Carpenter Ant Control

Eric Ronning

Identification

There are 9 Camponotus species common in the U.S. ranging from ½ of an inch to 1 inch in length. They have a pinched waist, an evenly rounded thorax, elbowed antennae, and if wings are present, there are two sets, with the rear set being noticeably shorter than the front. Carpenter ants come in many colors including black, reddish brown, and yellowish.

Winged Carpenter Ant

Typical Carpenter Ant

Carpenter Ant in Nest

Aphid Farming

Carpenter ant pests don't usually cause serious harm, but the potential is certainly there. Given time, carpenter ant damage can be quite severe and the repairs costly. Carpenter ants prefer soft, damp wood (it's easier to excavate and provides moisture for eggs), but they will also nest in good, dry wood. Colonies can grow to 100,000 ants. When numbers get that high, a carpenter ant infestation becomes quite a difficult ordeal. When the original (or parent) colony gets too large for available resources, part of that colony breaks off to create a satellite colony, which can, in turn, create more satellite colonies. If you plan to properly control carpenter ants, you must find every colony. See the last section of this article for tips on doing just that.

Controlling Carpenter Ants

Put a little more effort into keeping the joint clean. Carpenter ant pests in the home eat a number of things including sweets, grain products, grease, and protein-rich foods (not wood). Keep the dishes washed, the counters and tables clean, and the floors swept, mopped, and vacuumed. Besides the fact that this will make it less likely for carpenter ants to stick around if they enter your home, it will make them hungrier and more likely to take the ant baits that I will mention later.

Remove potential nesting sites. When figuring out how to get rid of carpenter ants, it's always a good idea to get rid of the places where they might like to live and breed. In doing so, not only will you have the opportunity to remove real estate for potential satellite or parent colonies, you might also be able to remove existing carpenter ant colonies. Remove stumps, wood and brush piles, old logs, dead and/or hollow tree limbs, and any other extraneous wood (either naturally occurring or man made).

Control carpenter ants by controlling moisture. The key to getting rid of carpenter ants is to get rid of the parent colony. Parent colonies are found where there's moisture. The eggs, found only in the parent colony, require moisture to survive and hatch. Remove it, and the colony can't survive. Start by inspecting all pipes for leaks and condensation. Check the roof and walls for leaks. Clean and fix gutters and downspouts. Make sure attics and crawlspaces are properly ventilated and that the vents are fitted with bug screens. Finally, reduce lawn watering by only doing it when absolutely necessary. When you do water, use infrequent, deep waterings instead of frequent, light waterings, and make sure the spray is not hitting your house, garage, or any other woody things.

Exterminate carpenter ants with carpenter ant baits. These come in a number of formulations including gels, powders, and granules. Baits are great for killing carpenter ants because they can be taken by the ants to far away or high up nests. Since ants can sometimes be picky and won't always accept a certain bait, it's a good idea to purchase a few different types and figure out what they're taking. For a good carpenter ant gel, get Max Force Carpenter Ant Bait or Advion Ant Bait Gel. For powder baits, get Advance Carpenter Ant Bait. For granule carpenter ant bait, which is good for outdoor applications as it can be spread over large areas, look for Max Force Granular Ant Bait or Advance 375A Select Granular Ant Bait.

Kill carpenter ants with a carpenter ant spray. Because carpenter ant colonies can be so huge and their range so wide, sprays can be a very effective means of controlling carpenter ants. Besides the fact that many of them will kill on contact, most of them also have long-lasting, residual, knockdown power. Use carpenter ant sprays on and around structures for perimeter control and directly on carpenter ant nests and trails. Look for brands such as Dursban, Knox Out, Termidor SC, Phantom Termiticide/Insecticide, or Demon WP.

Avoid future carpenter ant infestations. Start by clearing all vegetation away from buildings. This includes bushes, trees, flowers, grasses, and anything else that might provide shelter. Next, go around your house with a caulking gun and start filling holes. Look around wires, lights, outlets, doors, windows, pipes, and spigots. When you're done outside, head to the basement or crawlspace and do the same. Some holes that weren't visible from the outside will be from the inside. Once all the holes are filled, go back outside and set up a barrier of white rocks around your house. They stay bright and dry and are a good carpenter ant deterrent. Finally, make sure there's no wood-to-ground contact. Anywhere.

Locating All Carpenter Ant Colonies

Important note: Before beginning with any type of carpenter ant control, it's important to locate the parent colony, as well as all satellite colonies. Below are several tips for doing just that.

During the day, look for piles of excavated sawdust, called frass, created by carpenter ants. Look for these below walls, cabinets, hollow doors, joists, fascia, overhangs, rafters, and window sills, as well as along chimneys and in attics and crawlspaces. In the yard, look under trees, stumps, logs, decks, outer walls, wood piles, and anything else made of wood.
Carpenter ants will also build galleries in stacks of cardboard, fiberglass insulation, and foam insulation. If you have any of these products anywhere in your home, inspect those areas, too.
Carpenter ants are primarily nocturnal. Look for active trails at night between 10:00 p.m. and 1:00 a.m. When trails are found, attempt to follow the ants back to their nests. This task may be easier if you place a shallow dish of honey mixed with cut up insect bits next to trails. This will ensure that you have an adequate number of ants to follow.
If ants disappear into your home but you haven't seen any frass build-up, there's a good chance they are in a wall void. To locate the colonies' headquarters, press your ear against the walls and listen. Carpenter ant colonies emit an audible crunching/scratching noise. If you have access to one, a stethoscope can be quite helpful for this endeavor. Plus, once the colonies are located, you may be able to talk your significant other into playing doctor.

Control Options

Use boric acid. This is my #1 recommendation for controlling carpenter ants. It's a dust made from the mineral borate. It can kill carpenter ants by acting both as a desiccant and as a stomach poison. Use it as a desiccating dust in the same way as you would diatomaceous earth (see below) or as a bait. Since boric acid is a slow-acting stomach poison, it allows ants ample time to carry baits made with it back to the nest. To make your own homemade carpenter ant bait, mix three tablespoons of boric acid with a half cup of sugar and a whole cup of warm water. Put it in shallow dishes (like plastic sour cream lids) and place them near nests and along trails.

Kill carpenter ants with diatomaceous earth. DE is the ground-up, fossilized remains of sharp-edged, microscopic ocean critters called diatoms. When carpenter ants walk through the stuff, they get little cuts all over their bodies, dry out, and die. Scatter DE at the base of ant nests, along ant trails, around the perimeter of your house, around trees you're trying to protect, in cracks and crevices in your home, and directly into the wall voids where ants are living. If they are in wall voids, drill several 1/8" holes through the wall and directly into the nest. Apply the DE with a bulb duster, drinking straw, or turkey baster.

Boiling water is an effective carpenter ant killer. Then again, boiling water will kill just about anything. If you have a carpenter ant colony that's in an easily-accessible, outdoor location, bring on the boiling water. This will probably take you several tries and several pots of water. I recommend putting one large pot of water on each burner to save time. Pour slowly and repeat if necessary.

Control carpenter ants by controlling aphids. Along with the seeds and insects that carpenter ants eat, they are also extremely fond of honeydew, a sticky sweet secretion produced by aphids. Carpenter ants will even go so far as to protect aphid colonies from other predators so that they will continue to have a steady supply of honeydew. If you get rid of the aphids, and thus the honeydew, carpenter ants will have less reason to stick around. Click the link at the beginning of this paragraph to learn how to control aphids.