LH,

Down here in Texas there is a fellow named Howard Garrett who is "The Dirt Doctor," and specializes in organic gardening and pest control. There are a number of things that can work, but it depends on getting access to the timber they're in or their nests, if they're at an intersection of dirt/structure, etc. http://www.dirtdoctor.com/ will get you there.

This is his most current information:

Organic control: Boric acid products indoors; plant oil products, diatomaceous earth, beneficial nematodes. Acrobat ants and odorous ants are controlled with the same techniques. Almond oil works well to repel them and is especially good for treating wood.

The rest is here: Carpenter Ants page in the Dirt Doctor library.

Personally, after you find the various population centers and the queens, I would look into spraying around the house with beneficial nematodes, and spray the actual nests with the strengths he recommends of orange oil. Diatomaceous earth in a gardeners store (he has been recommending one that comes in a bottle that you can puff into cracks and crevices or over plants, etc. It treats a lot of pests) will stick around for a while. Don't get the kind that is used for pool filters. That isn't the same and it can have some toxic impurities mixed in. Good diatomaceous earth can be used in human and animal diets, and it's okay to have a little dust of it around the house in places. No harm to other living creatures like dachshunds.

Boric acid is a great treatment if new wood is going in, just soak it and they will leave it alone. As will termites. If you have to replace damaged lumber, spray the wood before it is put in, or before the wall is finished. That'll keep them away.

Good luck!

SRS