Preventing, Coping With Carpenter Ants in Your Home

Energy Focus: Fairbanks Daily News-Miner July 16th, 2009, Section A3

Termites have yet to appear in Alaska, but carpenter ants can be rampant. Carpenter ants can destroy wood, which is found throughout a home, but are most pernicious in frame members, subfloors, and foundation areas where the ants’ boring activity is hidden from view and nests are located.

Unlike termites, carpenter ants do not feed on wood, but rather tunnel into it in order to make their nests. Over time, this tunneling can weaken wood to the point of collapse. Carpenter ants also target rigid foam insulation for tunneling. This destructive activity, plus their unpleasant presence make these ants a formidable Alaskan pest. Fortunately, colonies develop slowly and damage to wood or foam occurs more slowly than damage inflicted by termites in the Lower 48.

The first step in recognizing a problem is identifying the ants. Adult carpenter ants in Alaska tend to be black in color (though can be other colors), have smooth rounded thoraxes (the middle part between the head and the abdomen), are wingless, and range in size from ¼ inch up to 1 inch long. The carpenter ants you are likely to see are worker ants that travel in established paths to and from their nests or satellite nests. Although adult carpenter ants are wingless, young ants in reproductive mode have wings, appear in spring, and are called “swarmers.” The presence of swarmers suggests a mature, well-established nest nearby, which is sending out female ants to start a new nest.

Any consistent sighting of ants in your home should be dealt with. Other clues of an infestation include small accumulations of saw dust near wall cracks or falling from ceiling areas, sounds of crunching in your walls, or seeing ants indoors when the ground outside is frozen. Normal ant activity begins in spring and goes dormant as the weather becomes cold in the fall.

In short, if you notice carpenter ants directed toward or in your home, you have cause for concern. Most commonly, these ants will be traveling from a parent nest elsewhere in order to establish satellite nests indoors, especially where wood and moisture are present together in a house. One way of locating a nest is to follow ants that are carrying food back to their nest. Carpenter ants will feed on dead insects outside, but also consume food waste and sweets.

Unfortunately, locating and eradicating nests can be difficult or seemingly impossible. Indoors, these nests can be well hidden, hard to reach, and not easily traced. Ants may travel in winding and obscure paths. These paths become more spread out the farther from the nest they travel. Outdoors, nests can be buried underground, found in tree stumps, or tree sections.

If nests are found inside your home, they are best treated directly by a licensed pest control service. Options available include incubating an entire house to 120 degrees Fahrenheit for large infestations, targeted vacuuming, electric pulse treatment for limited areas, and approved pesticides that work best when applied directly to nests. If possible, locating a parent nest outdoors and destroying it will have a lethal domino effect on associated nests and is the best strategy.

Minimizing the use of toxic pesticides is critical – pesticides can poison water supplies, affect vegetation and wildlife, and remain dangerous in residual form for years. Pesticides can also trigger allergies or illnesses in humans.

Boric acid, diatomaceous earth, or other desiccating powders dusted in places where ants travel or congregate have the advantage of being less toxic than a poison like pyrethrin, for example, but might be less effective and not show results for weeks depending upon the degree to which nests are affected. Powders can also become diluted over time by wind and rain. If strong pesticides are required, it is best to call professionals. Otherwise, carefully read and follow the label instructions, use as little as possible in low concentrations, and dispose of any remnant responsibly.

Given the dangers of pesticides and the difficulty of finding nests, prevention is important. Begin by ensuring that your home, its walls, and its foundation are free of excess moisture, which can impregnate wood and make it more attractive to carpenter ants. Excess moisture can be caused by leaky pipes, inadequate roofing or flashing, or lack of adequate indoor ventilation. Wet wood should be removed and replaced and the cause of the moisture resolved.

In general, wood foundations, siding, decking, and stairs should not make direct contact with the ground. Treated wood will not necessarily stop ants from migrating into your home. Seal masonry cracks and other entryways into your home’s foundation and walls. Use metal flashing where practical. Remove wood scrap, firewood, and old tree stumps from around your house. Finally, consider scheduling an inspection of your house for infestation if suspect a problem.

Energy Focus articles promote home awareness for the Cooperative Extension Service (CES) and the Cold Climate Housing Research Center (CCHRC). For questions or comments please contact CCHRC at (907) 457-3454

One comment

  1. Hello,

    I am moving from a house that has had carpenter ants for four years. The landlord would never do anything so we just tried to get rid of them ourself – unsuccessfully – I might add.

    We are moving in one week. It’s Spring and the ants are back and I’m concerned we will be at risk of bringing them with us to our new home. Is there any truth to that?

    Please inform,
    I’m worried and fed up with a dead beat landlord.


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