Pests in Gardens and Landscapes: Quick Tips

Ants

Published   3/14

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Argentine ant

Argentine ant.

Various types of bait stations are available

Various types of bait stations are available.

Fill ant entryways with caulk.

Fill ant entryways with caulk.

Although ants are annoying when they come indoors, they can be beneficial by feeding on fleas, termites, and other pests in the garden. While spraying chemicals inside the house might seem effective, it won’t prevent more ants from entering your home because most ants live outdoors. Instead, focus efforts on keeping ants from entering buildings. Combine several methods such as caulking entryways, cleaning up food sources, and baiting when necessary. Avoid using pyrethroids (e.g., bifenthrin and cypermethrin), especially on hard surfaces such as driveways or sidewalks or around the foundation of buildings. These products pollute waterways.

Make your house less attractive to ants.

  • Caulk cracks and crevices that provide entry into the house.
  • Store food attractive to ants in closed containers.
  • Clean up grease and spills.
  • Ant-proof kitchen garbage pails with sticky barriers such as petroleum jelly under the lip and place pet dishes in a moat of water.
  • Remove or manage sweet food sources next to your house such as aphid-infested bushes and ripened fruit on trees.
  • Keep plants, grass, and organic mulch at least a foot away from the foundation of buildings to reduce ant foraging and nesting.

When ants invade your house:

  • Sponge up invading ants with soapy water as soon as they enter.
  • Plug up ant entryways with caulk.
  • Take infested potted plants outdoors and submerge pots in a solution of insecticidal soap and water.
  • Clean up food sources by wiping up spills or placing food in tight-fitting containers.
  • Rely on outdoor baits to control the ant colony.
  • Insecticide sprays shouldn’t be necessary.
  • If you hire a pest control company, ask them to use baits and spot treatments rather than perimeter treatments or monthly sprays.

How baits work:

Pesticide baits work by attracting worker ants who then take the product back to the nest where the entire colony, including queens, can be killed. The pesticide must be slow acting so workers won’t be killed before they get back to the nest.

How to use baits:

Place baits near ant trails and nest openings. Prepackaged or refillable bait stations or stakes are the safest and easiest to use. Active ingredients in baits may include boric acid/borate, fipronil, avermectin, or hydramethylnon. Liquid borate (0.5-1% borate in sugar water solution) baits in refillable bait stations are best for severe Argentine ant infestations. Replace baits when empty and reposition them, or try a different bait product if ants don’t appear to be taking it.  It can take 5 to 10 days to see fewer ants.

Read more about Ants. See also Ants Resources.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.


Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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