I live in the middle of the woods...I moved into the critter's territory. I seem to constantly fight damned carpeter ants. I had some white pine logs about 100' from the house, left over from my building the house. The ants had made a huge nest inside the log. Once I found them, I experiemted with them for a couple of weeks.
Every product I bought DID NOT WORK! The baits.....I put many baits under the logs and looked every day. The bait slowly disappeared...the ants did not. The boarx powder: I put powder...a lot of powder...under the logs and on the logs....they were white. The ground was white. And then over the next couple of days, there was a small pile of dead ants...as if they piled their dead. But the vast majority just kept on working. Funny to see many white ants walking all around! The SpectraCide sprays, you know, kills on contact! Did not kill on contact...though they didn't like it.
One day I drove to PA (I'm in NY) to buy the stuff you can't buy in NY. Sprayed some ants...and they just kept going...though they seemed to move faster and wiggle for awhile, as if they are being burnt. But then after a minute, they seemed to move on. But I was spray happy and I had sprayed a lot, about 2 gallons worth! The next morning I went out and looked and they were going nuts....then I noticed they were all across the yard, about 100 square feet or so, actively searching...towards the house. So, the final battle had begun. I took the chainsaw out and cut into the log. I wish I had the picture here to post. They had a true honeycomb structure about 2' long in the log. Packed filed with huge larvae. I then sprayed, literally poured the spray non-diluted on the honeycomb....they kept going. So, since this HAD to end, I got a little gasoline. Dumped it down the honeycomb (I had turn the log section upright), and BAM....instant death. No fire, just the gas. I likely used one or two cups....about 50 cents tops. Dead.
Then I sprayed another gallon or two of the juice across the yard where they were....and they all appeared to die within a couple of hours. You could stand there and literally watch them squirming/dancing from the stuff.
So perhaps the spray works....eventually...and in huge quantities.
If you know where they are coming from, if I were you, I'd make SURE to kill that nest. They swarm out looking....they have winged ants every now and then that fly off...wicked buggers. If you have to drop the tree, drop it. If you can somehow gas them in place and save the tree (is that possible?), try it. Given that they are clearly in your structure, I wouldn't mess around with insecticides....I'd use gas. No match. Just gas.
Ever since I removed that nest, we see MUCH FEWER in the house (over 100' away). I never did see a trail...so many hours looking afterdark on warm nights. Sometimes I still think I must have a colony in the house somewhere. I removed sections of drywall looking. I drilled holes and sprayed...NEVER found any sign of them.
When I built the house, I filled a corner with extruded polystyrene when framing becuase I wasn't going to be able to get back in their with fiberglass. Within a year, I had carpenter ants living in the polystyrene. In that, I did drill a bunch of 0.5" holes and sprayed gallons of the insectide....I actually redrilled back in their last fall looking...nothing. Damned buggers to find.....
Don't mess around....and don't delay. I sometimes wonder if they are destroying a truss. No leaks, new contruction, no wetness....which is what they like....so where are they? Damned if I know. And soon I will be covering the house with pine or cedar siding. I really want to make sure they are gone!
Good luck!
