Laidback Gardener Tip of the Day

Controlling Carpenter Ants Indoors

20150206With the return of longer days, even when there is still snow outside, carpenter ants often begin to appear indoors… and that’s not a good thing! If you notice large ants wandering about indoors during the cold season, they are undoubtedly nesting in the timber frame of your home. No need to panic, though: ants are not termites and do not destroy entire buildings. so your home is not about to collapse! Usually they settle in wood that was already damp and rotting, but the problem is that, once installed, they will tunnel into the solid wood nearby to enlarge their nest and make passageways. So their presence indicates that a joist or beam your home is already in poor condition. To find the nest, leave out small cake crumbs in areas where you have seen ants, and then watch where they carry the crumbs. Sometimes you’ll find little piles of sawdust at the foot of the entrance holes. 20150206C

The best thing to do when you realize that you have an infestation of carpenter ants in the home is to call in an exterminator. He can help locate the nest site and suggest a truly effective solution. And don’t be worried about the toxic chemicals he might want to apply: there are organic treatments for ants that use fairly safe compounds and you can insist that he use them. In fact, the policy of many exterminators is to always use organic treatments.

20150206BIf you want to try to controlling the ants yourself, here’s a trick that is often effective. Slowly pour 2 tablespoons (28 ml) borax and 1/4 cup (60 ml) sugar into 1/2 cup (125 ml) hot water, stirring as you go so they dissolve and form a syrupy solution. Place small saucers (a bottle cap, for example) of the solution near the location where the ants carry the crumbs. (Keep any surplus in the fridge in a closed container for future use.) Boron (of which the natural mineral borax is composed) is slightly toxic and therefore the solution is also slightly poisonous. Not enough to kill the worker ants immediately, though… and that is important. The workers, attracted by the sweet solution, will bring droplets of it to the queen. As she is fed boron day after day, she will eventually become poisoned and die. And with no queen, the colony will be abandoned. But be patient! It can take up to 2 weeks to see results.

Note that the sugar and borax solution will also be slightly toxic to both humans and animals: don’t use it around children or pets.

Be forewarned, however, that carpenter ants are very difficult to control. This is largely because, in addition to the main nest, they often have satellite nests with no queen. In this case, the workers will feed the borax solution not to the queen, but to other workers. So you may well kill the satellite colony, but not the main one where the queen lives, with the result that your treatment will not be effective. Hence the idea of using the services of an exterminator: at least his work is guaranteed!

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

2 comments on “Controlling Carpenter Ants Indoors

  1. Pingback: Gardening Myth: Aspartame Can Control Ants – Laidback Gardener

  2. Pingback: Help! Ants are Destroying My Lawn! | Laidback Gardener

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