Ants in Patio Tomato Plants


When you grow plants of any kind, it can be upsetting to find that insects have invaded your garden. While they are common insects both inside and outside the home, ants won't eat or harm your tomatoes and other vegetables. Industrious ants, however, can carry other harmful insects to plants, where they eat the sticky excretion called "honeydew." When you control the ants, you'll likely be eliminating other destructive insects.


Although their presence can be uncomfortable if they bite you or get into your food, ants are hardworking insects that live in colonies with a queen, much like bees. Most species of ants live in soil, but some inhabit wood or hard plant material such as acorns. They do not eat plants, instead dining on dead and living insects, plant nectar and the honeydew that other types of insects excrete. Many kinds of ants have a positive impact on their ecosystems, for example, dispersing seeds and aerating soil, according to the University of Arizona.

Types of Ants

The University of California at Davis website reports that over 12,000 species of ants exist around the world and over 200 of these live in California alone. Of these, however, only about 12 species are considered pests. The Argentine ant is most commonly found in California and a few other states. The pharaoh ant, the odorous house ant, the thief ant and the Southern fire ant are also common. In your outdoor landscape, you might encounter the common velvety tree ant.

Negative Aspects of Ants

When ants interfere with human activities, they are considered pests. Humans often think of the spaces they occupy as belonging to them, without realizing that other creatures share the same environment. Carpenter ants are an example of an insect that can damage the wood of your house when they burrow into it to lay their eggs and raise their larvae. The tropical leafcutter ant competes with humans for certain crops when they cut pieces from plants. And the imported, invasive red fire ant causes painful stings when it comes into contact with human flesh.

Deterring Ants From Your Tomato Plants

If you can catch an ant infestation on your tomato plants when it first begins to occur, you'll have better success in controlling the population before it gets large. Soon after planting your tomato in a pot on your patio, spread out a barrier product such as Tree Tanglefoot around the lower part of the main plant stem. Such products are considered organic and are available at garden supply stores. If you notice a large number of ants on your tomato plant, first spray a sharp stream of water to knock the insects off your plant. Then follow label instructions for applying the barrier product.

Getting Rid of the Ants' "Cows"

Some people refer to the insects that ants bring to plants as their "cows," because they truly farm the creatures for their sweet, sticky excretion known as honeydew. Insects such as aphids, scale and mealybugs can kill your tomato plant if they exist in large numbers for a prolonged period. If you miss catching your ant infestation soon after it begins, the destructive insects will begin to suck the fluid from your tomato plant, turning its leaves yellow and causing them to curl. Begin control efforts by spraying your plant with a sharp stream of water to knock off insects. Then spray your tomato with insecticidal soap, completely covering both sides of the leaves and the entire plant. Repeat daily when the plant is not in full sun until signs of ants and their cows have disappeared.

Keywords: ants tomato plants, garden insect control, aphid scale mealybug

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, GardenGuides and eHow. She earned her B.A. at UCSB and her M.A. from San Jose State University.