Carpenter Ant Control

What is the best treatment for carpenter ants? Good question.

The truth is that there is no single treatment that is "best" for all carpenter ant infestations. Determining the best treatment for a particular carpenter ant problem begins with answering a few basic questions:

Where are the ants actually living?
Where are they feeding (and upon what)?
If the carpenter ants are actually living in the building, are there any structural problems that are contributing to the carpenter ant problem (moisture problems, tree limbs touching or overhanging the house, etc.).
How accessible is the nest area for direct treatment?

Ideally, the best treatment would be one that delivered a precise dose of just the right insecticide into just the right place; in other words, right smack in the center of the nest. Exterminators often refer to this as "hitting a home run" or "hitting the jackpot," because finding and directly treating the nest makes for both a quick job and an effective one.

Usually, however, finding the actual source of a carpenter ant infestation is more difficult, and treatment requires some guesswork. So the information on this page is necessarily general in nature.

Treating Carpenter Ants Outside your Home

In many cases, the carpenter ants that are seen inside of a house actually are living outside, such as in a tree, utility pole, or woodpile, and are only entering the house to get food. In these cases, treating the home itself usually is unnecessary.

For example, if the carpenter ant nest is in a tree, utility pole, fence post, or other outdoor source, then treating the source with an insecticide labeled for carpenter ants, as well as treating the exterior of the home to provide a "barrier," usually will clear up the problem. (You also should clean up whatever food sources the ants were entering the home to feed upon).

There are dozens of insecticides labeled for carpenter ant control, which come in three main forms:

Baits, such as Terro. Baits tend to be slower-acting than other forms of carpenter ant control, but they are easy to apply and give good results, especially when the nest can't be located. The ants themselves will carry the bait back to the nest, which usually provides colony elimination.
Liquids, such as Spectracide, Grant's Termite and Carpenter Ant Killer, and Scott's Termite and Carpenter Ant Killer. These products can be applied around homes to prevent carpenter ants from getting inside, or they can be sprayed directly into nests if you know where the nest is and have access to it (for example, in a hollow tree).
Dusts. There are many dust-type insecticides that can be injected directly into wall voids, roof soffits, hollow trees, and other void areas where carpenter ants nest. Dusts are very effective, but are more difficult to apply without proper equipment. Always use an approved pesticide respirator, as dusts are highly irritating and may be toxic if inhaled.

Treating Carpenter Ants Inside your Home

Carpenter ants nesting inside a building almost always mean that there is a moisture problem. In some cases, addressing the moisture problem and vacuuming up the ants will be all that is necessary to clear up the infestation.

If you can see where the ants are traveling, then consider using a liquid or granular ant bait. Placing carpenter ant baits directly along the ants' travel paths, as close as possible to the nest (for example, at the spot right where you see them disappearing into a wall), is often effective at controlling inaccessible carpenter ant infestations inside homes.

Professional exterminators often attempt to track down the exact location of a carpenter ant nest (usually in a wall void or other structural void), drill a hole into it, and puff a few puffs of a dust insecticide like Drione or Delta Dust into the void through the hole to wipe out the whole colony en masse. In addition, many exterminators routinely drill and dust void areas around kitchen and bathroom pipe chases because these are common hot spots for carpenter ants.

Drilling and dusting can be hazardous. Insecticide dusts can travel great distances inside a wall void, and unless the person applying the dust is an expert, the dust can penetrate to heating and cooling ducts and be circulated throughout the home. So if you need further interior treatment beyond that which can be accomplished using carpenter ant baits, we advise you to call a professional pest control operator. If you do decide to do it yourself, use extreme caution and follow all label instructions.