Patrolling the Perimeter

“The best advice for homeowners is to limit landscaping and the depth of wood mulch around the house,” adds Jackie Thornton of Alvin Pest Control in Alvin, Texas. “The trend of having deep-mulched beds and lush landscaping right up next to the home is an invitation for sweet-feeding ants to come in close and, ultimately, come into the house. The mulch creates substrates that are ideal nesting areas, while nectar- and honeydew-producing plants provide a plentiful food source.” 

 

While the above practices are appropriate for preventing most ants, treating infestations requires a closer examination of the type of ants involved. Identifying the species will help you locate the nests, entry points and signs of infestation. For example, pavement ants nest in soil, and workers often enter homes through expansion joints or cracks in a slab. Wood-destroying carpenter ants tend to nest inside the house (although the parent nest may be located in a tree or stump outside), while odorous house ants are more likely to nest outdoors, going inside primarily to forage. 

 

“This is the time when we need to become detectives,” says Mastrolia. “We start by asking the homeowner questions about ant activity. The customer generally doesn’t know a Pharaoh from a ghost ant, or an Argentine from a carpenter ant. It’s our job to take the information they provide along with the clues we collect from our inspection and identify the species, locate the colony and create a treatment program that works with the biology of the pest.”

 

Most PMPs report that perimeter pesticide applications are effective, whether used as a preventive protocol early in the season or once an infestation has occurred. Nonrepellant formulas, especially those with delayed action, are popular because they allow the ants to carry the insecticide back to the nest and distribute it throughout the colony. Repellants can cut indoor ants off from their outdoor colonies, causing increased indoor activity as they look for an escape route, to the frustration of the homeowner.

 

“Nonrepellant products are much more effective in eliminating colonies than repellants, which often simply move the ants to a different location,” says Jeremy Kreer of Advanced Pest Management in Elkton, Md. “Our perimeter treatments include treating the foundation, mulch beds, ant trails and siding voids with baits, dusts, granular insecticides and liquid residuals. We find that nonrepellant residual products are particularly helpful in situations where the nest is difficult to locate.”

 

In situations where the nest has been located, direct treatments of residual insecticides are effective. These guidelines can help you determine which formulation to use:

 

 

Most PMPs treating ants inside the house also use baiting. The bait formulation and matrix most appropriate for your situation depends on the species of ant you’re treating, along with its food preference. (Also read “Let Them Eat Baits!”)

 

Some PMPs maintain, however, that if you treat the perimeter correctly, you have the problem beat. Wescott, for example, says that 99 percent of Inspect-All’s ant program focuses on the exterior of the house. “In cases where ants have set up shop inside, we’re still looking for the external entry point,” he says. “Eliminate the source outside and the inside will take care of itself.”