There are a few things that owners of old houses are warned about from the start. Things like wood rot, windows that stick when it rains (and sometimes are simply painted shut), termites that love to eat all that old wood, and the settling of the house that makes some floors uneven enough to be trip hazards. But for all the old houses I have ever lived in, nobody ever warned me about the toughest scourge to eliminate: Carpenter ants.
When they are in their natural habitat -- out in the forest -- carpenter ants are actually very helpful. They set up shop in decayed and dead trees, where they burrow away and create huge nests. They do such a good job of it that they speed up decomposition, which is great for the chain of life in the forest. But sometimes that forest wood won't do, and they set up satellite colonies. These colonies might find the luscious, damp wood of an old house and decide that it's the perfect spot to wreck havoc.
How to find their humble abode
Carpenter ants are sly little things. When they appear in your house, that doesn't mean that you have an infestation. It does mean that they are close. Carpenter ants typically show up in your home because they are searching for food and water. They might be in a dying tree just outside your door or across the yard at the old shed. They might even be underneath that soft spot on your porch steps, where wood rot is taking hold. The tricky part is finding where they have set up their satellite colony.
This will take some midnight detective work -- literally. Stalk them in the middle of the night, using a flashlight to spot the shiny black bodies. Then follow them to wherever they might lead you. This takes some serious time and patience (and maybe some courage, if you live out in the woods like we do).
Sometimes you might get lucky and see exactly where they are going. Unfortunately, for most homeowners it isn't that simple. Now is the time to get up underneath the house and take a look at things. Remember that since the carpenter ants don't actually eat the wood, they will leave plenty of shavings on the ground near the nest. They don't actually create homes out of the wood, but use it as a way to get into hollow spaces in the house, such as the walls. That's where they set up shop.
Another interesting (and slightly creepy) way to discover them is by using a stethoscope. Don't have one? An inverted drinking glass might do. When you press the stethoscope against the wall and listen, you just might hear the busy rustling of those carpenter ants working away on their nest.
Once you've found them…
Now it's time to get medieval, so far as the ant is concerned.
It is important to avoid serious chemicals if you can. That's especially true if you have animals or pets on your property, small children running around, or a love of the environment. Besides that, these critters are smart -- they often ignore baits completely, sauntering right around the tempting goo without a second glance.
The best way to get rid of the ants is to blow natural chemicals into their nests. A few good options are boric acid, silica aerogel, or diatomaceous earth. If you can find the nest, you can drill holes into the area and blow the treatment directly into the nest with the use of a small pump or sprayer. It is also important to eliminate the problem that allowed them to get into the house in the first place.
It often takes many applications to get control of your house back, as carpenter ants are tenacious. And besides, they often have a parent colony somewhere nearby, where they get an endless supply of fresh ants heading for the satellite colony you are trying to destroy. If you can find that parent colony, get rid of it too. But these colonies can be huge, so you might have to call in a professional contractor to help eradicate it.
Finally, make sure to prevent another infestation. Keep all firewood dry, off the ground and away from your house, bringing in only what you need when you actually need it. Replace any decaying wood and keep a close eye on the things that might cause a problem, such as clogged gutters or leaks. Seal up any holes around pipes that might be an entryway, and place a moisture barrier in your crawlspaces to help deter them even further.
Carpenter ants love your home just as much as you do, and they want to stay there forever. Taking your house back requires detective work, some chemical savvy, and patience -- but in the end, you can win.