Control moisture along the foundation to prevent home-invading ants

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January 27, 2025

Dr. Jamel Sandidge, BCE

Dr. Jamel Sandidge, BCE

Nisus

The key to controlling nuisance home-invading ants is to control moisture along the foundation of a structure and its adjacent areas. Some moisture sources are obvious, like downspouts that are missing or diverting water toward the foundation. However, other sources may be less evident when you are only present for a short time at a site, such as wet leaves packed into a corner, blocked gutters that overflow, slow-leaking faucets, and thatch or compacted mulch that retains moisture.

Creating a checklist for technicians to identify and investigate often can spare you the dreaded callbacks. Many items on the checklist should address issues that can interfere with treatment efforts, wash away pesticides, or prevent control products from reaching the correct areas. Common landscape items also can protect colonies from control efforts.

Remember, only 10 percent to 15 percent of a typical ant colony forages, so locating potential nest sites and hidden protected areas will still prove crucial. Start early in the season to reduce potential nest sites by applying long-lasting dust in cracks and crevices; baiting accounts with a liquid or granular ant bait pre-emergence; reducing conducive conditions; and providing clients with helpful hints to reduce ant activity around the structure.

Check for the following and correct issues if you can or address your findings with the homeowners, if necessary:

  • Leaking faucets
  • Leaking air-conditioning (AC) compressor lines or standing water in the AC drain
  • Potted plants, which are a great spot for colonies to relocate in rainy seasons and often moved indoors in the fall
  • Blocked, overflowing or incorrectly flowing gutters
  • Brick weep holes, as there is often moisture behind the brick
  • Landscape stones, timbers, wood or statuary
  • Compacted leaves, mulch or thatch
  • Overwatered plants
  • Sprinklers directed at the foundation
  • Poor drainage areas

About the Author

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Dr. Jamel Sandidge, BCE, is national director of technical services at Nisus Corp.

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