Ants

Of California’s more than 200 species of ants, only a few are serious pests. The ant most often encountered in our homes and gardens is the non-native Argentine ant. Argentine ant colonies that come in contact with each other communicate and behave as a super colony.

Like other social insects—such as honeybees, termites, and some wasps—individual ants cannot survive alone but must live in colonies. Ants are unique as they can move their entire colony to a more favorable location when necessary. The lifespan of a colony can extend over several years and ants have few natural enemies.

Many ant species are beneficial and should not be indiscriminately destroyed. They feed on organic substances and living insect pests and are one of nature’s most efficient ways of handling insects and smaller animals that die.

Rather than rushing out to get a spray can of poison, consider some of the following suggestions:

  • Store food properly and be vigilant about keeping countertops free of food waste and garbage cans well sealed.
  • Ants will not cross barriers made from sticky materials. Several commercially available materials such as “Tanglefoot” are effective in the home as well as the garden.
  • Fill in cracks by using a good silicon caulk to block the point where ants enter the house.
  • Detergent barriers work better than water barriers because ants can float on water. Mop up ants with a soapy sponge. A dish of pet food can be protected from ants by placing it in a pie pan filled with soapy water.
  • Flooding can drive ants from flowerpots.

Ant problems in plants are almost always an indication of improper horticulture or some imbalance in the system. Something in the garden is not right and the ants are merely taking advantage of the weakness in the plant.

In potted plants, ants are usually a sign that repotting is overdue or that the plant needs different light or fertilizer. Many larger plants don’t grow well in pots so they may need to go into the ground and be replaced with smaller types.

In the landscape, ant problems can be caused by a leaky irrigation (flooding), too much high nitrogen fertilizer (chemical), too little or too much light or soil compaction.

Ants may manipulate other insects like scale, mealy bug, and aphids to harvest the sweet exudates that they produce. Spraying for the pest insect is ineffective; control of the ants will better manage the problem.

Be sure to read all label information before using any of the materials described above.