Many hardware stores sell spray on woodpecker repellents, but the hitch is you have to be very careful what you use, because, apparently, all species of woodpecker are protected in N. America. Also, I'd imagine certain products might harm/annoy the bees as well.
You might try one of those fake owls, that can be mounted on rooftops to scare away pesky birds.

i am interested to learn how carpenter bees are begnign and helpful in your situation... i know them only to damage wood and to attract woodpeckers and other predators...

borer bees? wow, i've never heard of these. what's your region? and sam kusnetz refers to them as "carpenter bees", which i haven't heard of either. i thought bees were all about honey.

i'm off to do some searching.....

Quote Wikipedia:

"Carpenter bees (the genus Xylocopa in the subfamily Xylocopinae) are large, hairy bees distributed worldwide. There are some 500 species of carpenter bee in 31 subgenera. Their name comes from the fact that nearly all species except those in the subgenus Proxylocopa, which nest in the ground, build their nests in burrows in dead wood, bamboo, or structural timbers...A few species bore holes in wood dwellings and earn the enmity of some homeowners, though others regard them as pets. Male bees are seen hovering around the nest, and will approach nearby animals. However, the male is harmless since it does not have a stinger. Female bees do have a stinger, but are preoccupied with foraging and will only return to the nest to stockpile. Female bees are not aggressive, and will not sting unless directly provoked. Since the tunnels are near the surface, structural damage is generally minor or nonexistent...In the United States, there are two eastern species, Xylocopa virginica, and Xylocopa micans, and three other species that are primarily western in distribution. X. virginica is by far the more widely distributed species. Some are often mistaken for a bumblebee species, as they can be similar in size and coloration, though most carpenter bees have a shiny abdomen, while in bumblebees the abdomen is completely clothed with dense hair."

Reference

As far as the Woodpeckers go, I actually had the same problem. I used a product called Bird Repellent Ribbon. It is a holographic foil strip that drives unwanted birds away like woodpecker by producing an optical and audible discomfort zone. I never had any problems again.

Borer bees are indeed also called carpenter bees, because they drill perfectly round 3/8" holes. They pollinate like all bees (not much good for honey) and generally mind their own beeswax.. I discovered them after these tidy holes appeared and I poked a straw up one and tickled something. They are large and have shiny black abdomens, I discovered immediately.

Honey bees are mysteriously disappearing and leaving the agricultural community and those who notice these things extremely alarmed. So any pollinators are welcome.

Flickers, sapsuckers and other woodpeckers like the soft cedar and hear the noisy larvae of the bees. It is illegal to kill the birds but mechanical prevention may work. Probably not, as they will usually move to a more inaccessible part of house, as will bees. In my rural community w. acres of woodland, there are more smart birds than I would have thought.

I even saw a male fox recently during the day, loping around. (He probably was rabid.) And one can hear the coyotes and large owls at night, picking off small prey, very noisily, I might add.

I have wood bore bees in a wooden shed in my back yard. The shed is pretty old (14+ yrs) and I am trying to replace it. We thought cedar might discourage the bees, but I’m hearing that they love cedar. Any suggestions about what kind of wood to use? By the way, the holes in the shed don’t seem to go all the way through, and we haven’t, as yet, had any problems with wood peckers.

@Morgan: you are right about the holes. The bees bore about one inch vertically up and then make a right angle. Do you have property with lots of trees that might draw a woodpecker population? My woodpeckers took several years to discover the bee larvae.

I now hang aluminum pie plates from long strings…they catch the breeze, glint and bank into garage doors. Successful? Not so far. Attractive? No,

I have seen pictures of lovely little sheds made from stone and grout, rather like a tiny Celtic Chapel. Expensive, of course, but should last as long as Stonehenge.

Gardensheds Hall of Fame

Call your local Aggie extension or School of Agriculture if you are near a large University. Or read the dozens of hits when you Google “Borer Bees.”

If you want to get rid of bees, check out this electronic insect repellent device.

For the woodpeckers, you can try an owl decoy for a small problem
or a sonic woodpecker repellent device for a more thorough solution

@birdstuff; thanks for the tips but I finally decided that we will all happily coexist.. Too many bees, too many woodpeckers and too much exterior cedar to turn the house into an armed encampment.

And I could not stand yet another gadget. Let the food chain flourish even though my cedar siding seems to be part of it.

No problem! Good luck with your birds and bees :)

I did solve the mice-in-my-car problem when my daughter lent me her cat, Milo the fabulous. Now my problem is to keep Milo from sneaking out after dark, speaking of the food chain. He would make a tasty morsel for an owl, large hawk, coyote, fox or whatever else is out there, lurking at night. The coyotes sometimes sound like a 100-person a capella choir singing in too-high a register.