I've been "playing" with all sorts of things to get rid of Carpenter Ants and I finally found a poison that will nail them. I have water oaks around my home and if you know those trees they rot from the inside out. That's a Carpenter Ants' dream home. The product is Termidor SC, or, Taurus SC; the Taurus is cheaper and that's what I used. They use the same active ingredient (Fipronil) in the same percentage. Neither are cheap! Amazon has it. You don't spray the ants or the nest, you spray where they travel which is the trunk of the tree in my case. I sprayed about a one foot wide band all around the tree trunks. In three or four days I started seeing dead and dying Carpenter Ants all over the ground; hundreds of them; Bingo. Exterminators use these products for termites. This is some bad poison so if you're a do-it-yourselfer, read ALL label precautions/instructions. You also need to treat again because eggs hatch. Maybe once every month I assume since I'm still working the situation. Good Luck!

Thank you, tj and Jean for your spot-on suggestions. I took your advice, and several certified arborists confirmed everything you said. The tree is not hazardous and leaving it be seems to be the best option. We were even advised not to try to exterminate the carpenter ants--apparently, they are happy where they are and not motivated to come into our home. An inspection of our home revealed no sign of carpenter ant infestation. I still cannot believe how out original arborist could be so wrong! Thank you both for putting me on the right track and saving me a lot of money and frustration, not to mention the loss of a good tree!

I do have experience with carpenter ants and I very much doubt that the Raid did much to resolve the problem. Carpenter ants typically have their nest outside the home and not in your house. They use the outside nest as a base of operations, and stream into the house like a little convoy, eat the soft parts of the wood in your house, and then leave to take this material back to the nest. To eradicate them you need to clear all vegetation that is touching your house and then spray the foundation all the way around with a specialty pesticide that will kill them when they track through it and bring it back to the nest. It's also wise to do at least one more application several weeks after the first one, or if there is a chance the rain was gotten to the pesticide. If you are not informed about the right protective gear to wear when applying the pesticide, get a professional to do this. In my case, I had three separate occurrences of this problem over a number of years at my previous house. Once you get your carpenter ant problem resolved, you will need to stay alert in future years for signs of their return, and to always keep the landscaping -- plants, bushes, and trees -- pruned back so none of it is touching the house and providing a pathway in and out.

You've seen the actual ants among that dark granular material or it is instead part of the remains of the plant structure, which you are mistaking for evidence of a nest? Carpenter ants nest in wood, if you are tearing into a nest eggs and larvae should become visible at some point. Otherwise scattered ants are foraging and not indicating the exact location of a nest. Except for when they come into a house while doing this and get onto counters etc. this behavior is of little comparative importance - the most significant thing about them being found near a wooden structure is that they might be nesting in it, gnawing out the wood. And killing a percentage of the foraging ants is not going to eliminate the nest they are coming from, which will continue to generate more ants. Ants make trails that they follow, if you are in fact seeing a number of carpenter ants moving around there look for them traveling along such routes and follow those back to the nest. They don't eat wood so the presence of their nests is marked by dust-like sawdust that they have generated and disposed of outside the entrance. If they are infesting dried conifer wood such as might be used in buildings this material will often be yellowish or otherwise pale.