dead bees beneath the holes the next day but some holes were too high under the eaves to reach and the gnawing continued. Then we tried a spray and had some limited success. If we got it into the hole it worked but often we couldn't be precise enough. Then the spray attachment snapped off so I drove to the hardware store to buy a spray bottle to transfer the poison. By this time I was pretty mad so I picked up three different brands of aerosol insecticide, all specifically for carpenter bees and drove home to perform a little experiment.
Brand A when sprayed directly on a bee rendered it dizzy enough to fall to the ground where I could stomp on it. Brand B seemed to have no effect on the bee except to make it shinier but Brand C had a dual use: if sprayed into the hole, it foamed up, leaving the hole covered and causing the bee inside to groan horribly; when sprayed in the direction of the bee the product caused it to instantly fall lifeless to the ground. Instant gratification and our product of choice for the future. And there will be many more opportunities to use it as they are still chewing in a couple of hard to reach places.