The Homeowners Column

The Homeowners Column

Controlling Ants – The #1 Urban Pest

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

We're number one! We're number one! There is joy in antville today. Ants are now the number one urban pest, having beat out cockroaches for the honor. However, those aren't foam fingers the ants are carrying but the crumbs from your midnight raid on the cherry pie. What was last night's cast off is now a feast for a family of ants.

Damage from ants varies. Most indoor ants are primarily a nuisance and cause little damage. Carpenter ants can weaken wood in structures. However unlike termites, ants nest in wood but do not eat wood. Generally there are no disease problems associated with ants.

Ants have a wide range of nesting habits and food preferences. Proper identification is important in determining control measures. Some ants build nests in soil producing characteristic mounds while others nest in homes behind moldings, baseboards, countertops and similar places. Still others like carpenter ants nest in decaying or moisture damaged wood.

Ants feed on a variety of foods including starches, meats, fats and sweets. That's why they hang out in the kitchen with us.

Not all ants found outdoors become pests. Ants are important in aerating the soil, controlling pests and even in seed dispersal of many wildflowers. Ant colonies in lawn areas generally do not require control.

A common indoor ant is the odorous house ant. It gets its name from the unpleasant smell it releases when it's crushed. Odorous house ants are brown to dark brown. They are particularly small with the workers about one tenth of an inch long. They like to eat sweets and fatty foods. No wonder they like hanging with us. They nest in soil under stones, boards, patio blocks and nearly any other object laying on the ground. They can nest in homes in wall voids, under floors and even in potted plants. Odorous house ants do not cause structural damage to buildings.

Spraying a pesticide indoors on the occasional worker ant foraging for food is only temporary and has little if any impact on the nest. A quick spray of soapy water can be used to eliminate the wandering foragers. The nest should be found and treated for long-term ant control. Sometimes the nest becomes obvious by following the ants. Ants usually take regular routes to and from their nest and their food by establishing a chemical scent trail. Instead of leaving breadcrumbs to find their way back, they leave a smell to find their way back to the breadcrumbs. First step in ant control is good sanitation, which means no dirty dishes in the sink and wiping counters regularly. Caulk cracks and crevices in house foundation. Keep foods in tightly sealed containers. Glass jars should have rubber gaskets.

Commercial baits can be effective on some ant species. However in order for the baits to work, there must not be any other food sources available. Do not set baits where small children or pets can reach them. A mixture of boric acid and honey or syrup is also an attractive ant bait. When using any pesticide be sure to read and follow all label directions.

To control odorous house ants check for outdoor nests especially under stones, firewood or bricks. Check indoors in the potted plant you rarely water.

If nests are not located, your best bet for long-term control is to call a local professional pest control company. They can use insect growth regulators that only affect insects. The chemicals basically keep the ants from growing up. In addition, professionals are generally more experienced at finding the ant nest.

For more information on identifying ants and their proper control measures, contact U of I Extension at 217-333-7672 for the brochure entitled "What to do about household ants."

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