Off all the housewarming gifts you received, black ants probably did not make your list of most favorite. If you’ve discovered black ants have made themselves at home even before you’ve finished unpacking then chances are you have carpenter ants. Although a number of black ants make their way indoors, carpenter ants are usually the culprit in newer homes especially when these homes are built on or near wooded lots.
What are Carpenter Ants
Carpenter ants (Camponotus spp.) are one of the largest black ants in North America. They can be anywhere from 3/16 to 1/2 inch long. Their name comes from the ability to tunnel through wood. Unlike termites, they make clean tunnels that almost appear sandpapered. They do not eat the wood, but simply remove it to expand their nesting site. Although they prefer to nest in decaying wood, they move on to sound wood once they have established themselves.
Why Carpenter Ants Enter New Homes
New homes are prone to carpenter ant construction because wooded lots usually already have an established colony of carpenter ants in residence. When construction begins, this colony establishes a satellite colony inside the home. The colony maintains a trail back to its parent colony but still contains several thousand members. Colonies may also move inside a new home when disturbed, which often occurs during construction.
Signs of Carpenter Ants
The first sign of carpenter ants is the ants themselves. Carpenter ants are usually most active at night between 10 p.m. and 2 a.m. If you place a piece of sweet food out, you may notice ant activity around it during this time. You can then follow the ants back to the nest, which is probably located in the walls of your home. The nest can sometimes be found by tapping on the walls and listening for a hallow sound and ant activity. Spraying an insecticide with pyrethrins can also be used to flush ants out of an area to locate the nest.
Controlling Carpenter Ants
Once the nest is found, it should be treated by applying an insecticide. Effective insecticides for carpenter ants include boric acid, silica aerogel, bifenthrin, cyfluthrin, eltamethrin and permethrin. If the nest is inside the wall, you can apply the insecticide by drilling a small hole, about 1/4 to 3/8 inch, into the wall and inserting the insecticide through the hole. Holes can then be patched after ants are effectively treated. Treating the nests is usually more effective than using bait when dealing with carpenter ants.
Carpenter Ant Prevention
Since carpenter ant usually establish satellite colonies inside homes, it is important that you take steps to keep carpenter ants from reentering your home. This means going around and looking for any cracks that the ants may be using to get inside. Use caulk to seal around pipes and wires into your home. Prune back any vegetation that may be touching the house. Store firewood off of the ground and away from the side of your house. Burn any rotting wood rather than burying it.
- Washington State University Extension; Carpenter Ants: Their Biology and Control; Laurel D. Hansen, et al.
- The University of Maine Cooperative Extension; Carpenter Ants; James F. Dill, et al.
- PennState Entomology; Carpenter Ants; Steve Jacobs; January 2008
- University of Minnesota Extension; What To Do About Household Ants; Jeffrey Hahn, et al.
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