I had carpenter ants in my house 10 years ago. Black ants...some big and some small. Terminex was called but that guy did very little and just sprayed. Next year he did the same and we still had ants. I took the day off to work with the guy and hope he would find the nest. He was very lazy and I terminated the contract. A few months later I was outside on the front yard playing catch with my son. It was a warm, humid, early evening and they sky was overcast (all white clouds). Believe me, this is leading to good info...
So, I happened to look up while playing catch with my son and what did I see? I saw an image going across my telephone wire to the house. I walked closer and saw it was moving. I got the extension ladder out and climbed up the side of the house and to my amazement I saw a carpenter ant coming right to the house, onto the siding and around the siding and out of sight. I look down the phone wire back to the pole and I saw probably 10 more ants marching my way. I shook the wire violantly and knocked them all off. I stood up there on the ladder for about a minute and low and behold more ants coming my way!!
That night I sat and htought about what to do???? I could spray, but the ants will walk right over the spray. Besides, how much spraying can you do on the phone wire? I thought about fabricating something to deter the ants from getting onto my house. I had nothing. Then went on-line and looked for ant baits. Bingo! I bought a bait made by MaxForce over the internet. It's called MaxForce Carptenter Ant Bait Gel. A gel! That's what I needed to put on the telephone wire and it would stick.
About a week later the bait comes in the mail and up on the wire I went. I squirted some of the clear gel onto the wire. It has the consistency of vaseline and just globs onto anything. You could apply the bait upside down and it would still hold.
Long story short, I applied this bait for like 5-7 consecutive nights and reapplied if it rained earlier that day. Low and behold, within I would say a month, we no longer had ants in the house in the rooms we always saw them. And the proof is no more ants coming across on the telephone wire. It's been over 6 years now and not one carpenter ant in the house!
So, my advice to you is twofold. First, get a tree expert over to your home to inspect that tree. They will be able to determine how extensive the damage to your tree might be. Believe it or not, those little buggers can eat away the inside of your tree like there's no tomorrow and when a decent wind storm comes, your tree will fall. I split a lot of firewood and see a lot of trees taken down and it is amazing how those ants can hollow out the inside of a tree where you only really have solid wood on the outside 2 inches of the tree while the middle is hollow or very soft. Second, get MaxForce Carpenter Ant Bait Gel and put some of that down, like if you have a lot of ants, put down enough as if you were putting toothpaste on your toothbrush. Watch the ants eat it and they take it back to share with the colony. You will kill most or maybe all of the colony.
If you are lucky, and if you can locate the actual nest in the tree, then buy some highly potent chemical stuff and kill them all. The key is to locate the nest and kill the queen and all the others!
PM me if you have any questions. I am not an exterminator...I have just a very good background in home maintenance.